- Mar 06, 2019
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Andrey Ryabinin authored
We have common pattern to access lru_lock from a page pointer: zone_lru_lock(page_zone(page)) Which is silly, because it unfolds to this: &NODE_DATA(page_to_nid(page))->node_zones[page_zonenum(page)]->zone_pgdat->lru_lock while we can simply do &NODE_DATA(page_to_nid(page))->lru_lock Remove zone_lru_lock() function, since it's only complicate things. Use 'page_pgdat(page)->lru_lock' pattern instead. [aryabinin@virtuozzo.com: a slightly better version of __split_huge_page()] Link: http://lkml.kernel.org/r/20190301121651.7741-1-aryabinin@virtuozzo.com Link: http://lkml.kernel.org/r/20190228083329.31892-2-aryabinin@virtuozzo.com Signed-off-by:
Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by:
Vlastimil Babka <vbabka@suse.cz> Acked-by:
Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Rik van Riel <riel@surriel.com> Cc: William Kucharski <william.kucharski@oracle.com> Cc: John Hubbard <jhubbard@nvidia.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Mel Gorman authored
Compaction is inherently race-prone as a suitable page freed during compaction can be allocated by any parallel task. This patch uses a capture_control structure to isolate a page immediately when it is freed by a direct compactor in the slow path of the page allocator. The intent is to avoid redundant scanning. 5.0.0-rc1 5.0.0-rc1 selective-v3r17 capture-v3r19 Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%* Amean fault-both-3 2582.11 ( 0.00%) 2563.68 ( 0.71%) Amean fault-both-5 4500.26 ( 0.00%) 4233.52 ( 5.93%) Amean fault-both-7 5819.53 ( 0.00%) 6333.65 ( -8.83%) Amean fault-both-12 9321.18 ( 0.00%) 9759.38 ( -4.70%) Amean fault-both-18 9782.76 ( 0.00%) 10338.76 ( -5.68%) Amean fault-both-24 15272.81 ( 0.00%) 13379.55 * 12.40%* Amean fault-both-30 15121.34 ( 0.00%) 16158.25 ( -6.86%) Amean fault-both-32 18466.67 ( 0.00%) 18971.21 ( -2.73%) Latency is only moderately affected but the devil is in the details. A closer examination indicates that base page fault latency is reduced but latency of huge pages is increased as it takes creater care to succeed. Part of the "problem" is that allocation success rates are close to 100% even when under pressure and compaction gets harder 5.0.0-rc1 5.0.0-rc1 selective-v3r17 capture-v3r19 Percentage huge-3 96.70 ( 0.00%) 98.23 ( 1.58%) Percentage huge-5 96.99 ( 0.00%) 95.30 ( -1.75%) Percentage huge-7 94.19 ( 0.00%) 97.24 ( 3.24%) Percentage huge-12 94.95 ( 0.00%) 97.35 ( 2.53%) Percentage huge-18 96.74 ( 0.00%) 97.30 ( 0.58%) Percentage huge-24 97.07 ( 0.00%) 97.55 ( 0.50%) Percentage huge-30 95.69 ( 0.00%) 98.50 ( 2.95%) Percentage huge-32 96.70 ( 0.00%) 99.27 ( 2.65%) And scan rates are reduced as expected by 6% for the migration scanner and 29% for the free scanner indicating that there is less redundant work. Compaction migrate scanned 20815362 19573286 Compaction free scanned 16352612 11510663 [mgorman@techsingularity.net: remove redundant check] Link: http://lkml.kernel.org/r/20190201143853.GH9565@techsingularity.net Link: http://lkml.kernel.org/r/20190118175136.31341-23-mgorman@techsingularity.net Signed-off-by: -
Mel Gorman authored
Pageblock hints are cleared when compaction restarts or kswapd makes enough progress that it can sleep but it's over-eager in that the bit is cleared for migration sources with no LRU pages and migration targets with no free pages. As pageblock skip hint flushes are relatively rare and out-of-band with respect to kswapd, this patch makes a few more expensive checks to see if it's appropriate to even clear the bit. Every pageblock that is not cleared will avoid 512 pages being scanned unnecessarily on x86-64. The impact is variable with different workloads showing small differences in latency, success rates and scan rates. This is expected as clearing the hints is not that common but doing a small amount of work out-of-band to avoid a large amount of work in-band later is generally a good thing. Link: http://lkml.kernel.org/r/20190118175136.31341-22-mgorman@techsingularity.net Signed-off-by:
Qian Cai <cai@lca.pw> Acked-by:
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Mel Gorman authored
Once fast searching finishes, there is a possibility that the linear scanner is scanning full blocks found by the fast scanner earlier. This patch uses an adaptive stride to sample pageblocks for free pages. The more consecutive full pageblocks encountered, the larger the stride until a pageblock with free pages is found. The scanners might meet slightly sooner but it is an acceptable risk given that the search of the free lists may still encounter the pages and adjust the cached PFN of the free scanner accordingly. 5.0.0-rc1 5.0.0-rc1 roundrobin-v3r17 samplefree-v3r17 Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%* Amean fault-both-3 2752.37 ( 0.00%) 2729.95 ( 0.81%) Amean fault-both-5 4341.69 ( 0.00%) 4397.80 ( -1.29%) Amean fault-both-7 6308.75 ( 0.00%) 6097.61 ( 3.35%) Amean fault-both-12 10241.81 ( 0.00%) 9407.15 ( 8.15%) Amean fault-both-18 13736.09 ( 0.00%) 10857.63 * 20.96%* Amean fault-both-24 16853.95 ( 0.00%) 13323.24 * 20.95%* Amean fault-both-30 15862.61 ( 0.00%) 17345.44 ( -9.35%) Amean fault-both-32 18450.85 ( 0.00%) 16892.00 ( 8.45%) The latency is mildly improved offseting some overhead from earlier patches that are prerequisites for the rest of the series. However, a major impact is on the free scan rate with an 82% reduction. 5.0.0-rc1 5.0.0-rc1 roundrobin-v3r17 samplefree-v3r17 Compaction migrate scanned 21607271 20116887 Compaction free scanned 95336406 16668703 It's also the first time in the series where the number of pages scanned by the migration scanner is greater than the free scanner due to the increased search efficiency. Link: http://lkml.kernel.org/r/20190118175136.31341-21-mgorman@techsingularity.net Signed-off-by: -
Mel Gorman authored
As compaction proceeds and creates high-order blocks, the free list search gets less efficient as the larger blocks are used as compaction targets. Eventually, the larger blocks will be behind the migration scanner for partially migrated pageblocks and the search fails. This patch round-robins what orders are searched so that larger blocks can be ignored and find smaller blocks that can be used as migration targets. The overall impact was small on 1-socket but it avoids corner cases where the migration/free scanners meet prematurely or situations where many of the pageblocks encountered by the free scanner are almost full instead of being properly packed. Previous testing had indicated that without this patch there were occasional large spikes in the free scanner without this patch. [dan.carpenter@oracle.com: fix static checker warning] Link: http://lkml.kernel.org/r/20190118175136.31341-20-mgorman@techsingularity.net Signed-off-by:
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Mel Gorman authored
The fast isolation of free pages allows the cached PFN of the free scanner to advance faster than necessary depending on the contents of the free list. The key is that fast_isolate_freepages() can update zone->compact_cached_free_pfn via isolate_freepages_block(). When the fast search fails, the linear scan can start from a point that has skipped valid migration targets, particularly pageblocks with just low-order free pages. This can cause the migration source/target scanners to meet prematurely causing a reset. This patch starts by avoiding an update of the pageblock skip information and cached PFN from isolate_freepages_block() and puts the responsibility of updating that information in the callers. The fast scanner will update the cached PFN if and only if it finds a block that is higher than the existing cached PFN and sets the skip if the pageblock is full or nearly full. The linear scanner will update skipped information and the cached PFN only when a block is completely scanned. The total impact is that the free scanner advances more slowly as it is primarily driven by the linear scanner instead of the fast search. 5.0.0-rc1 5.0.0-rc1 noresched-v3r17 slowfree-v3r17 Amean fault-both-3 2965.68 ( 0.00%) 3036.75 ( -2.40%) Amean fault-both-5 3995.90 ( 0.00%) 4522.24 * -13.17%* Amean fault-both-7 5842.12 ( 0.00%) 6365.35 ( -8.96%) Amean fault-both-12 9550.87 ( 0.00%) 10340.93 ( -8.27%) Amean fault-both-18 13304.72 ( 0.00%) 14732.46 ( -10.73%) Amean fault-both-24 14618.59 ( 0.00%) 16288.96 ( -11.43%) Amean fault-both-30 16650.96 ( 0.00%) 16346.21 ( 1.83%) Amean fault-both-32 17145.15 ( 0.00%) 19317.49 ( -12.67%) The impact to latency is higher than the last version but it appears to be due to a slight increase in the free scan rates which is a potential side-effect of the patch. However, this is necessary for later patches that are more careful about how pageblocks are treated as earlier iterations of those patches hit corner cases where the restarts were punishing and very visible. Link: http://lkml.kernel.org/r/20190118175136.31341-19-mgorman@techsingularity.net Signed-off-by: -
Mel Gorman authored
Scanning on large machines can take a considerable length of time and eventually need to be rescheduled. This is treated as an abort event but that's not appropriate as the attempt is likely to be retried after making numerous checks and taking another cycle through the page allocator. This patch will check the need to reschedule if necessary but continue the scanning. The main benefit is reduced scanning when compaction is taking a long time or the machine is over-saturated. It also avoids an unnecessary exit of compaction that ends up being retried by the page allocator in the outer loop. 5.0.0-rc1 5.0.0-rc1 synccached-v3r16 noresched-v3r17 Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%* Amean fault-both-3 2958.27 ( 0.00%) 2965.68 ( -0.25%) Amean fault-both-5 4091.90 ( 0.00%) 3995.90 ( 2.35%) Amean fault-both-7 5803.05 ( 0.00%) 5842.12 ( -0.67%) Amean fault-both-12 9481.06 ( 0.00%) 9550.87 ( -0.74%) Amean fault-both-18 14141.51 ( 0.00%) 13304.72 ( 5.92%) Amean fault-both-24 16438.00 ( 0.00%) 14618.59 ( 11.07%) Amean fault-both-30 17531.72 ( 0.00%) 16650.96 ( 5.02%) Amean fault-both-32 17101.96 ( 0.00%) 17145.15 ( -0.25%) Link: http://lkml.kernel.org/r/20190118175136.31341-18-mgorman@techsingularity.net Signed-off-by: -
Mel Gorman authored
With incremental changes, compact_should_abort no longer makes any documented sense. Rename to compact_check_resched and update the associated comments. There is no benefit other than reducing redundant code and making the intent slightly clearer. It could potentially be merged with earlier patches but it just makes the review slightly harder. Link: http://lkml.kernel.org/r/20190118175136.31341-17-mgorman@techsingularity.net Signed-off-by:
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Mel Gorman authored
Migrate has separate cached PFNs for ASYNC and SYNC* migration on the basis that some migrations will fail in ASYNC mode. However, if the cached PFNs match at the start of scanning and pageblocks are skipped due to having no isolation candidates, then the sync state does not matter. This patch keeps matching cached PFNs in sync until a pageblock with isolation candidates is found. The actual benefit is marginal given that the sync scanner following the async scanner will often skip a number of pageblocks but it's useless work. Any benefit depends heavily on whether the scanners restarted recently. Link: http://lkml.kernel.org/r/20190118175136.31341-16-mgorman@techsingularity.net Signed-off-by:
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Mel Gorman authored
When scanning for sources or targets, PageCompound is checked for huge pages as they can be skipped quickly but it happens relatively late after a lot of setup and checking. This patch short-cuts the check to make it earlier. It might still change when the lock is acquired but this has less overhead overall. The free scanner advances but the migration scanner does not. Typically the free scanner encounters more movable blocks that change state over the lifetime of the system and also tends to scan more aggressively as it's actively filling its portion of the physical address space with data. This could change in the future but for the moment, this worked better in practice and incurred fewer scan restarts. The impact on latency and allocation success rates is marginal but the free scan rates are reduced by 15% and system CPU usage is reduced by 3.3%. The 2-socket results are not materially different. Link: http://lkml.kernel.org/r/20190118175136.31341-15-mgorman@techsingularity.net Signed-off-by:
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Mel Gorman authored
Async migration aborts on spinlock contention but contention can be high when there are multiple compaction attempts and kswapd is active. The consequence is that the migration scanners move forward uselessly while still contending on locks for longer while leaving suitable migration sources behind. This patch will acquire the lock but track when contention occurs. When it does, the current pageblock will finish as compaction may succeed for that block and then abort. This will have a variable impact on latency as in some cases useless scanning is avoided (reduces latency) but a lock will be contended (increase latency) or a single contended pageblock is scanned that would otherwise have been skipped (increase latency). 5.0.0-rc1 5.0.0-rc1 norescan-v3r16 finishcontend-v3r16 Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%* Amean fault-both-3 3002.07 ( 0.00%) 3153.17 ( -5.03%) Amean fault-both-5 4684.47 ( 0.00%) 4280.52 ( 8.62%) Amean fault-both-7 6815.54 ( 0.00%) 5811.50 * 14.73%* Amean fault-both-12 10864.02 ( 0.00%) 9276.85 ( 14.61%) Amean fault-both-18 12247.52 ( 0.00%) 11032.67 ( 9.92%) Amean fault-both-24 15683.99 ( 0.00%) 14285.70 ( 8.92%) Amean fault-both-30 18620.02 ( 0.00%) 16293.76 * 12.49%* Amean fault-both-32 19250.28 ( 0.00%) 16721.02 * 13.14%* 5.0.0-rc1 5.0.0-rc1 norescan-v3r16 finishcontend-v3r16 Percentage huge-1 0.00 ( 0.00%) 0.00 ( 0.00%) Percentage huge-3 95.00 ( 0.00%) 96.82 ( 1.92%) Percentage huge-5 94.22 ( 0.00%) 95.40 ( 1.26%) Percentage huge-7 92.35 ( 0.00%) 95.92 ( 3.86%) Percentage huge-12 91.90 ( 0.00%) 96.73 ( 5.25%) Percentage huge-18 89.58 ( 0.00%) 96.77 ( 8.03%) Percentage huge-24 90.03 ( 0.00%) 96.05 ( 6.69%) Percentage huge-30 89.14 ( 0.00%) 96.81 ( 8.60%) Percentage huge-32 90.58 ( 0.00%) 97.41 ( 7.54%) There is a variable impact that is mostly good on latency while allocation success rates are slightly higher. System CPU usage is reduced by about 10% but scan rate impact is mixed Compaction migrate scanned 27997659.00 20148867 Compaction free scanned 120782791.00 118324914 Migration scan rates are reduced 28% which is expected as a pageblock is used by the async scanner instead of skipped. The impact on the free scanner is known to be variable. Overall the primary justification for this patch is that completing scanning of a pageblock is very important for later patches. [yuehaibing@huawei.com: fix unused variable warning] Link: http://lkml.kernel.org/r/20190118175136.31341-14-mgorman@techsingularity.net Signed-off-by: -
Mel Gorman authored
Pageblocks are marked for skip when no pages are isolated after a scan. However, it's possible to hit corner cases where the migration scanner gets stuck near the boundary between the source and target scanner. Due to pages being migrated in blocks of COMPACT_CLUSTER_MAX, pages that are migrated can be reallocated before the pageblock is complete. The pageblock is not necessarily skipped so it can be rescanned multiple times. Similarly, a pageblock with some dirty/writeback pages may fail to migrate and be rescanned until writeback completes which is wasteful. This patch tracks if a pageblock is being rescanned. If so, then the entire pageblock will be migrated as one operation. This narrows the race window during which pages can be reallocated during migration. Secondly, if there are pages that cannot be isolated then the pageblock will still be fully scanned and marked for skipping. On the second rescan, the pageblock skip is set and the migration scanner makes progress. 5.0.0-rc1 5.0.0-rc1 findfree-v3r16 norescan-v3r16 Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%* Amean fault-both-3 3200.68 ( 0.00%) 3002.07 ( 6.21%) Amean fault-both-5 4847.75 ( 0.00%) 4684.47 ( 3.37%) Amean fault-both-7 6658.92 ( 0.00%) 6815.54 ( -2.35%) Amean fault-both-12 11077.62 ( 0.00%) 10864.02 ( 1.93%) Amean fault-both-18 12403.97 ( 0.00%) 12247.52 ( 1.26%) Amean fault-both-24 15607.10 ( 0.00%) 15683.99 ( -0.49%) Amean fault-both-30 18752.27 ( 0.00%) 18620.02 ( 0.71%) Amean fault-both-32 21207.54 ( 0.00%) 19250.28 * 9.23%* 5.0.0-rc1 5.0.0-rc1 findfree-v3r16 norescan-v3r16 Percentage huge-3 96.86 ( 0.00%) 95.00 ( -1.91%) Percentage huge-5 93.72 ( 0.00%) 94.22 ( 0.53%) Percentage huge-7 94.31 ( 0.00%) 92.35 ( -2.08%) Percentage huge-12 92.66 ( 0.00%) 91.90 ( -0.82%) Percentage huge-18 91.51 ( 0.00%) 89.58 ( -2.11%) Percentage huge-24 90.50 ( 0.00%) 90.03 ( -0.52%) Percentage huge-30 91.57 ( 0.00%) 89.14 ( -2.65%) Percentage huge-32 91.00 ( 0.00%) 90.58 ( -0.46%) Negligible difference but this was likely a case when the specific corner case was not hit. A previous run of the same patch based on an earlier iteration of the series showed large differences where migration rates could be halved when the corner case was hit. The specific corner case where migration scan rates go through the roof was due to a dirty/writeback pageblock located at the boundary of the migration/free scanner did not happen in this case. When it does happen, the scan rates multipled by massive margins. Link: http://lkml.kernel.org/r/20190118175136.31341-13-mgorman@techsingularity.net Signed-off-by: -
Mel Gorman authored
Similar to the migration scanner, this patch uses the free lists to quickly locate a migration target. The search is different in that lower orders will be searched for a suitable high PFN if necessary but the search is still bound. This is justified on the grounds that the free scanner typically scans linearly much more than the migration scanner. If a free page is found, it is isolated and compaction continues if enough pages were isolated. For SYNC* scanning, the full pageblock is scanned for any remaining free pages so that is can be marked for skipping in the near future. 1-socket thpfioscale 5.0.0-rc1 5.0.0-rc1 isolmig-v3r15 findfree-v3r16 Amean fault-both-3 3024.41 ( 0.00%) 3200.68 ( -5.83%) Amean fault-both-5 4749.30 ( 0.00%) 4847.75 ( -2.07%) Amean fault-both-7 6454.95 ( 0.00%) 6658.92 ( -3.16%) Amean fault-both-12 10324.83 ( 0.00%) 11077.62 ( -7.29%) Amean fault-both-18 12896.82 ( 0.00%) 12403.97 ( 3.82%) Amean fault-both-24 13470.60 ( 0.00%) 15607.10 * -15.86%* Amean fault-both-30 17143.99 ( 0.00%) 18752.27 ( -9.38%) Amean fault-both-32 17743.91 ( 0.00%) 21207.54 * -19.52%* The impact on latency is variable but the search is optimistic and sensitive to the exact system state. Success rates are similar but the major impact is to the rate of scanning 5.0.0-rc1 5.0.0-rc1 isolmig-v3r15 findfree-v3r16 Compaction migrate scanned 25646769 29507205 Compaction free scanned 201558184 100359571 The free scan rates are reduced by 50%. The 2-socket reductions for the free scanner are more dramatic which is a likely reflection that the machine has more memory. [dan.carpenter@oracle.com: fix static checker warning] [vbabka@suse.cz: correct number of pages scanned for lower orders] Link: http://lkml.kernel.org/r/20190118175136.31341-12-mgorman@techsingularity.net Signed-off-by: -
Mel Gorman authored
Due to either a fast search of the free list or a linear scan, it is possible for multiple compaction instances to pick the same pageblock for migration. This is lucky for one scanner and increased scanning for all the others. It also allows a race between requests on which first allocates the resulting free block. This patch tests and updates the pageblock skip for the migration scanner carefully. When isolating a block, it will check and skip if the block is already in use. Once the zone lock is acquired, it will be rechecked so that only one scanner can set the pageblock skip for exclusive use. Any scanner contending will continue with a linear scan. The skip bit is still set if no pages can be isolated in a range. While this may result in redundant scanning, it avoids unnecessarily acquiring the zone lock when there are no suitable migration sources. 1-socket thpscale Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%* Amean fault-both-3 3390.40 ( 0.00%) 3024.41 ( 10.80%) Amean fault-both-5 5082.28 ( 0.00%) 4749.30 ( 6.55%) Amean fault-both-7 7012.51 ( 0.00%) 6454.95 ( 7.95%) Amean fault-both-12 11346.63 ( 0.00%) 10324.83 ( 9.01%) Amean fault-both-18 15324.19 ( 0.00%) 12896.82 * 15.84%* Amean fault-both-24 16088.50 ( 0.00%) 13470.60 * 16.27%* Amean fault-both-30 18723.42 ( 0.00%) 17143.99 ( 8.44%) Amean fault-both-32 18612.01 ( 0.00%) 17743.91 ( 4.66%) 5.0.0-rc1 5.0.0-rc1 findmig-v3r15 isolmig-v3r15 Percentage huge-3 89.83 ( 0.00%) 92.96 ( 3.48%) Percentage huge-5 91.96 ( 0.00%) 93.26 ( 1.41%) Percentage huge-7 92.85 ( 0.00%) 93.63 ( 0.84%) Percentage huge-12 92.74 ( 0.00%) 92.80 ( 0.07%) Percentage huge-18 91.71 ( 0.00%) 91.62 ( -0.10%) Percentage huge-24 92.13 ( 0.00%) 91.50 ( -0.69%) Percentage huge-30 93.79 ( 0.00%) 92.73 ( -1.13%) Percentage huge-32 91.27 ( 0.00%) 91.94 ( 0.74%) This shows a reasonable reduction in latency as multiple compaction scanners do not operate on the same blocks with a similar allocation success rate. Compaction migrate scanned 41093126 25646769 Migration scan rates are reduced by 38%. Link: http://lkml.kernel.org/r/20190118175136.31341-11-mgorman@techsingularity.net Signed-off-by: -
Mel Gorman authored
The migration scanner is a linear scan of a zone with a potentiall large search space. Furthermore, many pageblocks are unusable such as those filled with reserved pages or partially filled with pages that cannot migrate. These still get scanned in the common case of allocating a THP and the cost accumulates. The patch uses a partial search of the free lists to locate a migration source candidate that is marked as MOVABLE when allocating a THP. It prefers picking a block with a larger number of free pages already on the basis that there are fewer pages to migrate to free the entire block. The lowest PFN found during searches is tracked as the basis of the start for the linear search after the first search of the free list fails. After the search, the free list is shuffled so that the next search will not encounter the same page. If the search fails then the subsequent searches will be shorter and the linear scanner is used. If this search fails, or if the request is for a small or unmovable/reclaimable allocation then the linear scanner is still used. It is somewhat pointless to use the list search in those cases. Small free pages must be used for the search and there is no guarantee that movable pages are located within that block that are contiguous. 5.0.0-rc1 5.0.0-rc1 noboost-v3r10 findmig-v3r15 Amean fault-both-3 3771.41 ( 0.00%) 3390.40 ( 10.10%) Amean fault-both-5 5409.05 ( 0.00%) 5082.28 ( 6.04%) Amean fault-both-7 7040.74 ( 0.00%) 7012.51 ( 0.40%) Amean fault-both-12 11887.35 ( 0.00%) 11346.63 ( 4.55%) Amean fault-both-18 16718.19 ( 0.00%) 15324.19 ( 8.34%) Amean fault-both-24 21157.19 ( 0.00%) 16088.50 * 23.96%* Amean fault-both-30 21175.92 ( 0.00%) 18723.42 * 11.58%* Amean fault-both-32 21339.03 ( 0.00%) 18612.01 * 12.78%* 5.0.0-rc1 5.0.0-rc1 noboost-v3r10 findmig-v3r15 Percentage huge-3 86.50 ( 0.00%) 89.83 ( 3.85%) Percentage huge-5 92.52 ( 0.00%) 91.96 ( -0.61%) Percentage huge-7 92.44 ( 0.00%) 92.85 ( 0.44%) Percentage huge-12 92.98 ( 0.00%) 92.74 ( -0.25%) Percentage huge-18 91.70 ( 0.00%) 91.71 ( 0.02%) Percentage huge-24 91.59 ( 0.00%) 92.13 ( 0.60%) Percentage huge-30 90.14 ( 0.00%) 93.79 ( 4.04%) Percentage huge-32 90.03 ( 0.00%) 91.27 ( 1.37%) This shows an improvement in allocation latencies with similar allocation success rates. While not presented, there was a 31% reduction in migration scanning and a 8% reduction on system CPU usage. A 2-socket machine showed similar benefits. [mgorman@techsingularity.net: several fixes] Link: http://lkml.kernel.org/r/20190204120111.GL9565@techsingularity.net [vbabka@suse.cz: migrate block that was found-fast, some optimisations] Link: http://lkml.kernel.org/r/20190118175136.31341-10-mgorman@techsingularity.net Signed-off-by: -
Mel Gorman authored
When compaction is finishing, it uses a flag to ensure the pageblock is complete but it makes sense to always complete migration of a pageblock. Minimally, skip information is based on a pageblock and partially scanned pageblocks may incur more scanning in the future. The pageblock skip handling also becomes more strict later in the series and the hint is more useful if a complete pageblock was always scanned. The potentially impacts latency as more scanning is done but it's not a consistent win or loss as the scanning is not always a high percentage of the pageblock and sometimes it is offset by future reductions in scanning. Hence, the results are not presented this time due to a misleading mix of gains/losses without any clear pattern. However, full scanning of the pageblock is important for later patches. Link: http://lkml.kernel.org/r/20190118175136.31341-8-mgorman@techsingularity.net Signed-off-by:
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Mel Gorman authored
It's non-obvious that high-order free pages are split into order-0 pages from the function name. Fix it. Link: http://lkml.kernel.org/r/20190118175136.31341-6-mgorman@techsingularity.net Signed-off-by:
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Mel Gorman authored
A zone parameter is passed into a number of top-level compaction functions despite the fact that it's already in compact_control. This is harmless but it did need an audit to check if zone actually ever changes meaningfully. This patches removes the parameter in a number of top-level functions. The change could be much deeper but this was enough to briefly clarify the flow. No functional change. Link: http://lkml.kernel.org/r/20190118175136.31341-5-mgorman@techsingularity.net Signed-off-by:
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Mel Gorman authored
The last_migrated_pfn field is a bit dubious as to whether it really helps but either way, the information from it can be inferred without increasing the size of compact_control so remove the field. Link: http://lkml.kernel.org/r/20190118175136.31341-4-mgorman@techsingularity.net Signed-off-by:
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Matthew Wilcox authored
sysctl_extfrag_handler() neglects to propagate the return value from proc_dointvec_minmax() to its caller. It's a wrapper that doesn't need to exist, so just use proc_dointvec_minmax() directly. Link: http://lkml.kernel.org/r/20190104032557.3056-1-willy@infradead.org Signed-off-by:
Matthew Wilcox <willy@infradead.org> Reported-by:
Aditya Pakki <pakki001@umn.edu> Acked-by:
Randy Dunlap <rdunlap@infradead.org> Signed-off-by:
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- Dec 28, 2018
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Mel Gorman authored
This is a preparation patch only, no functional change. Link: http://lkml.kernel.org/r/20181123114528.28802-3-mgorman@techsingularity.net Signed-off-by:
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- Oct 26, 2018
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Johannes Weiner authored
When systems are overcommitted and resources become contended, it's hard to tell exactly the impact this has on workload productivity, or how close the system is to lockups and OOM kills. In particular, when machines work multiple jobs concurrently, the impact of overcommit in terms of latency and throughput on the individual job can be enormous. In order to maximize hardware utilization without sacrificing individual job health or risk complete machine lockups, this patch implements a way to quantify resource pressure in the system. A kernel built with CONFIG_PSI=y creates files in /proc/pressure/ that expose the percentage of time the system is stalled on CPU, memory, or IO, respectively. Stall states are aggregate versions of the per-task delay accounting delays: cpu: some tasks are runnable but not executing on a CPU memory: tasks are reclaiming, or waiting for swapin or thrashing cache io: tasks are waiting for io completions These percentages of walltime can be thought of as pressure percentages, and they give a general sense of system health and productivity loss incurred by resource overcommit. They can also indicate when the system is approaching lockup scenarios and OOMs. To do this, psi keeps track of the task states associated with each CPU and samples the time they spend in stall states. Every 2 seconds, the samples are averaged across CPUs - weighted by the CPUs' non-idle time to eliminate artifacts from unused CPUs - and translated into percentages of walltime. A running average of those percentages is maintained over 10s, 1m, and 5m periods (similar to the loadaverage). [hannes@cmpxchg.org: doc fixlet, per Randy] Link: http://lkml.kernel.org/r/20180828205625.GA14030@cmpxchg.org [hannes@cmpxchg.org: code optimization] Link: http://lkml.kernel.org/r/20180907175015.GA8479@cmpxchg.org [hannes@cmpxchg.org: rename psi_clock() to psi_update_work(), per Peter] Link: http://lkml.kernel.org/r/20180907145404.GB11088@cmpxchg.org [hannes@cmpxchg.org: fix build] Link: http://lkml.kernel.org/r/20180913014222.GA2370@cmpxchg.org Link: http://lkml.kernel.org/r/20180828172258.3185-9-hannes@cmpxchg.org Signed-off-by:Johannes Weiner <hannes@cmpxchg.org> Acked-by:
Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by:
Daniel Drake <drake@endlessm.com> Tested-by:
Suren Baghdasaryan <surenb@google.com> Cc: Christopher Lameter <cl@linux.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <jweiner@fb.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Enderborg <peter.enderborg@sony.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vinayak Menon <vinmenon@codeaurora.org> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by:
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- Jun 14, 2018
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Joe Perches authored
mm/*.c files use symbolic and octal styles for permissions. Using octal and not symbolic permissions is preferred by many as more readable. https://lkml.org/lkml/2016/8/2/1945 Prefer the direct use of octal for permissions. Done using $ scripts/checkpatch.pl -f --types=SYMBOLIC_PERMS --fix-inplace mm/*.c and some typing. Before: $ git grep -P -w "0[0-7]{3,3}" mm | wc -l 44 After: $ git grep -P -w "0[0-7]{3,3}" mm | wc -l 86 Miscellanea: o Whitespace neatening around these conversions. Link: http://lkml.kernel.org/r/2e032ef111eebcd4c5952bae86763b541d373469.1522102887.git.joe@perches.com Signed-off-by:
Joe Perches <joe@perches.com> Acked-by:
David Rientjes <rientjes@google.com> Acked-by:
Michal Hocko <mhocko@suse.com> Signed-off-by:
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- May 24, 2018
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Joonsoo Kim authored
This reverts the following commits that change CMA design in MM. 3d2054ad ("ARM: CMA: avoid double mapping to the CMA area if CONFIG_HIGHMEM=y") 1d47a3ec ("mm/cma: remove ALLOC_CMA") bad8c6c0 ("mm/cma: manage the memory of the CMA area by using the ZONE_MOVABLE") Ville reported a following error on i386. Inode-cache hash table entries: 65536 (order: 6, 262144 bytes) microcode: microcode updated early to revision 0x4, date = 2013-06-28 Initializing CPU#0 Initializing HighMem for node 0 (000377fe:00118000) Initializing Movable for node 0 (00000001:00118000) BUG: Bad page state in process swapper pfn:377fe page:f53effc0 count:0 mapcount:-127 mapping:00000000 index:0x0 flags: 0x80000000() raw: 80000000 00000000 00000000 ffffff80 00000000 00000100 00000200 00000001 page dumped because: nonzero mapcount Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 4.17.0-rc5-elk+ #145 Hardware name: Dell Inc. Latitude E5410/03VXMC, BIOS A15 07/11/2013 Call Trace: dump_stack+0x60/0x96 bad_page+0x9a/0x100 free_pages_check_bad+0x3f/0x60 free_pcppages_bulk+0x29d/0x5b0 free_unref_page_commit+0x84/0xb0 free_unref_page+0x3e/0x70 __free_pages+0x1d/0x20 free_highmem_page+0x19/0x40 add_highpages_with_active_regions+0xab/0xeb set_highmem_pages_init+0x66/0x73 mem_init+0x1b/0x1d7 start_kernel+0x17a/0x363 i386_start_kernel+0x95/0x99 startup_32_smp+0x164/0x168 The reason for this error is that the span of MOVABLE_ZONE is extended to whole node span for future CMA initialization, and, normal memory is wrongly freed here. I submitted the fix and it seems to work, but, another problem happened. It's so late time to fix the later problem so I decide to reverting the series. Reported-by:
Ville Syrjälä <ville.syrjala@linux.intel.com> Acked-by:
Laura Abbott <labbott@redhat.com> Acked-by:
Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by:
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- Apr 11, 2018
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Joonsoo Kim authored
Now, all reserved pages for CMA region are belong to the ZONE_MOVABLE and it only serves for a request with GFP_HIGHMEM && GFP_MOVABLE. Therefore, we don't need to maintain ALLOC_CMA at all. Link: http://lkml.kernel.org/r/1512114786-5085-3-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by:
Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Tested-by:
Tony Lindgren <tony@atomide.com> Acked-by:
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Michal Hocko authored
No allocation callback is using this argument anymore. new_page_node used to use this parameter to convey node_id resp. migration error up to move_pages code (do_move_page_to_node_array). The error status never made it into the final status field and we have a better way to communicate node id to the status field now. All other allocation callbacks simply ignored the argument so we can drop it finally. [mhocko@suse.com: fix migration callback] Link: http://lkml.kernel.org/r/20180105085259.GH2801@dhcp22.suse.cz [akpm@linux-foundation.org: fix alloc_misplaced_dst_page()] [mhocko@kernel.org: fix build] Link: http://lkml.kernel.org/r/20180103091134.GB11319@dhcp22.suse.cz Link: http://lkml.kernel.org/r/20180103082555.14592-3-mhocko@kernel.org Signed-off-by:
Zi Yan <zi.yan@cs.rutgers.edu> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by:
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- Apr 06, 2018
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Mike Rapoport authored
Link: http://lkml.kernel.org/r/1519585191-10180-4-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by:
Mike Rapoport <rppt@linux.vnet.ibm.com> Reviewed-by:
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David Rientjes authored
It's possible for free pages to become stranded on per-cpu pagesets (pcps) that, if drained, could be merged with buddy pages on the zone's free area to form large order pages, including up to MAX_ORDER. Consider a verbose example using the tools/vm/page-types tool at the beginning of a ZONE_NORMAL ('B' indicates a buddy page and 'S' indicates a slab page). Pages on pcps do not have any page flags set. 109954 1 _______S________________________________________________________ 109955 2 __________B_____________________________________________________ 109957 1 ________________________________________________________________ 109958 1 __________B_____________________________________________________ 109959 7 ________________________________________________________________ 109960 1 __________B_____________________________________________________ 109961 9 ________________________________________________________________ 10996a 1 __________B_____________________________________________________ 10996b 3 ________________________________________________________________ 10996e 1 __________B_____________________________________________________ 10996f 1 ________________________________________________________________ ... 109f8c 1 __________B_____________________________________________________ 109f8d 2 ________________________________________________________________ 109f8f 2 __________B_____________________________________________________ 109f91 f ________________________________________________________________ 109fa0 1 __________B_____________________________________________________ 109fa1 7 ________________________________________________________________ 109fa8 1 __________B_____________________________________________________ 109fa9 1 ________________________________________________________________ 109faa 1 __________B_____________________________________________________ 109fab 1 _______S________________________________________________________ The compaction migration scanner is attempting to defragment this memory since it is at the beginning of the zone. It has done so quite well, all movable pages have been migrated. From pfn [0x109955, 0x109fab), there are only buddy pages and pages without flags set. These pages may be stranded on pcps that could otherwise allow this memory to be coalesced if freed back to the zone free area. It is possible that some of these pages may not be on pcps and that something has called alloc_pages() and used the memory directly, but we rely on the absence of __GFP_MOVABLE in these cases to allocate from MIGATE_UNMOVABLE pageblocks to try to keep these MIGRATE_MOVABLE pageblocks as free as possible. These buddy and pcp pages, spanning 1,621 pages, could be coalesced and allow for three transparent hugepages to be dynamically allocated. Running the numbers for all such spans on the system, it was found that there were over 400 such spans of only buddy pages and pages without flags set at the time this /proc/kpageflags sample was collected. Without this support, there were _no_ order-9 or order-10 pages free. When kcompactd fails to defragment memory such that a cc.order page can be allocated, drain all pcps for the zone back to the buddy allocator so this stranding cannot occur. Compaction for that order will subsequently be deferred, which acts as a ratelimit on this drain. Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1803010340100.88270@chino.kir.corp.google.com Signed-off-by:
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- Feb 01, 2018
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Yang Shi authored
"mode" argument is not used by try_to_compact_pages() and sub functions anymore, it has been replaced by "prio". Fix the comment to explain the use of "prio" argument. Link: http://lkml.kernel.org/r/1515801336-20611-1-git-send-email-yang.shi@linux.alibaba.com Signed-off-by:
Yang Shi <yang.shi@linux.alibaba.com> Acked-by:
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- Nov 18, 2017
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Vlastimil Babka authored
Commit f3c931633a59 ("mm, compaction: persistently skip hugetlbfs pageblocks") has introduced pageblock_skip_persistent() checks into migration and free scanners, to make sure pageblocks that should be persistently skipped are marked as such, regardless of the ignore_skip_hint flag. Since the previous patch introduced a new no_set_skip_hint flag, the ignore flag no longer prevents marking pageblocks as skipped. Therefore we can remove the special cases. The relevant pageblocks will be marked as skipped by the common logic which marks each pageblock where no page could be isolated. This makes the code simpler. Link: http://lkml.kernel.org/r/20171102121706.21504-3-vbabka@suse.cz Signed-off-by: -
Vlastimil Babka authored
Pageblock skip hints were added as a heuristic for compaction, which shares core code with CMA. Since CMA reliability would suffer from the heuristics, compact_control flag ignore_skip_hint was added for the CMA use case. Since 6815bf3f ("mm/compaction: respect ignore_skip_hint in update_pageblock_skip") the flag also means that CMA won't *update* the skip hints in addition to ignoring them. Today, direct compaction can also ignore the skip hints in the last resort attempt, but there's no reason not to set them when isolation fails in such case. Thus, this patch splits off a new no_set_skip_hint flag to avoid the updating, which only CMA sets. This should improve the heuristics a bit, and allow us to simplify the persistent skip bit handling as the next step. Link: http://lkml.kernel.org/r/20171102121706.21504-2-vbabka@suse.cz Signed-off-by:
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Vlastimil Babka authored
pageblock_skip_persistent() checks for HugeTLB pages of pageblock order. When clearing pageblock skip bits for compaction, the bits are not cleared for such pageblocks, because they cannot contain base pages suitable for migration, nor free pages to use as migration targets. This optimization can be simply extended to all compound pages of order equal or larger than pageblock order, because migrating such pages (if they support it) cannot help sub-pageblock fragmentation. This includes THP's and also gigantic HugeTLB pages, which the current implementation doesn't persistently skip due to a strict pageblock_order equality check and not recognizing tail pages. While THP pages are generally less "persistent" than HugeTLB, we can still expect that if a THP exists at the point of __reset_isolation_suitable(), it will exist also during the subsequent compaction run. The time difference here could be actually smaller than between a compaction run that sets a (non-persistent) skip bit on a THP, and the next compaction run that observes it. Link: http://lkml.kernel.org/r/20171102121706.21504-1-vbabka@suse.cz Signed-off-by:
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David Rientjes authored
It is pointless to migrate hugetlb memory as part of memory compaction if the hugetlb size is equal to the pageblock order. No defragmentation is occurring in this condition. It is also pointless to for the freeing scanner to scan a pageblock where a hugetlb page is pinned. Unconditionally skip these pageblocks, and do so peristently so that they are not rescanned until it is observed that these hugepages are no longer pinned. It would also be possible to do this by involving the hugetlb subsystem in marking pageblocks to no longer be skipped when they hugetlb pages are freed. This is a simple solution that doesn't involve any additional subsystems in pageblock skip manipulation. [rientjes@google.com: fix build] Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1708201734390.117182@chino.kir.corp.google.com Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1708151639130.106658@chino.kir.corp.google.com Signed-off-by:
Michal Hocko <mhocko@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by:
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David Rientjes authored
Kcompactd is needlessly ignoring pageblock skip information. It is doing MIGRATE_SYNC_LIGHT compaction, which is no more powerful than MIGRATE_SYNC compaction. If compaction recently failed to isolate memory from a set of pageblocks, there is nothing to indicate that kcompactd will be able to do so, or that it is beneficial from attempting to isolate memory. Use the pageblock skip hint to avoid rescanning pageblocks needlessly until that information is reset. Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1708151638550.106658@chino.kir.corp.google.com Signed-off-by:
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- Nov 02, 2017
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Greg Kroah-Hartman authored
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by:
Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by:
Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by:
Thomas Gleixner <tglx@linutronix.de> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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- Oct 04, 2017
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Davidlohr Bueso authored
Andrea brought to my attention that the L->{L,S} guarantees are completely bogus for this case. I was looking at the diagram, from the offending commit, when that _is_ the race, we had the load reordered already. What we need is at least S->L semantics, thus simply use wq_has_sleeper() to serialize the call for good. Link: http://lkml.kernel.org/r/20170914175313.GB811@linux-80c1.suse Fixes: 46acef04 (mm,compaction: serialize waitqueue_active() checks) Signed-off-by:Davidlohr Bueso <dbueso@suse.de> Reported-by:
Andrea Parri <parri.andrea@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by:
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- Jul 06, 2017
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Michal Hocko authored
__reset_isolation_suitable walks the whole zone pfn range and it tries to jump over holes by checking the zone for each page. It might still stumble over offline pages, though. Skip those by checking pfn_to_online_page() Link: http://lkml.kernel.org/r/20170515085827.16474-9-mhocko@kernel.org Signed-off-by:
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- May 09, 2017
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Vlastimil Babka authored
The main goal of direct compaction is to form a high-order page for allocation, but it should also help against long-term fragmentation when possible. Most lower-than-pageblock-order compactions are for non-movable allocations, which means that if we compact in a movable pageblock and terminate as soon as we create the high-order page, it's unlikely that the fallback heuristics will claim the whole block. Instead there might be a single unmovable page in a pageblock full of movable pages, and the next unmovable allocation might pick another pageblock and increase long-term fragmentation. To help against such scenarios, this patch changes the termination criteria for compaction so that the current pageblock is finished even though the high-order page already exists. Note that it might be possible that the high-order page formed elsewhere in the zone due to parallel activity, but this patch doesn't try to detect that. This is only done with sync compaction, because async compaction is limited to pageblock of the same migratetype, where it cannot result in a migratetype fallback. (Async compaction also eagerly skips order-aligned blocks where isolation fails, which is against the goal of migrating away as much of the pageblock as possible.) As a result of this patch, long-term memory fragmentation should be reduced. In testing based on 4.9 kernel with stress-highalloc from mmtests configured for order-4 GFP_KERNEL allocations, this patch has reduced the number of unmovable allocations falling back to movable pageblocks by 20%. The number Link: http://lkml.kernel.org/r/20170307131545.28577-9-vbabka@suse.cz Signed-off-by:
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Vlastimil Babka authored
The migrate scanner in async compaction is currently limited to MIGRATE_MOVABLE pageblocks. This is a heuristic intended to reduce latency, based on the assumption that non-MOVABLE pageblocks are unlikely to contain movable pages. However, with the exception of THP's, most high-order allocations are not movable. Should the async compaction succeed, this increases the chance that the non-MOVABLE allocations will fallback to a MOVABLE pageblock, making the long-term fragmentation worse. This patch attempts to help the situation by changing async direct compaction so that the migrate scanner only scans the pageblocks of the requested migratetype. If it's a non-MOVABLE type and there are such pageblocks that do contain movable pages, chances are that the allocation can succeed within one of such pageblocks, removing the need for a fallback. If that fails, the subsequent sync attempt will ignore this restriction. In testing based on 4.9 kernel with stress-highalloc from mmtests configured for order-4 GFP_KERNEL allocations, this patch has reduced the number of unmovable allocations falling back to movable pageblocks by 30%. The number of movable allocations falling back is reduced by 12%. Link: http://lkml.kernel.org/r/20170307131545.28577-8-vbabka@suse.cz Signed-off-by:
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Vlastimil Babka authored
Preparation patch. We are going to need migratetype at lower layers than compact_zone() and compact_finished(). Link: http://lkml.kernel.org/r/20170307131545.28577-7-vbabka@suse.cz Signed-off-by:
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