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2008-02-05vmstat: remove prefetchChristoph Lameter1-9/+2
Remove the prefetch logic in order to avoid touching impossible per cpu areas. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Mike Travis <travis@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05Page allocator: get rid of the list of cold pagesChristoph Lameter1-18/+12
We have repeatedly discussed if the cold pages still have a point. There is one way to join the two lists: Use a single list and put the cold pages at the end and the hot pages at the beginning. That way a single list can serve for both types of allocations. The discussion of the RFC for this and Mel's measurements indicate that there may not be too much of a point left to having separate lists for hot and cold pages (see http://marc.info/?t=119492914200001&r=1&w=2). Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Martin Bligh <mbligh@mbligh.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05vmstat: small revisions to refresh_cpu_vm_stats()Christoph Lameter1-4/+16
1. Add comments explaining how the function can be called. 2. Collect global diffs in a local array and only spill them once into the global counters when the zone scan is finished. This means that we only touch each global counter once instead of each time we fold cpu counters into zone counters. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-11-14vmstat: fix section mismatch warningRandy Dunlap1-1/+1
Mark start_cpu_timer() as __cpuinit instead of __devinit. Fixes this section warning: WARNING: vmlinux.o(.text+0x60e53): Section mismatch: reference to .init.text:start_cpu_timer (between 'vmstat_cpuup_callback' and 'vmstat_show') Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Acked-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-17oom: change all_unreclaimable zone member to flagsDavid Rientjes1-1/+1
Convert the int all_unreclaimable member of struct zone to unsigned long flags. This can now be used to specify several different zone flags such as all_unreclaimable and reclaim_in_progress, which can now be removed and converted to a per-zone flag. Flags are set and cleared as follows: zone_set_flag(struct zone *zone, zone_flags_t flag) zone_clear_flag(struct zone *zone, zone_flags_t flag) Defines the first zone flags, ZONE_ALL_UNRECLAIMABLE and ZONE_RECLAIM_LOCKED, which have the same semantics as the old zone->all_unreclaimable and zone->reclaim_in_progress, respectively. Also converts all current users that set or clear either flag to use the new interface. Helper functions are defined to test the flags: int zone_is_all_unreclaimable(const struct zone *zone) int zone_is_reclaim_locked(const struct zone *zone) All flag operators are of the atomic variety because there are currently readers that are implemented that do not take zone->lock. [akpm@linux-foundation.org: add needed include] Cc: Andrea Arcangeli <andrea@suse.de> Acked-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16mm/vmstat.c: cleanupsAdrian Bunk1-18/+1
This patch contains the following cleanups: - make the needlessly global setup_vmstat() static - remove the unused refresh_vm_stats() Signed-off-by: Adrian Bunk <bunk@stusta.de> Acked-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16Print out statistics in relation to fragmentation avoidance to ↵Mel Gorman1-81/+205
/proc/pagetypeinfo This patch provides fragmentation avoidance statistics via /proc/pagetypeinfo. The information is collected only on request so there is no runtime overhead. The statistics are in three parts: The first part prints information on the size of blocks that pages are being grouped on and looks like Page block order: 10 Pages per block: 1024 The second part is a more detailed version of /proc/buddyinfo and looks like Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10 Node 0, zone DMA, type Unmovable 0 0 0 0 0 0 0 0 0 0 0 Node 0, zone DMA, type Reclaimable 1 0 0 0 0 0 0 0 0 0 0 Node 0, zone DMA, type Movable 0 0 0 0 0 0 0 0 0 0 0 Node 0, zone DMA, type Reserve 0 4 4 0 0 0 0 1 0 1 0 Node 0, zone Normal, type Unmovable 111 8 4 4 2 3 1 0 0 0 0 Node 0, zone Normal, type Reclaimable 293 89 8 0 0 0 0 0 0 0 0 Node 0, zone Normal, type Movable 1 6 13 9 7 6 3 0 0 0 0 Node 0, zone Normal, type Reserve 0 0 0 0 0 0 0 0 0 0 4 The third part looks like Number of blocks type Unmovable Reclaimable Movable Reserve Node 0, zone DMA 0 1 2 1 Node 0, zone Normal 3 17 94 4 To walk the zones within a node with interrupts disabled, walk_zones_in_node() is introduced and shared between /proc/buddyinfo, /proc/zoneinfo and /proc/pagetypeinfo to reduce code duplication. It seems specific to what vmstat.c requires but could be broken out as a general utility function in mmzone.c if there were other other potential users. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Andy Whitcroft <apw@shadowen.org> Acked-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-29Remove fs.h from mm.hAlexey Dobriyan1-0/+1
Remove fs.h from mm.h. For this, 1) Uninline vma_wants_writenotify(). It's pretty huge anyway. 2) Add back fs.h or less bloated headers (err.h) to files that need it. As result, on x86_64 allyesconfig, fs.h dependencies cut down from 3929 files rebuilt down to 3444 (-12.3%). Cross-compile tested without regressions on my two usual configs and (sigh): alpha arm-mx1ads mips-bigsur powerpc-ebony alpha-allnoconfig arm-neponset mips-capcella powerpc-g5 alpha-defconfig arm-netwinder mips-cobalt powerpc-holly alpha-up arm-netx mips-db1000 powerpc-iseries arm arm-ns9xxx mips-db1100 powerpc-linkstation arm-assabet arm-omap_h2_1610 mips-db1200 powerpc-lite5200 arm-at91rm9200dk arm-onearm mips-db1500 powerpc-maple arm-at91rm9200ek arm-picotux200 mips-db1550 powerpc-mpc7448_hpc2 arm-at91sam9260ek arm-pleb mips-ddb5477 powerpc-mpc8272_ads arm-at91sam9261ek arm-pnx4008 mips-decstation powerpc-mpc8313_rdb arm-at91sam9263ek arm-pxa255-idp mips-e55 powerpc-mpc832x_mds arm-at91sam9rlek arm-realview mips-emma2rh powerpc-mpc832x_rdb arm-ateb9200 arm-realview-smp mips-excite powerpc-mpc834x_itx arm-badge4 arm-rpc mips-fulong powerpc-mpc834x_itxgp arm-carmeva arm-s3c2410 mips-ip22 powerpc-mpc834x_mds arm-cerfcube arm-shannon mips-ip27 powerpc-mpc836x_mds arm-clps7500 arm-shark mips-ip32 powerpc-mpc8540_ads arm-collie arm-simpad mips-jazz powerpc-mpc8544_ds arm-corgi arm-spitz mips-jmr3927 powerpc-mpc8560_ads arm-csb337 arm-trizeps4 mips-malta powerpc-mpc8568mds arm-csb637 arm-versatile mips-mipssim powerpc-mpc85xx_cds arm-ebsa110 i386 mips-mpc30x powerpc-mpc8641_hpcn arm-edb7211 i386-allnoconfig mips-msp71xx powerpc-mpc866_ads arm-em_x270 i386-defconfig mips-ocelot powerpc-mpc885_ads arm-ep93xx i386-up mips-pb1100 powerpc-pasemi arm-footbridge ia64 mips-pb1500 powerpc-pmac32 arm-fortunet ia64-allnoconfig mips-pb1550 powerpc-ppc64 arm-h3600 ia64-bigsur mips-pnx8550-jbs powerpc-prpmc2800 arm-h7201 ia64-defconfig mips-pnx8550-stb810 powerpc-ps3 arm-h7202 ia64-gensparse mips-qemu powerpc-pseries arm-hackkit ia64-sim mips-rbhma4200 powerpc-up arm-integrator ia64-sn2 mips-rbhma4500 s390 arm-iop13xx ia64-tiger mips-rm200 s390-allnoconfig arm-iop32x ia64-up mips-sb1250-swarm s390-defconfig arm-iop33x ia64-zx1 mips-sead s390-up arm-ixp2000 m68k mips-tb0219 sparc arm-ixp23xx m68k-amiga mips-tb0226 sparc-allnoconfig arm-ixp4xx m68k-apollo mips-tb0287 sparc-defconfig arm-jornada720 m68k-atari mips-workpad sparc-up arm-kafa m68k-bvme6000 mips-wrppmc sparc64 arm-kb9202 m68k-hp300 mips-yosemite sparc64-allnoconfig arm-ks8695 m68k-mac parisc sparc64-defconfig arm-lart m68k-mvme147 parisc-allnoconfig sparc64-up arm-lpd270 m68k-mvme16x parisc-defconfig um-x86_64 arm-lpd7a400 m68k-q40 parisc-up x86_64 arm-lpd7a404 m68k-sun3 powerpc x86_64-allnoconfig arm-lubbock m68k-sun3x powerpc-cell x86_64-defconfig arm-lusl7200 mips powerpc-celleb x86_64-up arm-mainstone mips-atlas powerpc-chrp32 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17Create the ZONE_MOVABLE zoneMel Gorman1-1/+1
The following 8 patches against 2.6.20-mm2 create a zone called ZONE_MOVABLE that is only usable by allocations that specify both __GFP_HIGHMEM and __GFP_MOVABLE. This has the effect of keeping all non-movable pages within a single memory partition while allowing movable allocations to be satisfied from either partition. The patches may be applied with the list-based anti-fragmentation patches that groups pages together based on mobility. The size of the zone is determined by a kernelcore= parameter specified at boot-time. This specifies how much memory is usable by non-movable allocations and the remainder is used for ZONE_MOVABLE. Any range of pages within ZONE_MOVABLE can be released by migrating the pages or by reclaiming. When selecting a zone to take pages from for ZONE_MOVABLE, there are two things to consider. First, only memory from the highest populated zone is used for ZONE_MOVABLE. On the x86, this is probably going to be ZONE_HIGHMEM but it would be ZONE_DMA on ppc64 or possibly ZONE_DMA32 on x86_64. Second, the amount of memory usable by the kernel will be spread evenly throughout NUMA nodes where possible. If the nodes are not of equal size, the amount of memory usable by the kernel on some nodes may be greater than others. By default, the zone is not as useful for hugetlb allocations because they are pinned and non-migratable (currently at least). A sysctl is provided that allows huge pages to be allocated from that zone. This means that the huge page pool can be resized to the size of ZONE_MOVABLE during the lifetime of the system assuming that pages are not mlocked. Despite huge pages being non-movable, we do not introduce additional external fragmentation of note as huge pages are always the largest contiguous block we care about. Credit goes to Andy Whitcroft for catching a large variety of problems during review of the patches. This patch creates an additional zone, ZONE_MOVABLE. This zone is only usable by allocations which specify both __GFP_HIGHMEM and __GFP_MOVABLE. Hot-added memory continues to be placed in their existing destination as there is no mechanism to redirect them to a specific zone. [y-goto@jp.fujitsu.com: Fix section mismatch of memory hotplug related code] [akpm@linux-foundation.org: various fixes] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-06mm: fixup /proc/vmstat outputPeter Zijlstra1-1/+1
Line up the vmstat_text with zone_stat_item enum zone_stat_item { /* First 128 byte cacheline (assuming 64 bit words) */ NR_FREE_PAGES, NR_INACTIVE, NR_ACTIVE, We current have nr_active and nr_inactive reversed. [ "OK with patch, though using initializers canbe handy to prevent such things in future: static const char * const vmstat_text[] = { [NR_FREE_PAGES] = "nr_free_pages", ..." - Alexey ] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-21Detach sched.h from mm.hAlexey Dobriyan1-0/+1
First thing mm.h does is including sched.h solely for can_do_mlock() inline function which has "current" dereference inside. By dealing with can_do_mlock() mm.h can be detached from sched.h which is good. See below, why. This patch a) removes unconditional inclusion of sched.h from mm.h b) makes can_do_mlock() normal function in mm/mlock.c c) exports can_do_mlock() to not break compilation d) adds sched.h inclusions back to files that were getting it indirectly. e) adds less bloated headers to some files (asm/signal.h, jiffies.h) that were getting them indirectly Net result is: a) mm.h users would get less code to open, read, preprocess, parse, ... if they don't need sched.h b) sched.h stops being dependency for significant number of files: on x86_64 allmodconfig touching sched.h results in recompile of 4083 files, after patch it's only 3744 (-8.3%). Cross-compile tested on all arm defconfigs, all mips defconfigs, all powerpc defconfigs, alpha alpha-up arm i386 i386-up i386-defconfig i386-allnoconfig ia64 ia64-up m68k mips parisc parisc-up powerpc powerpc-up s390 s390-up sparc sparc-up sparc64 sparc64-up um-x86_64 x86_64 x86_64-up x86_64-defconfig x86_64-allnoconfig as well as my two usual configs. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-11VM statistics: Make timer deferrableChristoph Lameter1-1/+1
VM statistics updates do not matter if the kernel is in idle powersaving mode. So allow the timer to be deferred. It would be better though if we could switch the timer between deferrable and nondeferrable based on differentials present. The timer would start out nondeferrable and if we find that there were no updates in the last statistics interval then we would switch the timer to deferrable. If the timer later finds again that there are differentials then go to nondeferrable again. And yet another way would be to run the timer shortly before going to idle? The solution here means that the VM counters may be slightly off during idle since differentials may be still pending while the timer is deferred. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09Move remote node draining out of slab allocatorsChristoph Lameter1-5/+49
Currently the slab allocators contain callbacks into the page allocator to perform the draining of pagesets on remote nodes. This requires SLUB to have a whole subsystem in order to be compatible with SLAB. Moving node draining out of the slab allocators avoids a section of code in SLUB. Move the node draining so that is is done when the vm statistics are updated. At that point we are already touching all the cachelines with the pagesets of a processor. Add a expire counter there. If we have to update per zone or global vm statistics then assume that the pageset will require subsequent draining. The expire counter will be decremented on each vm stats update pass until it reaches zero. Then we will drain one batch from the pageset. The draining will cause vm counter updates which will then cause another expiration until the pcp is empty. So we will drain a batch every 3 seconds. Note that remote node draining is a somewhat esoteric feature that is required on large NUMA systems because otherwise significant portions of system memory can become trapped in pcp queues. The number of pcp is determined by the number of processors and nodes in a system. A system with 4 processors and 2 nodes has 8 pcps which is okay. But a system with 1024 processors and 512 nodes has 512k pcps with a high potential for large amount of memory being caught in them. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09Make vm statistics update interval configurableChristoph Lameter1-1/+3
Make it configurable. Code in mm makes the vm statistics intervals independent from the cache reaper use that opportunity to make it configurable. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09vmstat: use our own timer eventsChristoph Lameter1-4/+36
vmstat is currently using the cache reaper to periodically bring the statistics up to date. The cache reaper does only exists in SLUB as a way to provide compatibility with SLAB. This patch removes the vmstat calls from the slab allocators and provides its own handling. The advantage is also that we can use a different frequency for the updates. Refreshing vm stats is a pretty fast job so we can run this every second and stagger this by only one tick. This will lead to some overlap in large systems. F.e a system running at 250 HZ with 1024 processors will have 4 vm updates occurring at once. However, the vm stats update only accesses per node information. It is only necessary to stagger the vm statistics updates per processor in each node. Vm counter updates occurring on distant nodes will not cause cacheline contention. We could implement an alternate approach that runs the first processor on each node at the second and then each of the other processor on a node on a subsequent tick. That may be useful to keep a large amount of the second free of timer activity. Maybe the timer folks will have some feedback on this one? [jirislaby@gmail.com: add missing break] Cc: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Jiri Slaby <jirislaby@gmail.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09Add suspend-related notifications for CPU hotplugRafael J. Wysocki1-0/+3
Since nonboot CPUs are now disabled after tasks and devices have been frozen and the CPU hotplug infrastructure is used for this purpose, we need special CPU hotplug notifications that will help the CPU-hotplug-aware subsystems distinguish normal CPU hotplug events from CPU hotplug events related to a system-wide suspend or resume operation in progress. This patch introduces such notifications and causes them to be used during suspend and resume transitions. It also changes all of the CPU-hotplug-aware subsystems to take these notifications into consideration (for now they are handled in the same way as the corresponding "normal" ones). [oleg@tv-sign.ru: cleanups] Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: Gautham R Shenoy <ego@in.ibm.com> Cc: Pavel Machek <pavel@ucw.cz> Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11[PATCH] optional ZONE_DMA: optional ZONE_DMA in the VMChristoph Lameter1-1/+7
Make ZONE_DMA optional in core code. - ifdef all code for ZONE_DMA and related definitions following the example for ZONE_DMA32 and ZONE_HIGHMEM. - Without ZONE_DMA, ZONE_HIGHMEM and ZONE_DMA32 we get to a ZONES_SHIFT of 0. - Modify the VM statistics to work correctly without a DMA zone. - Modify slab to not create DMA slabs if there is no ZONE_DMA. [akpm@osdl.org: cleanup] [jdike@addtoit.com: build fix] [apw@shadowen.org: Simplify calculation of the number of bits we need for ZONES_SHIFT] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Andi Kleen <ak@suse.de> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Matthew Wilcox <willy@debian.org> Cc: James Bottomley <James.Bottomley@steeleye.com> Cc: Paul Mundt <lethal@linux-sh.org> Signed-off-by: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11[PATCH] Drop get_zone_counts()Christoph Lameter1-8/+0
Values are available via ZVC sums. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11[PATCH] Drop __get_zone_counts()Christoph Lameter1-8/+0
Values are readily available via ZVC per node and global sums. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11[PATCH] Reorder ZVCs according to cachelineChristoph Lameter1-2/+2
The global and per zone counter sums are in arrays of longs. Reorder the ZVCs so that the most frequently used ZVCs are put into the same cacheline. That way calculations of the global, node and per zone vm state touches only a single cacheline. This is mostly important for 64 bit systems were one 128 byte cacheline takes only 8 longs. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11[PATCH] Use ZVC for free_pagesChristoph Lameter1-16/+4
This is again simplifies some of the VM counter calculations through the use of the ZVC consolidated counters. [michal.k.k.piotrowski@gmail.com: build fix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Michal Piotrowski <michal.k.k.piotrowski@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11[PATCH] Use ZVC for inactive and active countsChristoph Lameter1-15/+13
The determination of the dirty ratio to determine writeback behavior is currently based on the number of total pages on the system. However, not all pages in the system may be dirtied. Thus the ratio is always too low and can never reach 100%. The ratio may be particularly skewed if large hugepage allocations, slab allocations or device driver buffers make large sections of memory not available anymore. In that case we may get into a situation in which f.e. the background writeback ratio of 40% cannot be reached anymore which leads to undesired writeback behavior. This patchset fixes that issue by determining the ratio based on the actual pages that may potentially be dirty. These are the pages on the active and the inactive list plus free pages. The problem with those counts has so far been that it is expensive to calculate these because counts from multiple nodes and multiple zones will have to be summed up. This patchset makes these counters ZVC counters. This means that a current sum per zone, per node and for the whole system is always available via global variables and not expensive anymore to calculate. The patchset results in some other good side effects: - Removal of the various functions that sum up free, active and inactive page counts - Cleanup of the functions that display information via the proc filesystem. This patch: The use of a ZVC for nr_inactive and nr_active allows a simplification of some counter operations. More ZVC functionality is used for sums etc in the following patches. [akpm@osdl.org: UP build fix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11[PATCH] /proc/zoneinfo: fix vm stats displayAndrew Morton1-6/+0
This early break prevents us from displaying info for the vm stats thresholds if the zone doesn't have any pages in its per-cpu pagesets. So my 800MB i386 box says: Node 0, zone DMA pages free 2365 min 16 low 20 high 24 active 0 inactive 0 scanned 0 (a: 0 i: 0) spanned 4096 present 4044 nr_anon_pages 0 nr_mapped 1 nr_file_pages 0 nr_slab_reclaimable 0 nr_slab_unreclaimable 0 nr_page_table_pages 0 nr_dirty 0 nr_writeback 0 nr_unstable 0 nr_bounce 0 nr_vmscan_write 0 protection: (0, 868, 868) pagesets all_unreclaimable: 0 prev_priority: 12 start_pfn: 0 Node 0, zone Normal pages free 199713 min 934 low 1167 high 1401 active 10215 inactive 4507 scanned 0 (a: 0 i: 0) spanned 225280 present 222420 nr_anon_pages 2685 nr_mapped 1110 nr_file_pages 12055 nr_slab_reclaimable 2216 nr_slab_unreclaimable 1527 nr_page_table_pages 213 nr_dirty 0 nr_writeback 0 nr_unstable 0 nr_bounce 0 nr_vmscan_write 0 protection: (0, 0, 0) pagesets cpu: 0 pcp: 0 count: 152 high: 186 batch: 31 cpu: 0 pcp: 1 count: 13 high: 62 batch: 15 vm stats threshold: 16 cpu: 1 pcp: 0 count: 34 high: 186 batch: 31 cpu: 1 pcp: 1 count: 10 high: 62 batch: 15 vm stats threshold: 16 all_unreclaimable: 0 prev_priority: 12 start_pfn: 4096 Just nuke all that search-for-the-first-non-empty-pageset code. Dunno why it was there in the first place.. Cc: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2006-12-07[PATCH] struct seq_operations and struct file_operations constificationHelge Deller1-4/+4
- move some file_operations structs into the .rodata section - move static strings from policy_types[] array into the .rodata section - fix generic seq_operations usages, so that those structs may be defined as "const" as well [akpm@osdl.org: couple of fixes] Signed-off-by: Helge Deller <deller@gmx.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07[PATCH] mm: cleanup indentation on switch for CPU operationsAndy Whitcroft1-7/+7
These patches introduced new switch statements which are indented contrary to the concensus in mm/*.c. Fix them up to match that concensus. [PATCH] node local per-cpu-pages [PATCH] ZVC: Scale thresholds depending on the size of the system commit e7c8d5c9955a4d2e88e36b640563f5d6d5aba48a commit df9ecaba3f152d1ea79f2a5e0b87505e03f47590 Signed-off-by: Andy Whitcroft <apw@shadowen.org> Cc: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-28[PATCH] vmscan: Fix temp_priority raceMartin Bligh1-2/+0
The temp_priority field in zone is racy, as we can walk through a reclaim path, and just before we copy it into prev_priority, it can be overwritten (say with DEF_PRIORITY) by another reclaimer. The same bug is contained in both try_to_free_pages and balance_pgdat, but it is fixed slightly differently. In balance_pgdat, we keep a separate priority record per zone in a local array. In try_to_free_pages there is no need to do this, as the priority level is the same for all zones that we reclaim from. Impact of this bug is that temp_priority is copied into prev_priority, and setting this artificially high causes reclaimers to set distress artificially low. They then fail to reclaim mapped pages, when they are, in fact, under severe memory pressure (their priority may be as low as 0). This causes the OOM killer to fire incorrectly. From: Andrew Morton <akpm@osdl.org> __zone_reclaim() isn't modifying zone->prev_priority. But zone->prev_priority is used in the decision whether or not to bring mapped pages onto the inactive list. Hence there's a risk here that __zone_reclaim() will fail because zone->prev_priority ir large (ie: low urgency) and lots of mapped pages end up stuck on the active list. Fix that up by decreasing (ie making more urgent) zone->prev_priority as __zone_reclaim() scans the zone's pages. This bug perhaps explains why ZONE_RECLAIM_PRIORITY was created. It should be possible to remove that now, and to just start out at DEF_PRIORITY? Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Christoph Lameter <clameter@engr.sgi.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-04Remove all inclusions of <linux/config.h>Dave Jones1-1/+0
kbuild explicitly includes this at build time. Signed-off-by: Dave Jones <davej@redhat.com>
2006-09-27[PATCH] zone_statistics: Use hot node instead of cold zone_pgdatChristoph Lameter1-1/+1
Now that we have the node in the hot zone of struct zone we can avoid accessing zone_pgdat in zone_statistics. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-27[PATCH] vm: add per-zone writeout counterAndrew Morton1-0/+1
The VM is supposed to minimise the number of pages which get written off the LRU (for IO scheduling efficiency, and for high reclaim-success rates). But we don't actually have a clear way of showing how true this is. So add `nr_vmscan_write' to /proc/vmstat and /proc/zoneinfo - the number of pages which have been written by the vm scanner in this zone and globally. Cc: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-26[PATCH] ZVC: Support NR_SLAB_RECLAIMABLE / NR_SLAB_UNRECLAIMABLEChristoph Lameter1-1/+2
Remove the atomic counter for slab_reclaim_pages and replace the counter and NR_SLAB with two ZVC counter that account for unreclaimable and reclaimable slab pages: NR_SLAB_RECLAIMABLE and NR_SLAB_UNRECLAIMABLE. Change the check in vmscan.c to refer to to NR_SLAB_RECLAIMABLE. The intend seems to be to check for slab pages that could be freed. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-26[PATCH] mm: do not check unpopulated zones for draining and counter updatesChristoph Lameter1-0/+3
If a zone is unpopulated then we do not need to check for pages that are to be drained and also not for vm counters that may need to be updated. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-26[PATCH] reduce MAX_NR_ZONES: remove display of counters for unconfigured zonesChristoph Lameter1-23/+20
eventcounters: Do not display counters for zones that are not available on an arch Do not define or display counters for the DMA32 and the HIGHMEM zone if such zones were not configured. [akpm@osdl.org: s390 fix] [heiko.carstens@de.ibm.com: s390 fix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-01[PATCH] ZVC: Scale thresholds depending on the size of the systemChristoph Lameter1-20/+119
The ZVC counter update threshold is currently set to a fixed value of 32. This patch sets up the threshold depending on the number of processors and the sizes of the zones in the system. With the current threshold of 32, I was able to observe slight contention when more than 130-140 processors concurrently updated the counters. The contention vanished when I either increased the threshold to 64 or used Andrew's idea of overstepping the interval (see ZVC overstep patch). However, we saw contention again at 220-230 processors. So we need higher values for larger systems. But the current default is already a bit of an overkill for smaller systems. Some systems have tiny zones where precision matters. For example i386 and x86_64 have 16M DMA zones and either 900M ZONE_NORMAL or ZONE_DMA32. These are even present on SMP and NUMA systems. The patch here sets up a threshold based on the number of processors in the system and the size of the zone that these counters are used for. The threshold should grow logarithmically, so we use fls() as an easy approximation. Results of tests on a system with 1024 processors (4TB RAM) The following output is from a test allocating 1GB of memory concurrently on each processor (Forking the process. So contention on mmap_sem and the pte locks is not a factor): X MIN TYPE: CPUS WALL WALL SYS USER TOTCPU fork 1 0.552 0.552 0.540 0.012 0.552 fork 4 0.552 0.548 2.164 0.036 2.200 fork 16 0.564 0.548 8.812 0.164 8.976 fork 128 0.580 0.572 72.204 1.208 73.412 fork 256 1.300 0.660 310.400 2.160 312.560 fork 512 3.512 0.696 1526.836 4.816 1531.652 fork 1020 20.024 0.700 17243.176 6.688 17249.863 So a threshold of 32 is fine up to 128 processors. At 256 processors contention becomes a factor. Overstepping the counter (earlier patch) improves the numbers a bit: fork 4 0.552 0.548 2.164 0.040 2.204 fork 16 0.552 0.548 8.640 0.148 8.788 fork 128 0.556 0.548 69.676 0.956 70.632 fork 256 0.876 0.636 212.468 2.108 214.576 fork 512 2.276 0.672 997.324 4.260 1001.584 fork 1020 13.564 0.680 11586.436 6.088 11592.523 Still contention at 512 and 1020. Contention at 1020 is down by a third. 256 still has a slight bit of contention. After this patch the counter threshold will be set to 125 which reduces contention significantly: fork 128 0.560 0.548 69.776 0.932 70.708 fork 256 0.636 0.556 143.460 2.036 145.496 fork 512 0.640 0.548 284.244 4.236 288.480 fork 1020 1.500 0.588 1326.152 8.892 1335.044 [akpm@osdl.org: !SMP build fix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-01[PATCH] ZVC: Overstep countersChristoph Lameter1-15/+5
Increments and decrements are usually grouped rather than mixed. We can optimize the inc and dec functions for that case. Increment and decrement the counters by 50% more than the threshold in those cases and set the differential accordingly. This decreases the need to update the atomic counters. The idea came originally from Andrew Morton. The overstepping alone was sufficient to address the contention issue found when updating the global and the per zone counters from 160 processors. Also remove some code in dec_zone_page_state. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-10[PATCH] vmstat: export all_vm_events()Heiko Carstens1-0/+1
Add missing EXPORT_SYMBOL for all_vm_events(). Git commit f8891e5e1f93a128c3900f82035e8541357896a7 caused this: Building modules, stage 2. MODPOST WARNING: "all_vm_events" [arch/s390/appldata/appldata_mem.ko] undefined! CC arch/s390/appldata/appldata_mem.mod.o Cc: Christoph Lameter <christoph@lameter.com> Cc: Gerald Schaefer <geraldsc@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-30[PATCH] Light weight event countersChristoph Lameter1-82/+89
The remaining counters in page_state after the zoned VM counter patches have been applied are all just for show in /proc/vmstat. They have no essential function for the VM. We use a simple increment of per cpu variables. In order to avoid the most severe races we disable preempt. Preempt does not prevent the race between an increment and an interrupt handler incrementing the same statistics counter. However, that race is exceedingly rare, we may only loose one increment or so and there is no requirement (at least not in kernel) that the vm event counters have to be accurate. In the non preempt case this results in a simple increment for each counter. For many architectures this will be reduced by the compiler to a single instruction. This single instruction is atomic for i386 and x86_64. And therefore even the rare race condition in an interrupt is avoided for both architectures in most cases. The patchset also adds an off switch for embedded systems that allows a building of linux kernels without these counters. The implementation of these counters is through inline code that hopefully results in only a single instruction increment instruction being emitted (i386, x86_64) or in the increment being hidden though instruction concurrency (EPIC architectures such as ia64 can get that done). Benefits: - VM event counter operations usually reduce to a single inline instruction on i386 and x86_64. - No interrupt disable, only preempt disable for the preempt case. Preempt disable can also be avoided by moving the counter into a spinlock. - Handling is similar to zoned VM counters. - Simple and easily extendable. - Can be omitted to reduce memory use for embedded use. References: RFC http://marc.theaimsgroup.com/?l=linux-kernel&m=113512330605497&w=2 RFC http://marc.theaimsgroup.com/?l=linux-kernel&m=114988082814934&w=2 local_t http://marc.theaimsgroup.com/?l=linux-kernel&m=114991748606690&w=2 V2 http://marc.theaimsgroup.com/?t=115014808400007&r=1&w=2 V3 http://marc.theaimsgroup.com/?l=linux-kernel&m=115024767022346&w=2 V4 http://marc.theaimsgroup.com/?l=linux-kernel&m=115047968808926&w=2 Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-30[PATCH] Use Zoned VM Counters for NUMA statisticsChristoph Lameter1-26/+47
The numa statistics are really event counters. But they are per node and so we have had special treatment for these counters through additional fields on the pcp structure. We can now use the per zone nature of the zoned VM counters to realize these. This will shrink the size of the pcp structure on NUMA systems. We will have some room to add additional per zone counters that will all still fit in the same cacheline. Bits Prior pcp size Size after patch We can add ------------------------------------------------------------------ 64 128 bytes (16 words) 80 bytes (10 words) 48 32 76 bytes (19 words) 56 bytes (14 words) 8 (64 byte cacheline) 72 (128 byte) Remove the special statistics for numa and replace them with zoned vm counters. This has the side effect that global sums of these events now show up in /proc/vmstat. Also take the opportunity to move the zone_statistics() function from page_alloc.c into vmstat.c. Discussions: V2 http://marc.theaimsgroup.com/?t=115048227000002&r=1&w=2 Signed-off-by: Christoph Lameter <clameter@sgi.com> Acked-by: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-30[PATCH] zoned-vm-counters: remove read_page_state()Andrew Morton1-14/+0
No callers. Cc: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-30[PATCH] zoned vm counters: conversion of nr_bounce to per zone counterChristoph Lameter1-1/+1
Conversion of nr_bounce to a per zone counter nr_bounce is only used for proc output. So it could be left as an event counter. However, the event counters may not be accurate and nr_bounce is categorizing types of pages in a zone. So we really need this to also be a per zone counter. [akpm@osdl.org: bugfix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-30[PATCH] zoned vm counters: conversion of nr_unstable to per zone counterChristoph Lameter1-24/+1
Conversion of nr_unstable to a per zone counter We need to do some special modifications to the nfs code since there are multiple cases of disposition and we need to have a page ref for proper accounting. This converts the last critical page state of the VM and therefore we need to remove several functions that were depending on GET_PAGE_STATE_LAST in order to make the kernel compile again. We are only left with event type counters in page state. [akpm@osdl.org: bugfixes] 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>
2006-06-30[PATCH] zoned vm counters: conversion of nr_writeback to per zone counterChristoph Lameter1-1/+1
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>
2006-06-30[PATCH] zoned vm counters: conversion of nr_dirty to per zone counterChristoph Lameter1-1/+1
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: 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>
2006-06-30[PATCH] zoned vm counters: conversion of nr_pagetables to per zone counterChristoph Lameter1-1/+1
Conversion of nr_page_table_pages to a per zone counter [akpm@osdl.org: bugfix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-30[PATCH] zoned vm counters: conversion of nr_slab to per zone counterChristoph Lameter1-1/+1
- 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: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-30[PATCH] zoned vm counters: split NR_ANON_PAGES off from NR_FILE_MAPPEDChristoph Lameter1-0/+1
The current NR_FILE_MAPPED is used by zone reclaim and the dirty load calculation as the number of mapped pagecache pages. However, that is not true. NR_FILE_MAPPED includes the mapped anonymous pages. This patch separates those and therefore allows an accurate tracking of the anonymous pages per zone. It then becomes possible to determine the number of unmapped pages per zone and we can avoid scanning for unmapped pages if there are none. Also it may now be possible to determine the mapped/unmapped ratio in get_dirty_limit. Isnt the number of anonymous pages irrelevant in that calculation? Note that this will change the meaning of the number of mapped pages reported in /proc/vmstat /proc/meminfo and in the per node statistics. This may affect user space tools that monitor these counters! NR_FILE_MAPPED works like NR_FILE_DIRTY. It is only valid for pagecache pages. 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>
2006-06-30[PATCH] zoned vm counters: conversion of nr_pagecache to per zone counterChristoph Lameter1-6/+1
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: 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>
2006-06-30[PATCH] zoned vm counters: convert nr_mapped to per zone counterChristoph Lameter1-1/+1
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: 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>
2006-06-30[PATCH] zoned vm counters: basic ZVC (zoned vm counter) implementationChristoph Lameter1-4/+214
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: 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>
2006-06-30[PATCH] zoned vm counters: create vmstat.c/.h from page_alloc.c/.hChristoph Lameter1-0/+417
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: Christoph Lameter <clameter@sgi.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.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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