- Jun 30, 2006
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Christoph Lameter authored
Conversion of nr_writeback to per zone counter. This removes the last page_state counter from arch/i386/mm/pgtable.c so we drop the page_state from there. [akpm@osdl.org: bugfix] Signed-off-by:
Christoph Lameter <clameter@sgi.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by:
Andrew Morton <akpm@osdl.org> Signed-off-by:
Linus Torvalds <torvalds@osdl.org>
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Christoph Lameter authored
This makes nr_dirty a per zone counter. Looping over all processors is avoided during writeback state determination. The counter aggregation for nr_dirty had to be undone in the NFS layer since we summed up the page counts from multiple zones. Someone more familiar with NFS should probably review what I have done. [akpm@osdl.org: bugfix] Signed-off-by:
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Christoph Lameter authored
Conversion of nr_page_table_pages to a per zone counter [akpm@osdl.org: bugfix] Signed-off-by:
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Christoph Lameter authored
- Allows reclaim to access counter without looping over processor counts. - Allows accurate statistics on how many pages are used in a zone by the slab. This may become useful to balance slab allocations over various zones. [akpm@osdl.org: bugfix] Signed-off-by:
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Christoph Lameter authored
Currently a single atomic variable is used to establish the size of the page cache in the whole machine. The zoned VM counters have the same method of implementation as the nr_pagecache code but also allow the determination of the pagecache size per zone. Remove the special implementation for nr_pagecache and make it a zoned counter named NR_FILE_PAGES. Updates of the page cache counters are always performed with interrupts off. We can therefore use the __ variant here. Signed-off-by:
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Christoph Lameter authored
nr_mapped is important because it allows a determination of how many pages of a zone are not mapped, which would allow a more efficient means of determining when we need to reclaim memory in a zone. We take the nr_mapped field out of the page state structure and define a new per zone counter named NR_FILE_MAPPED (the anonymous pages will be split off from NR_MAPPED in the next patch). We replace the use of nr_mapped in various kernel locations. This avoids the looping over all processors in try_to_free_pages(), writeback, reclaim (swap + zone reclaim). [akpm@osdl.org: bugfix] Signed-off-by:
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Christoph Lameter authored
Per zone counter infrastructure The counters that we currently have for the VM are split per processor. The processor however has not much to do with the zone these pages belong to. We cannot tell f.e. how many ZONE_DMA pages are dirty. So we are blind to potentially inbalances in the usage of memory in various zones. F.e. in a NUMA system we cannot tell how many pages are dirty on a particular node. If we knew then we could put measures into the VM to balance the use of memory between different zones and different nodes in a NUMA system. For example it would be possible to limit the dirty pages per node so that fast local memory is kept available even if a process is dirtying huge amounts of pages. Another example is zone reclaim. We do not know how many unmapped pages exist per zone. So we just have to try to reclaim. If it is not working then we pause and try again later. It would be better if we knew when it makes sense to reclaim unmapped pages from a zone. This patchset allows the determination of the number of unmapped pages per zone. We can remove the zone reclaim interval with the counters introduced here. Futhermore the ability to have various usage statistics available will allow the development of new NUMA balancing algorithms that may be able to improve the decision making in the scheduler of when to move a process to another node and hopefully will also enable automatic page migration through a user space program that can analyse the memory load distribution and then rebalance memory use in order to increase performance. The counter framework here implements differential counters for each processor in struct zone. The differential counters are consolidated when a threshold is exceeded (like done in the current implementation for nr_pageache), when slab reaping occurs or when a consolidation function is called. Consolidation uses atomic operations and accumulates counters per zone in the zone structure and also globally in the vm_stat array. VM functions can access the counts by simply indexing a global or zone specific array. The arrangement of counters in an array also simplifies processing when output has to be generated for /proc/*. Counters can be updated by calling inc/dec_zone_page_state or _inc/dec_zone_page_state analogous to *_page_state. The second group of functions can be called if it is known that interrupts are disabled. Special optimized increment and decrement functions are provided. These can avoid certain checks and use increment or decrement instructions that an architecture may provide. We also add a new CONFIG_DMA_IS_NORMAL that signifies that an architecture can do DMA to all memory and therefore ZONE_NORMAL will not be populated. This is only currently set for IA64 SGI SN2 and currently only affects node_page_state(). In the best case node_page_state can be reduced to retrieving a single counter for the one zone on the node. [akpm@osdl.org: cleanups] [akpm@osdl.org: export vm_stat[] for filesystems] Signed-off-by:
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Christoph Lameter authored
NOTE: ZVC are *not* the lightweight event counters. ZVCs are reliable whereas event counters do not need to be. Zone based VM statistics are necessary to be able to determine what the state of memory in one zone is. In a NUMA system this can be helpful for local reclaim and other memory optimizations that may be able to shift VM load in order to get more balanced memory use. It is also useful to know how the computing load affects the memory allocations on various zones. This patchset allows the retrieval of that data from userspace. The patchset introduces a framework for counters that is a cross between the existing page_stats --which are simply global counters split per cpu-- and the approach of deferred incremental updates implemented for nr_pagecache. Small per cpu 8 bit counters are added to struct zone. If the counter exceeds certain thresholds then the counters are accumulated in an array of atomic_long in the zone and in a global array that sums up all zone values. The small 8 bit counters are next to the per cpu page pointers and so they will be in high in the cpu cache when pages are allocated and freed. Access to VM counter information for a zone and for the whole machine is then possible by simply indexing an array (Thanks to Nick Piggin for pointing out that approach). The access to the total number of pages of various types does no longer require the summing up of all per cpu counters. Benefits of this patchset right now: - Ability for UP and SMP configuration to determine how memory is balanced between the DMA, NORMAL and HIGHMEM zones. - loops over all processors are avoided in writeback and reclaim paths. We can avoid caching the writeback information because the needed information is directly accessible. - Special handling for nr_pagecache removed. - zone_reclaim_interval vanishes since VM stats can now determine when it is worth to do local reclaim. - Fast inline per node page state determination. - Accurate counters in /sys/devices/system/node/node*/meminfo. Current counters are counting simply which processor allocated a page somewhere and guestimate based on that. So the counters were not useful to show the actual distribution of page use on a specific zone. - The swap_prefetch patch requires per node statistics in order to figure out when processors of a node can prefetch. This patch provides some of the needed numbers. - Detailed VM counters available in more /proc and /sys status files. References to earlier discussions: V1 http://marc.theaimsgroup.com/?l=linux-kernel&m=113511649910826&w=2 V2 http://marc.theaimsgroup.com/?l=linux-kernel&m=114980851924230&w=2 V3 http://marc.theaimsgroup.com/?l=linux-kernel&m=115014697910351&w=2 V4 http://marc.theaimsgroup.com/?l=linux-kernel&m=115024767318740&w=2 Performance tests with AIM7 did not show any regressions. Seems to be a tad faster even. Tested on ia64/NUMA. Builds fine on i386, SMP / UP. Includes fixes for s390/arm/uml arch code. This patch: Move counter code from page_alloc.c/page-flags.h to vmstat.c/h. Create vmstat.c/vmstat.h by separating the counter code and the proc functions. Move the vm_stat_text array before zoneinfo_show. [akpm@osdl.org: s390 build fix] [akpm@osdl.org: HOTPLUG_CPU build fix] Signed-off-by:
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- Jun 28, 2006
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Ingo Molnar authored
Add debug_check_no_locks_freed(), as a central inline to add bad-lock-free-debugging functionality to. Signed-off-by:
Ingo Molnar <mingo@elte.hu> Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Signed-off-by:
Arjan van de Ven <arjan@linux.intel.com> Signed-off-by:
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Chandra Seetharaman authored
Make notifier_blocks associated with cpu_notifier as __cpuinitdata. __cpuinitdata makes sure that the data is init time only unless CONFIG_HOTPLUG_CPU is defined. Signed-off-by:
Chandra Seetharaman <sekharan@us.ibm.com> Cc: Ashok Raj <ashok.raj@intel.com> Signed-off-by:
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Chandra Seetharaman authored
In 2.6.17, there was a problem with cpu_notifiers and XFS. I provided a band-aid solution to solve that problem. In the process, i undid all the changes you both were making to ensure that these notifiers were available only at init time (unless CONFIG_HOTPLUG_CPU is defined). We deferred the real fix to 2.6.18. Here is a set of patches that fixes the XFS problem cleanly and makes the cpu notifiers available only at init time (unless CONFIG_HOTPLUG_CPU is defined). If CONFIG_HOTPLUG_CPU is defined then cpu notifiers are available at run time. This patch reverts the notifier_call changes made in 2.6.17 Signed-off-by:
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- Jun 26, 2006
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Andreas Mohr authored
acquired (aquired) contiguous (contigious) successful (succesful, succesfull) surprise (suprise) whether (weather) some other misspellings Signed-off-by:
Andreas Mohr <andi@lisas.de> Signed-off-by:
Adrian Bunk <bunk@stusta.de>
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- Jun 25, 2006
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Chris Wright authored
This is redundant with check in wakeup_kswapd. Signed-off-by:
Chris Wright <chrisw@sous-sol.org> Acked-by:
Paul Jackson <pj@sgi.com> Acked-by:
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- Jun 23, 2006
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Kirill Korotaev authored
This patch fixes printk() under zone->lock in show_free_areas(). It can be unsafe to call printk() under this lock, since caller can try to allocate/free some memory and selfdeadlock on this lock. I found allocations/freeing mem both in netconsole and serial console. This issue was faced in reallity when meminfo was periodically printed for debug purposes and netconsole was used. Signed-off-by:
Kirill Korotaev <dev@openvz.org> Signed-off-by:
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Andrew Morton authored
Initialise total_memory earlier in boot. Because if for some reason we run page reclaim early in boot, we don't want total_memory to be zero when we use it as a divisor. And rename total_memory to vm_total_pages to avoid naming clashes with architectures. Cc: Yasunori Goto <y-goto@jp.fujitsu.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Martin Bligh <mbligh@google.com> Signed-off-by:
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Andy Whitcroft authored
We have architectures where the size of page_to_pfn and pfn_to_page are significant enough to overall image size that they wish to push them out of line. However, in the process we have grown a second copy of the implementation of each of these routines for each memory model. Share the implmentation exposing it either inline or out-of-line as required. Signed-off-by:
Andy Whitcroft <apw@shadowen.org> Signed-off-by:
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Yasunori Goto authored
In current code, zonelist is considered to be build once, no modification. But MemoryHotplug can add new zone/pgdat. It must be updated. This patch modifies build_all_zonelists(). By this, build_all_zonelist() can reconfig pgdat's zonelists. To update them safety, this patch use stop_machine_run(). Other cpus don't touch among updating them by using it. In old version (V2 of node hotadd), kernel updated them after zone initialization. But present_page of its new zone is still 0, because online_page() is not called yet at this time. Build_zonelists() checks present_pages to find present zone. It was too early. So, I changed it after online_pages(). Signed-off-by:
Yasunori Goto <y-goto@jp.fujitsu.com> Signed-off-by:
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by:
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Yasunori Goto authored
Wait_table is initialized according to zone size at boot time. But, we cannot know the maixmum zone size when memory hotplug is enabled. It can be changed.... And resizing of wait_table is hard. So kernel allocate and initialzie wait_table as its maximum size. Signed-off-by:
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Yasunori Goto authored
[PATCH] wait_table and zonelist initializing for memory hotadd: add return code for init_current_empty_zone When add_zone() is called against empty zone (not populated zone), we have to initialize the zone which didn't initialize at boot time. But, init_currently_empty_zone() may fail due to allocation of wait table. So, this patch is to catch its error code. Changes against wait_table is in the next patch. Signed-off-by:
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Yasunori Goto authored
[PATCH] wait_table and zonelist initializing for memory hotadd: change to meminit for build_zonelist Change definitions of some functions and data from __init to __meminit. These functions and data can be used after bootup by this patch to be used for hot-add codes. Signed-off-by:
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Yasunori Goto authored
This is just to rename from wait_table_size() to wait_table_hash_nr_entries(). Signed-off-by:
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Andy Whitcroft authored
The buddy allocator has a requirement that boundaries between contigious zones occur aligned with the the MAX_ORDER ranges. Where they do not we will incorrectly merge pages cross zone boundaries. This can lead to pages from the wrong zone being handed out. Originally the buddy allocator would check that buddies were in the same zone by referencing the zone start and end page frame numbers. This was removed as it became very expensive and the buddy allocator already made the assumption that zones boundaries were aligned. It is clear that not all configurations and architectures are honouring this alignment requirement. Therefore it seems safest to reintroduce support for non-aligned zone boundaries. This patch introduces a new check when considering a page a buddy it compares the zone_table index for the two pages and refuses to merge the pages where they do not match. The zone_table index is unique for each node/zone combination when FLATMEM/DISCONTIGMEM is enabled and for each section/zone combination when SPARSEMEM is enabled (a SPARSEMEM section is at least a MAX_ORDER size). Signed-off-by:
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- May 21, 2006
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Bob Picco authored
Andy added code to buddy allocator which does not require the zone's endpoints to be aligned to MAX_ORDER. An issue is that the buddy allocator requires the node_mem_map's endpoints to be MAX_ORDER aligned. Otherwise __page_find_buddy could compute a buddy not in node_mem_map for partial MAX_ORDER regions at zone's endpoints. page_is_buddy will detect that these pages at endpoints are not PG_buddy (they were zeroed out by bootmem allocator and not part of zone). Of course the negative here is we could waste a little memory but the positive is eliminating all the old checks for zone boundary conditions. SPARSEMEM won't encounter this issue because of MAX_ORDER size constraint when SPARSEMEM is configured. ia64 VIRTUAL_MEM_MAP doesn't need the logic either because the holes and endpoints are handled differently. This leaves checking alloc_remap and other arches which privately allocate for node_mem_map. Signed-off-by:
Bob Picco <bob.picco@hp.com> Acked-by:
Mel Gorman <mel@csn.ul.ie> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by:
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Paul Jackson authored
Fix a couple of infrequently encountered 'sleeping function called from invalid context' in the cpuset hooks in __alloc_pages. Could sleep while interrupts disabled. The routine cpuset_zone_allowed() is called by code in mm/page_alloc.c __alloc_pages() to determine if a zone is allowed in the current tasks cpuset. This routine can sleep, for certain GFP_KERNEL allocations, if the zone is on a memory node not allowed in the current cpuset, but might be allowed in a parent cpuset. But we can't sleep in __alloc_pages() if in interrupt, nor if called for a GFP_ATOMIC request (__GFP_WAIT not set in gfp_flags). The rule was intended to be: Don't call cpuset_zone_allowed() if you can't sleep, unless you pass in the __GFP_HARDWALL flag set in gfp_flag, which disables the code that might scan up ancestor cpusets and sleep. This rule was being violated in a couple of places, due to a bogus change made (by myself, pj) to __alloc_pages() as part of the November 2005 effort to cleanup its logic, and also due to a later fix to constrain which swap daemons were awoken. The bogus change can be seen at: http://linux.derkeiler.com/Mailing-Lists/Kernel/2005-11/4691.html [PATCH 01/05] mm fix __alloc_pages cpuset ALLOC_* flags This was first noticed on a tight memory system, in code that was disabling interrupts and doing allocation requests with __GFP_WAIT not set, which resulted in __might_sleep() writing complaints to the log "Debug: sleeping function called ...", when the code in cpuset_zone_allowed() tried to take the callback_sem cpuset semaphore. We haven't seen a system hang on this 'might_sleep' yet, but we are at decent risk of seeing it fairly soon, especially since the additional cpuset_zone_allowed() check was added, conditioning wakeup_kswapd(), in March 2006. Special thanks to Dave Chinner, for figuring this out, and a tip of the hat to Nick Piggin who warned me of this back in Nov 2005, before I was ready to listen. Signed-off-by:
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- May 15, 2006
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Andrew Morton authored
As pointed out in http://bugzilla.kernel.org/show_bug.cgi?id=6490 , this function can experience overflows on 32-bit machines, causing our response to changed values of min_free_kbytes to go whacky. Fixing it efficiently is all too hard, so fix it with 64-bit math instead. Cc: Ake Sandgren <ake.sandgren@hpc2n.umu.se> Cc: Martin Bligh <mbligh@google.com> Signed-off-by:
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- Apr 26, 2006
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Chandra Seetharaman authored
Few of the notifier_chain_register() callers use __init in the definition of notifier_call. It is incorrect as the function definition should be available after the initializations (they do not unregister them during initializations). This patch fixes all such usages to _not_ have the notifier_call __init section. Signed-off-by:
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- Apr 19, 2006
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Andrew Morton authored
Fix up some whitespace damage. Signed-off-by:
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- Apr 11, 2006
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Hideo AOKI authored
These patches are an enhancement of OVERCOMMIT_GUESS algorithm in __vm_enough_memory(). - why the kernel needed patching When the kernel can't allocate anonymous pages in practice, currnet OVERCOMMIT_GUESS could return success. This implementation might be the cause of oom kill in memory pressure situation. If the Linux runs with page reservation features like /proc/sys/vm/lowmem_reserve_ratio and without swap region, I think the oom kill occurs easily. - the overall design approach in the patch When the OVERCOMMET_GUESS algorithm calculates number of free pages, the reserved free pages are regarded as non-free pages. This change helps to avoid the pitfall that the number of free pages become less than the number which the kernel tries to keep free. - testing results I tested the patches using my test kernel module. If the patches aren't applied to the kernel, __vm_enough_memory() returns success in the situation but autual page allocation is failed. On the other hand, if the patches are applied to the kernel, memory allocation failure is avoided since __vm_enough_memory() returns failure in the situation. I checked that on i386 SMP 16GB memory machine. I haven't tested on nommu environment currently. This patch adds totalreserve_pages for __vm_enough_memory(). Calculate_totalreserve_pages() checks maximum lowmem_reserve pages and pages_high in each zone. Finally, the function stores the sum of each zone to totalreserve_pages. The totalreserve_pages is calculated when the VM is initilized. And the variable is updated when /proc/sys/vm/lowmem_reserve_raito or /proc/sys/vm/min_free_kbytes are changed. Signed-off-by:
Hideo Aoki <haoki@redhat.com> Signed-off-by:
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- Apr 10, 2006
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Nick Piggin authored
Rohit found an obscure bug causing buddy list corruption. page_is_buddy is using a non-atomic test (PagePrivate && page_count == 0) to determine whether or not a free page's buddy is itself free and in the buddy lists. Each of the conjuncts may be true at different times due to unrelated conditions, so the non-atomic page_is_buddy test may find each conjunct to be true even if they were not both true at the same time (ie. the page was not on the buddy lists). Signed-off-by:
Martin Bligh <mbligh@google.com> Signed-off-by:
Rohit Seth <rohitseth@google.com> Signed-off-by:
Nick Piggin <npiggin@suse.de> Signed-off-by:
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- Mar 27, 2006
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KAMEZAWA Hiroyuki authored
By using for_each_online_pgdat(), pgdat_list is not necessary now. This patch removes it. Signed-off-by:
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KAMEZAWA Hiroyuki authored
Replace for_each_pgdat() with for_each_online_pgdat(). Signed-off-by:
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KAMEZAWA Hiroyuki authored
This patch removes zone_mem_map. pfn_to_page uses pgdat, page_to_pfn uses zone. page_to_pfn can use pgdat instead of zone, which is only one user of zone_mem_map. By modifing it, we can remove zone_mem_map. Signed-off-by:
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KAMEZAWA Hiroyuki authored
There are 3 memory models, FLATMEM, DISCONTIGMEM, SPARSEMEM. Each arch has its own page_to_pfn(), pfn_to_page() for each models. But most of them can use the same arithmetic. This patch adds asm-generic/memory_model.h, which includes generic page_to_pfn(), pfn_to_page() definitions for each memory model. When CONFIG_OUT_OF_LINE_PFN_TO_PAGE=y, out-of-line functions are used instead of macro. This is enabled by some archs and reduces text size. Signed-off-by:
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- Mar 25, 2006
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John Hawkes authored
The "rounded up to nearest power of 2 in size" algorithm in alloc_large_system_hash is not correct. As coded, it takes an otherwise acceptable power-of-2 value and doubles it. For example, we see the error if we boot with thash_entries=2097152 which produces a hash table with 4194304 entries. Signed-off-by:
John Hawkes <hawkes@sgi.com> Cc: Roland Dreier <rdreier@cisco.com> Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com> Signed-off-by:
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Anton Blanchard authored
In zone_pcp_init we print out all zones even if they are empty: On node 0 totalpages: 245760 DMA zone: 245760 pages, LIFO batch:31 DMA32 zone: 0 pages, LIFO batch:0 Normal zone: 0 pages, LIFO batch:0 HighMem zone: 0 pages, LIFO batch:0 To conserve dmesg space why not print only the non zero zones. Signed-off-by:
Anton Blanchard <anton@samba.org> Signed-off-by:
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- Mar 24, 2006
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Christoph Lameter authored
If we get under some memory pressure in a cpuset (we only scan zones that are in the cpuset for memory) then kswapd is woken up for all zones. This patch only wakes up kswapd in zones that are part of the current cpuset. Signed-off-by:
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- Mar 22, 2006
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Christoph Lameter authored
1. Only disable interrupts if there is actually something to free 2. Only dirty the pcp cacheline if we actually freed something. 3. Disable interrupts for each single pcp and not for cleaning all the pcps in all zones of a node. drain_node_pages is called every 2 seconds from cache_reap. This fix should avoid most disabling of interrupts. Signed-off-by:
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Andrew Morton authored
prep_zero_page() uses KM_USER0 and hence may not be used from IRQ context, at least for highmem pages. Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Christoph Lameter <christoph@lameter.com> Signed-off-by:
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Nick Piggin authored
Move the prep_ stuff into prep_new_page. Signed-off-by:
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Nick Piggin authored
set_page_count usage outside mm/ is limited to setting the refcount to 1. Remove set_page_count from outside mm/, and replace those users with init_page_count() and set_page_refcounted(). This allows more debug checking, and tighter control on how code is allowed to play around with page->_count. Signed-off-by:
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