- 01 Nov, 2011 40 commits
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H Hartley Sweeten authored
Quiet the sparse noise: warning: symbol 'khugepaged_scan' was not declared. Should it be static? warning: context imbalance in 'khugepaged_scan_mm_slot' - unexpected unlock Signed-off-by:
H Hartley Sweeten <hsweeten@visionengravers.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <jweiner@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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H Hartley Sweeten authored
Quiet the spares noise: warning: symbol 'default_policy' was not declared. Should it be static? Signed-off-by:
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H Hartley Sweeten authored
Quiet the following sparse noise: warning: symbol 'swap_token_memcg' was not declared. Should it be static? Signed-off-by:
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H Hartley Sweeten authored
Quiet the following sparse noise in this file: warning: symbol 'memblock_overlaps_region' was not declared. Should it be static? Signed-off-by:
H Hartley Sweeten <hsweeten@visionengravers,com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: "H. Peter Anvin" <hpa@linux.intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Tomi Valkeinen <tomi.valkeinen@nokia.com> Signed-off-by:
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Johannes Weiner authored
At one point, anonymous pages were supposed to go on the unevictable list when no swap space was configured, and the idea was to manually rescue those pages after adding swap and making them evictable again. But nowadays, swap-backed pages on the anon LRU list are not scanned without available swap space anyway, so there is no point in moving them to a separate list anymore. The manual rescue could also be used in case pages were stranded on the unevictable list due to race conditions. But the code has been around for a while now and newly discovered bugs should be properly reported and dealt with instead of relying on such a manual fixup. In addition to the lack of a usecase, the sysfs interface to rescue pages from a specific NUMA node has been broken since its introduction, so it's unlikely that anybody ever relied on that. This patch removes the functionality behind the sysctl and the node-interface and emits a one-time warning when somebody tries to access either of them. Signed-off-by:
Johannes Weiner <jweiner@redhat.com> Reported-by:
Kautuk Consul <consul.kautuk@gmail.com> Reviewed-by:
Minchan Kim <minchan.kim@gmail.com> Acked-by:
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by:
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Kautuk Consul authored
write_scan_unevictable_node() checks the value req returned by strict_strtoul() and returns 1 if req is 0. However, when strict_strtoul() returns 0, it means successful conversion of buf to unsigned long. Due to this, the function was not proceeding to scan the zones for unevictable pages even though we write a valid value to the scan_unevictable_pages sys file. Change this check slightly to check for invalid value in buf as well as 0 value stored in res after successful conversion via strict_strtoul. In both cases, we do not perform the scanning of this node's zones. Signed-off-by:
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Li Haifeng authored
Signed-off-by:
Li Haifeng <omycle@gmail.com> Signed-off-by:
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Kyungmin Park authored
There's no compact_zone_order() user outside file scope, so make it static. Signed-off-by:
Kyungmin Park <kyungmin.park@samsung.com> Acked-by:
David Rientjes <rientjes@google.com> Reviewed-by:
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Dean Nelson authored
Commit fb46e735 ("HWPOISON: Convert pr_debugs to pr_info) authored by Andi Kleen converted a number of pr_debug()s to pr_info()s. About the same time additional code with pr_debug()s was added by two other commits 8c6c2ecb ("HWPOSION, hugetlb: recover from free hugepage error when !MF_COUNT_INCREASED") and d950b958 ("HWPOISON, hugetlb: soft offlining for hugepage"). And these pr_debug()s failed to get converted to pr_info()s. This patch converts them as well. And does some minor related whitespace cleanup. Signed-off-by:
Dean Nelson <dnelson@redhat.com> Reviewed-by:
Andi Kleen <ak@linux.intel.com> Signed-off-by:
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Tao Ma authored
On the ext4 mailing list[1], we got some report about errors in __find_get_block_slow(), but the information is very limited. If the device information is given, we can know the name of the sick volume. Futhermore, we can get the corresponding status of that block(group, inode block etc) by analyzing the disk layout. [1] http://marc.info/?l=linux-ext4&m=131379831421147&w=2Signed-off-by:
Tao Ma <boyu.mt@taobao.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Theodore Ts'o <tytso@mit.edu> Signed-off-by:
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Kautuk Consul authored
The ret variable is really not needed in mm_take_all_locks(). Signed-off-by:
Michal Hocko <mhocko@suse.cz> Signed-off-by:
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Mikulas Patocka authored
The callback must not return -1 when nr_to_scan is zero. Fix the bug in fs/super.c and add this requirement to the callback specification. Signed-off-by:
Mikulas Patocka <mpatocka@redhat.com> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by:
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Andrew Morton authored
fiddle wording Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by:
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Wanlong Gao authored
try_to_unmap_one() is called by try_to_unmap_ksm(), too. Signed-off-by:
Wanlong Gao <gaowanlong@cn.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by:
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Joe Perches authored
Some vmalloc failure paths do not report OOM conditions. Add warn_alloc_failed, which also does a dump_stack, to those failure paths. This allows more site specific vmalloc failure logging message printks to be removed. Signed-off-by:
Joe Perches <joe@perches.com> Signed-off-by:
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Alex,Shi authored
There 2 places to read pgdat in kswapd. One is return from a successful balance, another is waked up from kswapd sleeping. The new_order and new_classzone_idx represent the balance input order and classzone_idx. But current new_order and new_classzone_idx are not assigned after kswapd_try_to_sleep(), that will cause a bug in the following scenario. 1: after a successful balance, kswapd goes to sleep, and new_order = 0; new_classzone_idx = __MAX_NR_ZONES - 1; 2: kswapd waked up with order = 3 and classzone_idx = ZONE_NORMAL 3: in the balance_pgdat() running, a new balance wakeup happened with order = 5, and classzone_idx = ZONE_NORMAL 4: the first wakeup(order = 3) finished successufly, return order = 3 but, the new_order is still 0, so, this balancing will be treated as a failed balance. And then the second tighter balancing will be missed. So, to avoid the above problem, the new_order and new_classzone_idx need to be assigned for later successful comparison. Signed-off-by:
Alex Shi <alex.shi@intel.com> Acked-by:
Mel Gorman <mgorman@suse.de> Reviewed-by:
Pádraig Brady <P@draigBrady.com> Signed-off-by:
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Jonghwan Choi authored
warning: function 'memblock_memory_can_coalesce' with external linkage has definition. Signed-off-by:
Jonghwan Choi <jhbird.choi@samsung.com> Signed-off-by:
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Alex,Shi authored
In commit 215ddd66 ("mm: vmscan: only read new_classzone_idx from pgdat when reclaiming successfully") , Mel Gorman said kswapd is better to sleep after a unsuccessful balancing if there is tighter reclaim request pending in the balancing. But in the following scenario, kswapd do something that is not matched our expectation. The patch fixes this issue. 1, Read pgdat request A (classzone_idx, order = 3) 2, balance_pgdat() 3, During pgdat, a new pgdat request B (classzone_idx, order = 5) is placed 4, balance_pgdat() returns but failed since returned order = 0 5, pgdat of request A assigned to balance_pgdat(), and do balancing again. While the expectation behavior of kswapd should try to sleep. Signed-off-by:
Tim Chen <tim.c.chen@linux.intel.com> Acked-by:
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Akinobu Mita authored
This adds support for highmem pages poisoning and verification to the debug-pagealloc feature for no-architecture support. [akpm@linux-foundation.org: remove unneeded preempt_disable/enable] Signed-off-by:
Akinobu Mita <akinobu.mita@gmail.com> Signed-off-by:
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Joe Perches authored
Add __attribute__((format (printf...) to the function to validate format and arguments. Use vsprintf extension %pV to avoid any possible message interleaving. Coalesce format string. Convert printks/pr_warning to pr_warn. [akpm@linux-foundation.org: use the __printf() macro] Signed-off-by:
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Sonic Zhang authored
On NOMMU architectures, if physical memory doesn't start from 0, ARCH_PFN_OFFSET is defined to generate page index in mem_map array. Because virtual address is equal to physical address, PAGE_OFFSET is always 0. virt_to_page and page_to_virt should not index page by PAGE_OFFSET directly. Signed-off-by:
Sonic Zhang <sonic.zhang@analog.com> Cc: Greg Ungerer <gerg@snapgear.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: David Howells <dhowells@redhat.com> Signed-off-by:
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Andrea Arcangeli authored
This adds THP support to mremap (decreases the number of split_huge_page() calls). Here are also some benchmarks with a proggy like this: === #define _GNU_SOURCE #include <sys/mman.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #include <sys/time.h> #define SIZE (5UL*1024*1024*1024) int main() { static struct timeval oldstamp, newstamp; long diffsec; char *p, *p2, *p3, *p4; if (posix_memalign((void **)&p, 2*1024*1024, SIZE)) perror("memalign"), exit(1); if (posix_memalign((void **)&p2, 2*1024*1024, SIZE)) perror("memalign"), exit(1); if (posix_memalign((void **)&p3, 2*1024*1024, 4096)) perror("memalign"), exit(1); memset(p, 0xff, SIZE); memset(p2, 0xff, SIZE); memset(p3, 0x77, 4096); gettimeofday(&oldstamp, NULL); p4 = mremap(p, SIZE, SIZE, MREMAP_FIXED|MREMAP_MAYMOVE, p3); gettimeofday(&newstamp, NULL); diffsec = newstamp.tv_sec - oldstamp.tv_sec; diffsec = newstamp.tv_usec - oldstamp.tv_usec + 1000000 * diffsec; printf("usec %ld\n", diffsec); if (p == MAP_FAILED || p4 != p3) //if (p == MAP_FAILED) perror("mremap"), exit(1); if (memcmp(p4, p2, SIZE)) printf("mremap bug\n"), exit(1); printf("ok\n"); return 0; } === THP on Performance counter stats for './largepage13' (3 runs): 69195836 dTLB-loads ( +- 3.546% ) (scaled from 50.30%) 60708 dTLB-load-misses ( +- 11.776% ) (scaled from 52.62%) 676266476 dTLB-stores ( +- 5.654% ) (scaled from 69.54%) 29856 dTLB-store-misses ( +- 4.081% ) (scaled from 89.22%) 1055848782 iTLB-loads ( +- 4.526% ) (scaled from 80.18%) 8689 iTLB-load-misses ( +- 2.987% ) (scaled from 58.20%) 7.314454164 seconds time elapsed ( +- 0.023% ) THP off Performance counter stats for './largepage13' (3 runs): 1967379311 dTLB-loads ( +- 0.506% ) (scaled from 60.59%) 9238687 dTLB-load-misses ( +- 22.547% ) (scaled from 61.87%) 2014239444 dTLB-stores ( +- 0.692% ) (scaled from 60.40%) 3312335 dTLB-store-misses ( +- 7.304% ) (scaled from 67.60%) 6764372065 iTLB-loads ( +- 0.925% ) (scaled from 79.00%) 8202 iTLB-load-misses ( +- 0.475% ) (scaled from 70.55%) 9.693655243 seconds time elapsed ( +- 0.069% ) grep thp /proc/vmstat thp_fault_alloc 35849 thp_fault_fallback 0 thp_collapse_alloc 3 thp_collapse_alloc_failed 0 thp_split 0 thp_split 0 confirms no thp split despite plenty of hugepages allocated. The measurement of only the mremap time (so excluding the 3 long memset and final long 10GB memory accessing memcmp): THP on usec 14824 usec 14862 usec 14859 THP off usec 256416 usec 255981 usec 255847 With an older kernel without the mremap optimizations (the below patch optimizes the non THP version too). THP on usec 392107 usec 390237 usec 404124 THP off usec 444294 usec 445237 usec 445820 I guess with a threaded program that sends more IPI on large SMP it'd create an even larger difference. All debug options are off except DEBUG_VM to avoid skewing the results. The only problem for native 2M mremap like it happens above both the source and destination address must be 2M aligned or the hugepmd can't be moved without a split but that is an hardware limitation. [akpm@linux-foundation.org: coding-style nitpicking] Signed-off-by:Andrea Arcangeli <aarcange@redhat.com> Acked-by:
Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by:
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Andrea Arcangeli authored
This replaces ptep_clear_flush() with ptep_get_and_clear() and a single flush_tlb_range() at the end of the loop, to avoid sending one IPI for each page. The mmu_notifier_invalidate_range_start/end section is enlarged accordingly but this is not going to fundamentally change things. It was more by accident that the region under mremap was for the most part still available for secondary MMUs: the primary MMU was never allowed to reliably access that region for the duration of the mremap (modulo trapping SIGSEGV on the old address range which sounds unpractical and flakey). If users wants secondary MMUs not to lose access to a large region under mremap they should reduce the mremap size accordingly in userland and run multiple calls. Overall this will run faster so it's actually going to reduce the time the region is under mremap for the primary MMU which should provide a net benefit to apps. For KVM this is a noop because the guest physical memory is never mremapped, there's just no point it ever moving it while guest runs. One target of this optimization is JVM GC (so unrelated to the mmu notifier logic). Signed-off-by:
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Andrea Arcangeli authored
Using "- 1" relies on the old_end to be page aligned and PAGE_SIZE > 1, those are reasonable requirements but the check remains obscure and it looks more like an off by one error than an overflow check. This I feel will improve readability. Signed-off-by:
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Sam Ravnborg authored
With the NO_BOOTMEM symbol added architectures may now use the following syntax to tell that they do not need bootmem: select NO_BOOTMEM This is much more convinient than adding a new kconfig symbol which was otherwise required. Adding this symbol does not conflict with the architctures that already define their own symbol. Signed-off-by:
Sam Ravnborg <sam@ravnborg.org> Cc: Yinghai Lu <yinghai@kernel.org> Acked-by:
Tejun Heo <tj@kernel.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by:
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Sam Ravnborg authored
SPARC32 require access to the start address. Add a new helper memblock_start_of_DRAM() to give access to the address of the first memblock - which contains the lowest address. The awkward name was chosen to match the already present memblock_end_of_DRAM(). Signed-off-by:
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Mitsuo Hayasaka authored
The /proc/vmallocinfo shows information about vmalloc allocations in vmlist that is a linklist of vm_struct. It, however, may access pages field of vm_struct where a page was not allocated. This results in a null pointer access and leads to a kernel panic. Why this happens: In __vmalloc_node_range() called from vmalloc(), newly allocated vm_struct is added to vmlist at __get_vm_area_node() and then, some fields of vm_struct such as nr_pages and pages are set at __vmalloc_area_node(). In other words, it is added to vmlist before it is fully initialized. At the same time, when the /proc/vmallocinfo is read, it accesses the pages field of vm_struct according to the nr_pages field at show_numa_info(). Thus, a null pointer access happens. The patch adds the newly allocated vm_struct to the vmlist *after* it is fully initialized. So, it can avoid accessing the pages field with unallocated page when show_numa_info() is called. Signed-off-by:
Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: David Rientjes <rientjes@google.com> Cc: Namhyung Kim <namhyung@gmail.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: <stable@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by:
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Akinobu Mita authored
Use newly introduced memchr_inv() for page verification. Signed-off-by:
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Akinobu Mita authored
memchr_inv() is mainly used to check whether the whole buffer is filled with just a specified byte. The function name and prototype are stolen from logfs and the implementation is from SLUB. Signed-off-by:
Christoph Lameter <cl@linux-foundation.org> Acked-by:
Pekka Enberg <penberg@kernel.org> Cc: Matt Mackall <mpm@selenic.com> Acked-by:
Joern Engel <joern@logfs.org> Cc: Marcin Slusarz <marcin.slusarz@gmail.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by:
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Akinobu Mita authored
printk_ratelimit() should not be used, because it shares ratelimiting state with all other unrelated printk_ratelimit() callsites. Signed-off-by:
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Shaohua Li authored
It's possible a zone watermark is ok when entering the balance_pgdat() loop, while the zone is within the requested classzone_idx. Count pages from this zone into `balanced'. In this way, we can skip shrinking zones too much for high order allocation. Signed-off-by:
Shaohua Li <shaohua.li@intel.com> Acked-by:
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Mel Gorman authored
When direct reclaim encounters a dirty page, it gets recycled around the LRU for another cycle. This patch marks the page PageReclaim similar to deactivate_page() so that the page gets reclaimed almost immediately after the page gets cleaned. This is to avoid reclaiming clean pages that are younger than a dirty page encountered at the end of the LRU that might have been something like a use-once page. Signed-off-by:
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Mel Gorman authored
Workloads that are allocating frequently and writing files place a large number of dirty pages on the LRU. With use-once logic, it is possible for them to reach the end of the LRU quickly requiring the reclaimer to scan more to find clean pages. Ordinarily, processes that are dirtying memory will get throttled by dirty balancing but this is a global heuristic and does not take into account that LRUs are maintained on a per-zone basis. This can lead to a situation whereby reclaim is scanning heavily, skipping over a large number of pages under writeback and recycling them around the LRU consuming CPU. This patch checks how many of the number of pages isolated from the LRU were dirty and under writeback. If a percentage of them under writeback, the process will be throttled if a backing device or the zone is congested. Note that this applies whether it is anonymous or file-backed pages that are under writeback meaning that swapping is potentially throttled. This is intentional due to the fact if the swap device is congested, scanning more pages and dispatching more IO is not going to help matters. The percentage that must be in writeback depends on the priority. At default priority, all of them must be dirty. At DEF_PRIORITY-1, 50% of them must be, DEF_PRIORITY-2, 25% etc. i.e. as pressure increases the greater the likelihood the process will get throttled to allow the flusher threads to make some progress. Signed-off-by:
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Mel Gorman authored
It is preferable that no dirty pages are dispatched for cleaning from the page reclaim path. At normal priorities, this patch prevents kswapd writing pages. However, page reclaim does have a requirement that pages be freed in a particular zone. If it is failing to make sufficient progress (reclaiming < SWAP_CLUSTER_MAX at any priority priority), the priority is raised to scan more pages. A priority of DEF_PRIORITY - 3 is considered to be the point where kswapd is getting into trouble reclaiming pages. If this priority is reached, kswapd will dispatch pages for writing. Signed-off-by:
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Mel Gorman authored
Direct reclaim should never writeback pages. Warn if an attempt is made. Signed-off-by:
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Mel Gorman authored
Direct reclaim should never writeback pages. For now, handle the situation and warn about it. Ultimately, this will be a BUG_ON. Signed-off-by:
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Mel Gorman authored
Lumpy reclaim worked with two passes - the first which queued pages for IO and the second which waited on writeback. As direct reclaim can no longer write pages there is some dead code. This patch removes it but direct reclaim will continue to wait on pages under writeback while in synchronous reclaim mode. Signed-off-by:
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Mel Gorman authored
Testing from the XFS folk revealed that there is still too much I/O from the end of the LRU in kswapd. Previously it was considered acceptable by VM people for a small number of pages to be written back from reclaim with testing generally showing about 0.3% of pages reclaimed were written back (higher if memory was low). That writing back a small number of pages is ok has been heavily disputed for quite some time and Dave Chinner explained it well; It doesn't have to be a very high number to be a problem. IO is orders of magnitude slower than the CPU time it takes to flush a page, so the cost of making a bad flush decision is very high. And single page writeback from the LRU is almost always a bad flush decision. To complicate matters, filesystems respond very differently to requests from reclaim according to Christoph Hellwig; xfs tries to write it back if the requester is kswapd ext4 ignores the request if it's a delayed allocation btrfs ignores the request As a result, each filesystem has different performance characteristics when under memory pressure and there are many pages being dirtied. In some cases, the request is ignored entirely so the VM cannot depend on the IO being dispatched. The objective of this series is to reduce writing of filesystem-backed pages from reclaim, play nicely with writeback that is already in progress and throttle reclaim appropriately when writeback pages are encountered. The assumption is that the flushers will always write pages faster than if reclaim issues the IO. A secondary goal is to avoid the problem whereby direct reclaim splices two potentially deep call stacks together. There is a potential new problem as reclaim has less control over how long before a page in a particularly zone or container is cleaned and direct reclaimers depend on kswapd or flusher threads to do the necessary work. However, as filesystems sometimes ignore direct reclaim requests already, it is not expected to be a serious issue. Patch 1 disables writeback of filesystem pages from direct reclaim entirely. Anonymous pages are still written. Patch 2 removes dead code in lumpy reclaim as it is no longer able to synchronously write pages. This hurts lumpy reclaim but there is an expectation that compaction is used for hugepage allocations these days and lumpy reclaim's days are numbered. Patches 3-4 add warnings to XFS and ext4 if called from direct reclaim. With patch 1, this "never happens" and is intended to catch regressions in this logic in the future. Patch 5 disables writeback of filesystem pages from kswapd unless the priority is raised to the point where kswapd is considered to be in trouble. Patch 6 throttles reclaimers if too many dirty pages are being encountered and the zones or backing devices are congested. Patch 7 invalidates dirty pages found at the end of the LRU so they are reclaimed quickly after being written back rather than waiting for a reclaimer to find them I consider this series to be orthogonal to the writeback work but it is worth noting that the writeback work affects the viability of patch 8 in particular. I tested this on ext4 and xfs using fs_mark, a simple writeback test based on dd and a micro benchmark that does a streaming write to a large mapping (exercises use-once LRU logic) followed by streaming writes to a mix of anonymous and file-backed mappings. The command line for fs_mark when botted with 512M looked something like ./fs_mark -d /tmp/fsmark-2676 -D 100 -N 150 -n 150 -L 25 -t 1 -S0 -s 10485760 The number of files was adjusted depending on the amount of available memory so that the files created was about 3xRAM. For multiple threads, the -d switch is specified multiple times. The test machine is x86-64 with an older generation of AMD processor with 4 cores. The underlying storage was 4 disks configured as RAID-0 as this was the best configuration of storage I had available. Swap is on a separate disk. Dirty ratio was tuned to 40% instead of the default of 20%. Testing was run with and without monitors to both verify that the patches were operating as expected and that any performance gain was real and not due to interference from monitors. Here is a summary of results based on testing XFS. 512M1P-xfs Files/s mean 32.69 ( 0.00%) 34.44 ( 5.08%) 512M1P-xfs Elapsed Time fsmark 51.41 48.29 512M1P-xfs Elapsed Time simple-wb 114.09 108.61 512M1P-xfs Elapsed Time mmap-strm 113.46 109.34 512M1P-xfs Kswapd efficiency fsmark 62% 63% 512M1P-xfs Kswapd efficiency simple-wb 56% 61% 512M1P-xfs Kswapd efficiency mmap-strm 44% 42% 512M-xfs Files/s mean 30.78 ( 0.00%) 35.94 (14.36%) 512M-xfs Elapsed Time fsmark 56.08 48.90 512M-xfs Elapsed Time simple-wb 112.22 98.13 512M-xfs Elapsed Time mmap-strm 219.15 196.67 512M-xfs Kswapd efficiency fsmark 54% 56% 512M-xfs Kswapd efficiency simple-wb 54% 55% 512M-xfs Kswapd efficiency mmap-strm 45% 44% 512M-4X-xfs Files/s mean 30.31 ( 0.00%) 33.33 ( 9.06%) 512M-4X-xfs Elapsed Time fsmark 63.26 55.88 512M-4X-xfs Elapsed Time simple-wb 100.90 90.25 512M-4X-xfs Elapsed Time mmap-strm 261.73 255.38 512M-4X-xfs Kswapd efficiency fsmark 49% 50% 512M-4X-xfs Kswapd efficiency simple-wb 54% 56% 512M-4X-xfs Kswapd efficiency mmap-strm 37% 36% 512M-16X-xfs Files/s mean 60.89 ( 0.00%) 65.22 ( 6.64%) 512M-16X-xfs Elapsed Time fsmark 67.47 58.25 512M-16X-xfs Elapsed Time simple-wb 103.22 90.89 512M-16X-xfs Elapsed Time mmap-strm 237.09 198.82 512M-16X-xfs Kswapd efficiency fsmark 45% 46% 512M-16X-xfs Kswapd efficiency simple-wb 53% 55% 512M-16X-xfs Kswapd efficiency mmap-strm 33% 33% Up until 512-4X, the FSmark improvements were statistically significant. For the 4X and 16X tests the results were within standard deviations but just barely. The time to completion for all tests is improved which is an important result. In general, kswapd efficiency is not affected by skipping dirty pages. 1024M1P-xfs Files/s mean 39.09 ( 0.00%) 41.15 ( 5.01%) 1024M1P-xfs Elapsed Time fsmark 84.14 80.41 1024M1P-xfs Elapsed Time simple-wb 210.77 184.78 1024M1P-xfs Elapsed Time mmap-strm 162.00 160.34 1024M1P-xfs Kswapd efficiency fsmark 69% 75% 1024M1P-xfs Kswapd efficiency simple-wb 71% 77% 1024M1P-xfs Kswapd efficiency mmap-strm 43% 44% 1024M-xfs Files/s mean 35.45 ( 0.00%) 37.00 ( 4.19%) 1024M-xfs Elapsed Time fsmark 94.59 91.00 1024M-xfs Elapsed Time simple-wb 229.84 195.08 1024M-xfs Elapsed Time mmap-strm 405.38 440.29 1024M-xfs Kswapd efficiency fsmark 79% 71% 1024M-xfs Kswapd efficiency simple-wb 74% 74% 1024M-xfs Kswapd efficiency mmap-strm 39% 42% 1024M-4X-xfs Files/s mean 32.63 ( 0.00%) 35.05 ( 6.90%) 1024M-4X-xfs Elapsed Time fsmark 103.33 97.74 1024M-4X-xfs Elapsed Time simple-wb 204.48 178.57 1024M-4X-xfs Elapsed Time mmap-strm 528.38 511.88 1024M-4X-xfs Kswapd efficiency fsmark 81% 70% 1024M-4X-xfs Kswapd efficiency simple-wb 73% 72% 1024M-4X-xfs Kswapd efficiency mmap-strm 39% 38% 1024M-16X-xfs Files/s mean 42.65 ( 0.00%) 42.97 ( 0.74%) 1024M-16X-xfs Elapsed Time fsmark 103.11 99.11 1024M-16X-xfs Elapsed Time simple-wb 200.83 178.24 1024M-16X-xfs Elapsed Time mmap-strm 397.35 459.82 1024M-16X-xfs Kswapd efficiency fsmark 84% 69% 1024M-16X-xfs Kswapd efficiency simple-wb 74% 73% 1024M-16X-xfs Kswapd efficiency mmap-strm 39% 40% All FSMark tests up to 16X had statistically significant improvements. For the most part, tests are completing faster with the exception of the streaming writes to a mixture of anonymous and file-backed mappings which were slower in two cases In the cases where the mmap-strm tests were slower, there was more swapping due to dirty pages being skipped. The number of additional pages swapped is almost identical to the fewer number of pages written from reclaim. In other words, roughly the same number of pages were reclaimed but swapping was slower. As the test is a bit unrealistic and stresses memory heavily, the small shift is acceptable. 4608M1P-xfs Files/s mean 29.75 ( 0.00%) 30.96 ( 3.91%) 4608M1P-xfs Elapsed Time fsmark 512.01 492.15 4608M1P-xfs Elapsed Time simple-wb 618.18 566.24 4608M1P-xfs Elapsed Time mmap-strm 488.05 465.07 4608M1P-xfs Kswapd efficiency fsmark 93% 86% 4608M1P-xfs Kswapd efficiency simple-wb 88% 84% 4608M1P-xfs Kswapd efficiency mmap-strm 46% 45% 4608M-xfs Files/s mean 27.60 ( 0.00%) 28.85 ( 4.33%) 4608M-xfs Elapsed Time fsmark 555.96 532.34 4608M-xfs Elapsed Time simple-wb 659.72 571.85 4608M-xfs Elapsed Time mmap-strm 1082.57 1146.38 4608M-xfs Kswapd efficiency fsmark 89% 91% 4608M-xfs Kswapd efficiency simple-wb 88% 82% 4608M-xfs Kswapd efficiency mmap-strm 48% 46% 4608M-4X-xfs Files/s mean 26.00 ( 0.00%) 27.47 ( 5.35%) 4608M-4X-xfs Elapsed Time fsmark 592.91 564.00 4608M-4X-xfs Elapsed Time simple-wb 616.65 575.07 4608M-4X-xfs Elapsed Time mmap-strm 1773.02 1631.53 4608M-4X-xfs Kswapd efficiency fsmark 90% 94% 4608M-4X-xfs Kswapd efficiency simple-wb 87% 82% 4608M-4X-xfs Kswapd efficiency mmap-strm 43% 43% 4608M-16X-xfs Files/s mean 26.07 ( 0.00%) 26.42 ( 1.32%) 4608M-16X-xfs Elapsed Time fsmark 602.69 585.78 4608M-16X-xfs Elapsed Time simple-wb 606.60 573.81 4608M-16X-xfs Elapsed Time mmap-strm 1549.75 1441.86 4608M-16X-xfs Kswapd efficiency fsmark 98% 98% 4608M-16X-xfs Kswapd efficiency simple-wb 88% 82% 4608M-16X-xfs Kswapd efficiency mmap-strm 44% 42% Unlike the other tests, the fsmark results are not statistically significant but the min and max times are both improved and for the most part, tests completed faster. There are other indications that this is an improvement as well. For example, in the vast majority of cases, there were fewer pages scanned by direct reclaim implying in many cases that stalls due to direct reclaim are reduced. KSwapd is scanning more due to skipping dirty pages which is unfortunate but the CPU usage is still acceptable In an earlier set of tests, I used blktrace and in almost all cases throughput throughout the entire test was higher. However, I ended up discarding those results as recording blktrace data was too heavy for my liking. On a laptop, I plugged in a USB stick and ran a similar tests of tests using it as backing storage. A desktop environment was running and for the entire duration of the tests, firefox and gnome terminal were launching and exiting to vaguely simulate a user. 1024M-xfs Files/s mean 0.41 ( 0.00%) 0.44 ( 6.82%) 1024M-xfs Elapsed Time fsmark 2053.52 1641.03 1024M-xfs Elapsed Time simple-wb 1229.53 768.05 1024M-xfs Elapsed Time mmap-strm 4126.44 4597.03 1024M-xfs Kswapd efficiency fsmark 84% 85% 1024M-xfs Kswapd efficiency simple-wb 92% 81% 1024M-xfs Kswapd efficiency mmap-strm 60% 51% 1024M-xfs Avg wait ms fsmark 5404.53 4473.87 1024M-xfs Avg wait ms simple-wb 2541.35 1453.54 1024M-xfs Avg wait ms mmap-strm 3400.25 3852.53 The mmap-strm results were hurt because firefox launching had a tendency to push the test out of memory. On the postive side, firefox launched marginally faster with the patches applied. Time to completion for many tests was faster but more importantly - the "Avg wait" time as measured by iostat was far lower implying the system would be more responsive. It was also the case that "Avg wait ms" on the root filesystem was lower. I tested it manually and while the system felt slightly more responsive while copying data to a USB stick, it was marginal enough that it could be my imagination. This patch: do not writeback filesystem pages in direct reclaim. When kswapd is failing to keep zones above the min watermark, a process will enter direct reclaim in the same manner kswapd does. If a dirty page is encountered during the scan, this page is written to backing storage using mapping->writepage. This causes two problems. First, it can result in very deep call stacks, particularly if the target storage or filesystem are complex. Some filesystems ignore write requests from direct reclaim as a result. The second is that a single-page flush is inefficient in terms of IO. While there is an expectation that the elevator will merge requests, this does not always happen. Quoting Christoph Hellwig; The elevator has a relatively small window it can operate on, and can never fix up a bad large scale writeback pattern. This patch prevents direct reclaim writing back filesystem pages by checking if current is kswapd. Anonymous pages are still written to swap as there is not the equivalent of a flusher thread for anonymous pages. If the dirty pages cannot be written back, they are placed back on the LRU lists. There is now a direct dependency on dirty page balancing to prevent too many pages in the system being dirtied which would prevent reclaim making forward progress. Signed-off-by:
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Christoph Lameter authored
Add comments to explain the page statistics field in the mm_struct. [akpm@linux-foundation.org: add missing ;] Signed-off-by:
Christoph Lameter <cl@linux.com> Signed-off-by:
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Christoph Lameter authored
Some kernel components pin user space memory (infiniband and perf) (by increasing the page count) and account that memory as "mlocked". The difference between mlocking and pinning is: A. mlocked pages are marked with PG_mlocked and are exempt from swapping. Page migration may move them around though. They are kept on a special LRU list. B. Pinned pages cannot be moved because something needs to directly access physical memory. They may not be on any LRU list. I recently saw an mlockalled process where mm->locked_vm became bigger than the virtual size of the process (!) because some memory was accounted for twice: Once when the page was mlocked and once when the Infiniband layer increased the refcount because it needt to pin the RDMA memory. This patch introduces a separate counter for pinned pages and accounts them seperately. Signed-off-by:
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