- 20 May, 2016 40 commits
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Mel Gorman authored
Every page allocated checks a number of page fields for validity. This catches corruption bugs of pages that are already freed but it is expensive. This patch weakens the debugging check by checking PCP pages only when the PCP lists are being refilled. All compound pages are checked. This potentially avoids debugging checks entirely if the PCP lists are never emptied and refilled so some corruption issues may be missed. Full checking requires DEBUG_VM. With the two deferred debugging patches applied, the impact to a page allocator microbenchmark is 4.6.0-rc3 4.6.0-rc3 inline-v3r6 deferalloc-v3r7 Min alloc-odr0-1 344.00 ( 0.00%) 317.00 ( 7.85%) Min alloc-odr0-2 248.00 ( 0.00%) 231.00 ( 6.85%) Min alloc-odr0-4 209.00 ( 0.00%) 192.00 ( 8.13%) Min alloc-odr0-8 181.00 ( 0.00%) 166.00 ( 8.29%) Min alloc-odr0-16 168.00 ( 0.00%) 154.00 ( 8.33%) Min alloc-odr0-32 161.00 ( 0.00%) 148.00 ( 8.07%) Min alloc-odr0-64 158.00 ( 0.00%) 145.00 ( 8.23%) Min alloc-odr0-128 156.00 ( 0.00%) 143.00 ( 8.33%) Min alloc-odr0-256 168.00 ( 0.00%) 154.00 ( 8.33%) Min alloc-odr0-512 178.00 ( 0.00%) 167.00 ( 6.18%) Min alloc-odr0-1024 186.00 ( 0.00%) 174.00 ( 6.45%) Min alloc-odr0-2048 192.00 ( 0.00%) 180.00 ( 6.25%) Min alloc-odr0-4096 198.00 ( 0.00%) 184.00 ( 7.07%) Min alloc-odr0-8192 200.00 ( 0.00%) 188.00 ( 6.00%) Min alloc-odr0-16384 201.00 ( 0.00%) 188.00 ( 6.47%) Min free-odr0-1 189.00 ( 0.00%) 180.00 ( 4.76%) Min free-odr0-2 132.00 ( 0.00%) 126.00 ( 4.55%) Min free-odr0-4 104.00 ( 0.00%) 99.00 ( 4.81%) Min free-odr0-8 90.00 ( 0.00%) 85.00 ( 5.56%) Min free-odr0-16 84.00 ( 0.00%) 80.00 ( 4.76%) Min free-odr0-32 80.00 ( 0.00%) 76.00 ( 5.00%) Min free-odr0-64 78.00 ( 0.00%) 74.00 ( 5.13%) Min free-odr0-128 77.00 ( 0.00%) 73.00 ( 5.19%) Min free-odr0-256 94.00 ( 0.00%) 91.00 ( 3.19%) Min free-odr0-512 108.00 ( 0.00%) 112.00 ( -3.70%) Min free-odr0-1024 115.00 ( 0.00%) 118.00 ( -2.61%) Min free-odr0-2048 120.00 ( 0.00%) 125.00 ( -4.17%) Min free-odr0-4096 123.00 ( 0.00%) 129.00 ( -4.88%) Min free-odr0-8192 126.00 ( 0.00%) 130.00 ( -3.17%) Min free-odr0-16384 126.00 ( 0.00%) 131.00 ( -3.97%) Note that the free paths for large numbers of pages is impacted as the debugging cost gets shifted into that path when the page data is no longer necessarily cache-hot. Signed-off-by:Mel Gorman <mgorman@techsingularity.net> Acked-by:
Vlastimil Babka <vbabka@suse.cz> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Mel Gorman authored
Every page free checks a number of page fields for validity. This catches premature frees and corruptions but it is also expensive. This patch weakens the debugging check by checking PCP pages at the time they are drained from the PCP list. This will trigger the bug but the site that freed the corrupt page will be lost. To get the full context, a kernel rebuild with DEBUG_VM is necessary. [akpm@linux-foundation.org: fix build] Signed-off-by:
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Vlastimil Babka authored
An important function for cpusets is cpuset_node_allowed(), which optimizes on the fact if there's a single root CPU set, it must be trivially allowed. But the check "nr_cpusets() <= 1" doesn't use the cpusets_enabled_key static key the right way where static keys eliminate branching overhead with jump labels. This patch converts it so that static key is used properly. It's also switched to the new static key API and the checking functions are converted to return bool instead of int. We also provide a new variant __cpuset_zone_allowed() which expects that the static key check was already done and they key was enabled. This is needed for get_page_from_freelist() where we want to also avoid the relatively slower check when ALLOC_CPUSET is not set in alloc_flags. The impact on the page allocator microbenchmark is less than expected but the cleanup in itself is worthwhile. 4.6.0-rc2 4.6.0-rc2 multcheck-v1r20 cpuset-v1r20 Min alloc-odr0-1 348.00 ( 0.00%) 348.00 ( 0.00%) Min alloc-odr0-2 254.00 ( 0.00%) 254.00 ( 0.00%) Min alloc-odr0-4 213.00 ( 0.00%) 213.00 ( 0.00%) Min alloc-odr0-8 186.00 ( 0.00%) 183.00 ( 1.61%) Min alloc-odr0-16 173.00 ( 0.00%) 171.00 ( 1.16%) Min alloc-odr0-32 166.00 ( 0.00%) 163.00 ( 1.81%) Min alloc-odr0-64 162.00 ( 0.00%) 159.00 ( 1.85%) Min alloc-odr0-128 160.00 ( 0.00%) 157.00 ( 1.88%) Min alloc-odr0-256 169.00 ( 0.00%) 166.00 ( 1.78%) Min alloc-odr0-512 180.00 ( 0.00%) 180.00 ( 0.00%) Min alloc-odr0-1024 188.00 ( 0.00%) 187.00 ( 0.53%) Min alloc-odr0-2048 194.00 ( 0.00%) 193.00 ( 0.52%) Min alloc-odr0-4096 199.00 ( 0.00%) 198.00 ( 0.50%) Min alloc-odr0-8192 202.00 ( 0.00%) 201.00 ( 0.50%) Min alloc-odr0-16384 203.00 ( 0.00%) 202.00 ( 0.49%) Signed-off-by:Zefan Li <lizefan@huawei.com> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by:
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Mel Gorman authored
The function call overhead of get_pfnblock_flags_mask() is measurable in the page free paths. This patch uses an inlined version that is faster. Signed-off-by:
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Mel Gorman authored
The original count is never reused so it can be removed. Signed-off-by:
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Mel Gorman authored
Check without side-effects should be easier to maintain. It also removes the duplicated cpupid and flags reset done in !DEBUG_VM variant of both free_pcp_prepare() and then bulkfree_pcp_prepare(). Finally, it enables the next patch. It shouldn't result in new branches, thanks to inlining of the check. !DEBUG_VM bloat-o-meter: add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-27 (-27) function old new delta __free_pages_ok 748 739 -9 free_pcppages_bulk 1403 1385 -18 DEBUG_VM: add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-28 (-28) function old new delta free_pages_prepare 806 778 -28 This is also slightly faster because cpupid information is not set on tail pages so we can avoid resets there. Signed-off-by:
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Mel Gorman authored
From: Vlastimil Babka <vbabka@suse.cz> !DEBUG_VM size and bloat-o-meter: add/remove: 1/0 grow/shrink: 0/2 up/down: 124/-370 (-246) function old new delta free_pages_check_bad - 124 +124 free_pcppages_bulk 1288 1171 -117 __free_pages_ok 948 695 -253 DEBUG_VM: add/remove: 1/0 grow/shrink: 0/1 up/down: 124/-214 (-90) function old new delta free_pages_check_bad - 124 +124 free_pages_prepare 1112 898 -214 [akpm@linux-foundation.org: fix whitespace] Signed-off-by:
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Mel Gorman authored
Every page allocated or freed is checked for sanity to avoid corruptions that are difficult to detect later. A bad page could be due to a number of fields. Instead of using multiple branches, this patch combines multiple fields into a single branch. A detailed check is only necessary if that check fails. 4.6.0-rc2 4.6.0-rc2 initonce-v1r20 multcheck-v1r20 Min alloc-odr0-1 359.00 ( 0.00%) 348.00 ( 3.06%) Min alloc-odr0-2 260.00 ( 0.00%) 254.00 ( 2.31%) Min alloc-odr0-4 214.00 ( 0.00%) 213.00 ( 0.47%) Min alloc-odr0-8 186.00 ( 0.00%) 186.00 ( 0.00%) Min alloc-odr0-16 173.00 ( 0.00%) 173.00 ( 0.00%) Min alloc-odr0-32 165.00 ( 0.00%) 166.00 ( -0.61%) Min alloc-odr0-64 162.00 ( 0.00%) 162.00 ( 0.00%) Min alloc-odr0-128 161.00 ( 0.00%) 160.00 ( 0.62%) Min alloc-odr0-256 170.00 ( 0.00%) 169.00 ( 0.59%) Min alloc-odr0-512 181.00 ( 0.00%) 180.00 ( 0.55%) Min alloc-odr0-1024 190.00 ( 0.00%) 188.00 ( 1.05%) Min alloc-odr0-2048 196.00 ( 0.00%) 194.00 ( 1.02%) Min alloc-odr0-4096 202.00 ( 0.00%) 199.00 ( 1.49%) Min alloc-odr0-8192 205.00 ( 0.00%) 202.00 ( 1.46%) Min alloc-odr0-16384 205.00 ( 0.00%) 203.00 ( 0.98%) Again, the benefit is marginal but avoiding excessive branches is important. Ideally the paths would not have to check these conditions at all but regrettably abandoning the tests would make use-after-free bugs much harder to detect. Signed-off-by: -
Mel Gorman authored
The classzone_idx can be inferred from preferred_zoneref so remove the unnecessary field and save stack space. Signed-off-by:
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Mel Gorman authored
The allocator fast path looks up the first usable zone in a zonelist and then get_page_from_freelist does the same job in the zonelist iterator. This patch preserves the necessary information. 4.6.0-rc2 4.6.0-rc2 fastmark-v1r20 initonce-v1r20 Min alloc-odr0-1 364.00 ( 0.00%) 359.00 ( 1.37%) Min alloc-odr0-2 262.00 ( 0.00%) 260.00 ( 0.76%) Min alloc-odr0-4 214.00 ( 0.00%) 214.00 ( 0.00%) Min alloc-odr0-8 186.00 ( 0.00%) 186.00 ( 0.00%) Min alloc-odr0-16 173.00 ( 0.00%) 173.00 ( 0.00%) Min alloc-odr0-32 165.00 ( 0.00%) 165.00 ( 0.00%) Min alloc-odr0-64 161.00 ( 0.00%) 162.00 ( -0.62%) Min alloc-odr0-128 159.00 ( 0.00%) 161.00 ( -1.26%) Min alloc-odr0-256 168.00 ( 0.00%) 170.00 ( -1.19%) Min alloc-odr0-512 180.00 ( 0.00%) 181.00 ( -0.56%) Min alloc-odr0-1024 190.00 ( 0.00%) 190.00 ( 0.00%) Min alloc-odr0-2048 196.00 ( 0.00%) 196.00 ( 0.00%) Min alloc-odr0-4096 202.00 ( 0.00%) 202.00 ( 0.00%) Min alloc-odr0-8192 206.00 ( 0.00%) 205.00 ( 0.49%) Min alloc-odr0-16384 206.00 ( 0.00%) 205.00 ( 0.49%) The benefit is negligible and the results are within the noise but each cycle counts. Signed-off-by: -
Mel Gorman authored
Watermarks have to be checked on every allocation including the number of pages being allocated and whether reserves can be accessed. The reserves only matter if memory is limited and the free_pages adjustment only applies to high-order pages. This patch adds a shortcut for order-0 pages that avoids numerous calculations if there is plenty of free memory yielding the following performance difference in a page allocator microbenchmark; 4.6.0-rc2 4.6.0-rc2 optfair-v1r20 fastmark-v1r20 Min alloc-odr0-1 380.00 ( 0.00%) 364.00 ( 4.21%) Min alloc-odr0-2 273.00 ( 0.00%) 262.00 ( 4.03%) Min alloc-odr0-4 227.00 ( 0.00%) 214.00 ( 5.73%) Min alloc-odr0-8 196.00 ( 0.00%) 186.00 ( 5.10%) Min alloc-odr0-16 183.00 ( 0.00%) 173.00 ( 5.46%) Min alloc-odr0-32 173.00 ( 0.00%) 165.00 ( 4.62%) Min alloc-odr0-64 169.00 ( 0.00%) 161.00 ( 4.73%) Min alloc-odr0-128 169.00 ( 0.00%) 159.00 ( 5.92%) Min alloc-odr0-256 180.00 ( 0.00%) 168.00 ( 6.67%) Min alloc-odr0-512 190.00 ( 0.00%) 180.00 ( 5.26%) Min alloc-odr0-1024 198.00 ( 0.00%) 190.00 ( 4.04%) Min alloc-odr0-2048 204.00 ( 0.00%) 196.00 ( 3.92%) Min alloc-odr0-4096 209.00 ( 0.00%) 202.00 ( 3.35%) Min alloc-odr0-8192 213.00 ( 0.00%) 206.00 ( 3.29%) Min alloc-odr0-16384 214.00 ( 0.00%) 206.00 ( 3.74%) Signed-off-by: -
Mel Gorman authored
The fair zone allocation policy is not without cost but it can be reduced slightly. This patch removes an unnecessary local variable, checks the likely conditions of the fair zone policy first, uses a bool instead of a flags check and falls through when a remote node is encountered instead of doing a full restart. The benefit is marginal but it's there 4.6.0-rc2 4.6.0-rc2 decstat-v1r20 optfair-v1r20 Min alloc-odr0-1 377.00 ( 0.00%) 380.00 ( -0.80%) Min alloc-odr0-2 273.00 ( 0.00%) 273.00 ( 0.00%) Min alloc-odr0-4 226.00 ( 0.00%) 227.00 ( -0.44%) Min alloc-odr0-8 196.00 ( 0.00%) 196.00 ( 0.00%) Min alloc-odr0-16 183.00 ( 0.00%) 183.00 ( 0.00%) Min alloc-odr0-32 175.00 ( 0.00%) 173.00 ( 1.14%) Min alloc-odr0-64 172.00 ( 0.00%) 169.00 ( 1.74%) Min alloc-odr0-128 170.00 ( 0.00%) 169.00 ( 0.59%) Min alloc-odr0-256 183.00 ( 0.00%) 180.00 ( 1.64%) Min alloc-odr0-512 191.00 ( 0.00%) 190.00 ( 0.52%) Min alloc-odr0-1024 199.00 ( 0.00%) 198.00 ( 0.50%) Min alloc-odr0-2048 204.00 ( 0.00%) 204.00 ( 0.00%) Min alloc-odr0-4096 210.00 ( 0.00%) 209.00 ( 0.48%) Min alloc-odr0-8192 213.00 ( 0.00%) 213.00 ( 0.00%) Min alloc-odr0-16384 214.00 ( 0.00%) 214.00 ( 0.00%) The benefit is marginal at best but one of the most important benefits, avoiding a second search when falling back to another node is not triggered by this particular test so the benefit for some corner cases is understated. Signed-off-by: -
Mel Gorman authored
The page allocator fast path checks page multiple times unnecessarily. This patch avoids all the slowpath checks if the first allocation attempt succeeds. Signed-off-by:
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Mel Gorman authored
When bulk freeing pages from the per-cpu lists the zone is checked for isolated pageblocks on every release. This patch checks it once per drain. [mgorman@techsingularity.net: fix locking radce, per Vlastimil] Signed-off-by:
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Mel Gorman authored
__GFP_HARDWALL only has meaning in the context of cpusets but the fast path always applies the flag on the first attempt. Move the manipulations into the cpuset paths where they will be masked by a static branch in the common case. With the other micro-optimisations in this series combined, the impact on a page allocator microbenchmark is 4.6.0-rc2 4.6.0-rc2 decstat-v1r20 micro-v1r20 Min alloc-odr0-1 381.00 ( 0.00%) 377.00 ( 1.05%) Min alloc-odr0-2 275.00 ( 0.00%) 273.00 ( 0.73%) Min alloc-odr0-4 229.00 ( 0.00%) 226.00 ( 1.31%) Min alloc-odr0-8 199.00 ( 0.00%) 196.00 ( 1.51%) Min alloc-odr0-16 186.00 ( 0.00%) 183.00 ( 1.61%) Min alloc-odr0-32 179.00 ( 0.00%) 175.00 ( 2.23%) Min alloc-odr0-64 174.00 ( 0.00%) 172.00 ( 1.15%) Min alloc-odr0-128 172.00 ( 0.00%) 170.00 ( 1.16%) Min alloc-odr0-256 181.00 ( 0.00%) 183.00 ( -1.10%) Min alloc-odr0-512 193.00 ( 0.00%) 191.00 ( 1.04%) Min alloc-odr0-1024 201.00 ( 0.00%) 199.00 ( 1.00%) Min alloc-odr0-2048 206.00 ( 0.00%) 204.00 ( 0.97%) Min alloc-odr0-4096 212.00 ( 0.00%) 210.00 ( 0.94%) Min alloc-odr0-8192 215.00 ( 0.00%) 213.00 ( 0.93%) Min alloc-odr0-16384 216.00 ( 0.00%) 214.00 ( 0.93%) Signed-off-by: -
Mel Gorman authored
The current reset unnecessarily clears flags and makes pointless calculations. Signed-off-by:
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Mel Gorman authored
page is guaranteed to be set before it is read with or without the initialisation. [akpm@linux-foundation.org: fix warning] Signed-off-by:
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Mel Gorman authored
Signed-off-by:
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Mel Gorman authored
zonelist here is a copy of a struct field that is used once. Ditch it. Signed-off-by:
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Mel Gorman authored
The number of zones skipped to a zone expiring its fair zone allocation quota is irrelevant. Convert to bool. Signed-off-by:
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Mel Gorman authored
alloc_flags is a bitmask of flags but it is signed which does not necessarily generate the best code depending on the compiler. Even without an impact, it makes more sense that this be unsigned. Signed-off-by:
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Mel Gorman authored
Pageblocks have an associated bitmap to store migrate types and whether the pageblock should be skipped during compaction. The bitmap may be associated with a memory section or a zone but the zone is looked up unconditionally. The compiler should optimise this away automatically so this is a cosmetic patch only in many cases. Signed-off-by:
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Mel Gorman authored
__dec_zone_state is cheaper to use for removing an order-0 page as it has fewer conditions to check. The performance difference on a page allocator microbenchmark is; 4.6.0-rc2 4.6.0-rc2 optiter-v1r20 decstat-v1r20 Min alloc-odr0-1 382.00 ( 0.00%) 381.00 ( 0.26%) Min alloc-odr0-2 282.00 ( 0.00%) 275.00 ( 2.48%) Min alloc-odr0-4 233.00 ( 0.00%) 229.00 ( 1.72%) Min alloc-odr0-8 203.00 ( 0.00%) 199.00 ( 1.97%) Min alloc-odr0-16 188.00 ( 0.00%) 186.00 ( 1.06%) Min alloc-odr0-32 182.00 ( 0.00%) 179.00 ( 1.65%) Min alloc-odr0-64 177.00 ( 0.00%) 174.00 ( 1.69%) Min alloc-odr0-128 175.00 ( 0.00%) 172.00 ( 1.71%) Min alloc-odr0-256 184.00 ( 0.00%) 181.00 ( 1.63%) Min alloc-odr0-512 197.00 ( 0.00%) 193.00 ( 2.03%) Min alloc-odr0-1024 203.00 ( 0.00%) 201.00 ( 0.99%) Min alloc-odr0-2048 209.00 ( 0.00%) 206.00 ( 1.44%) Min alloc-odr0-4096 214.00 ( 0.00%) 212.00 ( 0.93%) Min alloc-odr0-8192 218.00 ( 0.00%) 215.00 ( 1.38%) Min alloc-odr0-16384 219.00 ( 0.00%) 216.00 ( 1.37%) Signed-off-by: -
Mel Gorman authored
The page allocator iterates through a zonelist for zones that match the addressing limitations and nodemask of the caller but many allocations will not be restricted. Despite this, there is always functional call overhead which builds up. This patch inlines the optimistic basic case and only calls the iterator function for the complex case. A hindrance was the fact that cpuset_current_mems_allowed is used in the fastpath as the allowed nodemask even though all nodes are allowed on most systems. The patch handles this by only considering cpuset_current_mems_allowed if a cpuset exists. As well as being faster in the fast-path, this removes some junk in the slowpath. The performance difference on a page allocator microbenchmark is; 4.6.0-rc2 4.6.0-rc2 statinline-v1r20 optiter-v1r20 Min alloc-odr0-1 412.00 ( 0.00%) 382.00 ( 7.28%) Min alloc-odr0-2 301.00 ( 0.00%) 282.00 ( 6.31%) Min alloc-odr0-4 247.00 ( 0.00%) 233.00 ( 5.67%) Min alloc-odr0-8 215.00 ( 0.00%) 203.00 ( 5.58%) Min alloc-odr0-16 199.00 ( 0.00%) 188.00 ( 5.53%) Min alloc-odr0-32 191.00 ( 0.00%) 182.00 ( 4.71%) Min alloc-odr0-64 187.00 ( 0.00%) 177.00 ( 5.35%) Min alloc-odr0-128 185.00 ( 0.00%) 175.00 ( 5.41%) Min alloc-odr0-256 193.00 ( 0.00%) 184.00 ( 4.66%) Min alloc-odr0-512 207.00 ( 0.00%) 197.00 ( 4.83%) Min alloc-odr0-1024 213.00 ( 0.00%) 203.00 ( 4.69%) Min alloc-odr0-2048 220.00 ( 0.00%) 209.00 ( 5.00%) Min alloc-odr0-4096 226.00 ( 0.00%) 214.00 ( 5.31%) Min alloc-odr0-8192 229.00 ( 0.00%) 218.00 ( 4.80%) Min alloc-odr0-16384 229.00 ( 0.00%) 219.00 ( 4.37%) perf indicated that next_zones_zonelist disappeared in the profile and __next_zones_zonelist did not appear. This is expected as the micro-benchmark would hit the inlined fast-path every time. Signed-off-by: -
Mel Gorman authored
zone_statistics has one call-site but it's a public function. Make it static and inline. The performance difference on a page allocator microbenchmark is; 4.6.0-rc2 4.6.0-rc2 statbranch-v1r20 statinline-v1r20 Min alloc-odr0-1 419.00 ( 0.00%) 412.00 ( 1.67%) Min alloc-odr0-2 305.00 ( 0.00%) 301.00 ( 1.31%) Min alloc-odr0-4 250.00 ( 0.00%) 247.00 ( 1.20%) Min alloc-odr0-8 219.00 ( 0.00%) 215.00 ( 1.83%) Min alloc-odr0-16 203.00 ( 0.00%) 199.00 ( 1.97%) Min alloc-odr0-32 195.00 ( 0.00%) 191.00 ( 2.05%) Min alloc-odr0-64 191.00 ( 0.00%) 187.00 ( 2.09%) Min alloc-odr0-128 189.00 ( 0.00%) 185.00 ( 2.12%) Min alloc-odr0-256 198.00 ( 0.00%) 193.00 ( 2.53%) Min alloc-odr0-512 210.00 ( 0.00%) 207.00 ( 1.43%) Min alloc-odr0-1024 216.00 ( 0.00%) 213.00 ( 1.39%) Min alloc-odr0-2048 221.00 ( 0.00%) 220.00 ( 0.45%) Min alloc-odr0-4096 227.00 ( 0.00%) 226.00 ( 0.44%) Min alloc-odr0-8192 232.00 ( 0.00%) 229.00 ( 1.29%) Min alloc-odr0-16384 232.00 ( 0.00%) 229.00 ( 1.29%) Signed-off-by: -
Mel Gorman authored
zone_statistics has more branches than it really needs to take an unlikely GFP flag into account. Reduce the number and annotate the unlikely flag. The performance difference on a page allocator microbenchmark is; 4.6.0-rc2 4.6.0-rc2 nocompound-v1r10 statbranch-v1r10 Min alloc-odr0-1 417.00 ( 0.00%) 419.00 ( -0.48%) Min alloc-odr0-2 308.00 ( 0.00%) 305.00 ( 0.97%) Min alloc-odr0-4 253.00 ( 0.00%) 250.00 ( 1.19%) Min alloc-odr0-8 221.00 ( 0.00%) 219.00 ( 0.90%) Min alloc-odr0-16 205.00 ( 0.00%) 203.00 ( 0.98%) Min alloc-odr0-32 199.00 ( 0.00%) 195.00 ( 2.01%) Min alloc-odr0-64 193.00 ( 0.00%) 191.00 ( 1.04%) Min alloc-odr0-128 191.00 ( 0.00%) 189.00 ( 1.05%) Min alloc-odr0-256 200.00 ( 0.00%) 198.00 ( 1.00%) Min alloc-odr0-512 212.00 ( 0.00%) 210.00 ( 0.94%) Min alloc-odr0-1024 219.00 ( 0.00%) 216.00 ( 1.37%) Min alloc-odr0-2048 225.00 ( 0.00%) 221.00 ( 1.78%) Min alloc-odr0-4096 231.00 ( 0.00%) 227.00 ( 1.73%) Min alloc-odr0-8192 234.00 ( 0.00%) 232.00 ( 0.85%) Min alloc-odr0-16384 234.00 ( 0.00%) 232.00 ( 0.85%) Signed-off-by: -
Mel Gorman authored
The PageAnon check always checks for compound_head but this is a relatively expensive check if the caller already knows the page is a head page. This patch creates a helper and uses it in the page free path which only operates on head pages. With this patch and "Only check PageCompound for high-order pages", the performance difference on a page allocator microbenchmark is; 4.6.0-rc2 4.6.0-rc2 vanilla nocompound-v1r20 Min alloc-odr0-1 425.00 ( 0.00%) 417.00 ( 1.88%) Min alloc-odr0-2 313.00 ( 0.00%) 308.00 ( 1.60%) Min alloc-odr0-4 257.00 ( 0.00%) 253.00 ( 1.56%) Min alloc-odr0-8 224.00 ( 0.00%) 221.00 ( 1.34%) Min alloc-odr0-16 208.00 ( 0.00%) 205.00 ( 1.44%) Min alloc-odr0-32 199.00 ( 0.00%) 199.00 ( 0.00%) Min alloc-odr0-64 195.00 ( 0.00%) 193.00 ( 1.03%) Min alloc-odr0-128 192.00 ( 0.00%) 191.00 ( 0.52%) Min alloc-odr0-256 204.00 ( 0.00%) 200.00 ( 1.96%) Min alloc-odr0-512 213.00 ( 0.00%) 212.00 ( 0.47%) Min alloc-odr0-1024 219.00 ( 0.00%) 219.00 ( 0.00%) Min alloc-odr0-2048 225.00 ( 0.00%) 225.00 ( 0.00%) Min alloc-odr0-4096 230.00 ( 0.00%) 231.00 ( -0.43%) Min alloc-odr0-8192 235.00 ( 0.00%) 234.00 ( 0.43%) Min alloc-odr0-16384 235.00 ( 0.00%) 234.00 ( 0.43%) Min free-odr0-1 215.00 ( 0.00%) 191.00 ( 11.16%) Min free-odr0-2 152.00 ( 0.00%) 136.00 ( 10.53%) Min free-odr0-4 119.00 ( 0.00%) 107.00 ( 10.08%) Min free-odr0-8 106.00 ( 0.00%) 96.00 ( 9.43%) Min free-odr0-16 97.00 ( 0.00%) 87.00 ( 10.31%) Min free-odr0-32 91.00 ( 0.00%) 83.00 ( 8.79%) Min free-odr0-64 89.00 ( 0.00%) 81.00 ( 8.99%) Min free-odr0-128 88.00 ( 0.00%) 80.00 ( 9.09%) Min free-odr0-256 106.00 ( 0.00%) 95.00 ( 10.38%) Min free-odr0-512 116.00 ( 0.00%) 111.00 ( 4.31%) Min free-odr0-1024 125.00 ( 0.00%) 118.00 ( 5.60%) Min free-odr0-2048 133.00 ( 0.00%) 126.00 ( 5.26%) Min free-odr0-4096 136.00 ( 0.00%) 130.00 ( 4.41%) Min free-odr0-8192 138.00 ( 0.00%) 130.00 ( 5.80%) Min free-odr0-16384 137.00 ( 0.00%) 130.00 ( 5.11%) There is a sizable boost to the free allocator performance. While there is an apparent boost on the allocation side, it's likely a co-incidence or due to the patches slightly reducing cache footprint. Signed-off-by: -
Mel Gorman authored
Another year, another round of page allocator optimisations focusing this time on the alloc and free fast paths. This should be of help to workloads that are allocator-intensive from kernel space where the cost of zeroing is not nceessraily incurred. The series is motivated by the observation that page alloc microbenchmarks on multiple machines regressed between 3.12.44 and 4.4. Second, there is discussions before LSF/MM considering the possibility of adding another page allocator which is potentially hazardous but a patch series improving performance is better than whining. After the series is applied, there are still hazards. In the free paths, the debugging checking and page zone/pageblock lookups dominate but there was not an obvious solution to that. In the alloc path, the major contributers are dealing with zonelists, new page preperation, the fair zone allocation and numerous statistic updates. The fair zone allocator is removed by the per-node LRU series if that gets merged so it's nor a major concern at the moment. On normal userspace benchmarks, there is little impact as the zeroing cost is significant but it's visible aim9 4.6.0-rc3 4.6.0-rc3 vanilla deferalloc-v3 Min page_test 828693.33 ( 0.00%) 887060.00 ( 7.04%) Min brk_test 4847266.67 ( 0.00%) 4966266.67 ( 2.45%) Min exec_test 1271.00 ( 0.00%) 1275.67 ( 0.37%) Min fork_test 12371.75 ( 0.00%) 12380.00 ( 0.07%) The overall impact on a page allocator microbenchmark for a range of orders and number of pages allocated in a batch is 4.6.0-rc3 4.6.0-rc3 vanilla deferalloc-v3r7 Min alloc-odr0-1 428.00 ( 0.00%) 316.00 ( 26.17%) Min alloc-odr0-2 314.00 ( 0.00%) 231.00 ( 26.43%) Min alloc-odr0-4 256.00 ( 0.00%) 192.00 ( 25.00%) Min alloc-odr0-8 222.00 ( 0.00%) 166.00 ( 25.23%) Min alloc-odr0-16 207.00 ( 0.00%) 154.00 ( 25.60%) Min alloc-odr0-32 197.00 ( 0.00%) 148.00 ( 24.87%) Min alloc-odr0-64 193.00 ( 0.00%) 144.00 ( 25.39%) Min alloc-odr0-128 191.00 ( 0.00%) 143.00 ( 25.13%) Min alloc-odr0-256 203.00 ( 0.00%) 153.00 ( 24.63%) Min alloc-odr0-512 212.00 ( 0.00%) 165.00 ( 22.17%) Min alloc-odr0-1024 221.00 ( 0.00%) 172.00 ( 22.17%) Min alloc-odr0-2048 225.00 ( 0.00%) 179.00 ( 20.44%) Min alloc-odr0-4096 232.00 ( 0.00%) 185.00 ( 20.26%) Min alloc-odr0-8192 235.00 ( 0.00%) 187.00 ( 20.43%) Min alloc-odr0-16384 236.00 ( 0.00%) 188.00 ( 20.34%) Min alloc-odr1-1 519.00 ( 0.00%) 450.00 ( 13.29%) Min alloc-odr1-2 391.00 ( 0.00%) 336.00 ( 14.07%) Min alloc-odr1-4 313.00 ( 0.00%) 268.00 ( 14.38%) Min alloc-odr1-8 277.00 ( 0.00%) 235.00 ( 15.16%) Min alloc-odr1-16 256.00 ( 0.00%) 218.00 ( 14.84%) Min alloc-odr1-32 252.00 ( 0.00%) 212.00 ( 15.87%) Min alloc-odr1-64 244.00 ( 0.00%) 206.00 ( 15.57%) Min alloc-odr1-128 244.00 ( 0.00%) 207.00 ( 15.16%) Min alloc-odr1-256 243.00 ( 0.00%) 207.00 ( 14.81%) Min alloc-odr1-512 245.00 ( 0.00%) 209.00 ( 14.69%) Min alloc-odr1-1024 248.00 ( 0.00%) 214.00 ( 13.71%) Min alloc-odr1-2048 253.00 ( 0.00%) 220.00 ( 13.04%) Min alloc-odr1-4096 258.00 ( 0.00%) 224.00 ( 13.18%) Min alloc-odr1-8192 261.00 ( 0.00%) 229.00 ( 12.26%) Min alloc-odr2-1 560.00 ( 0.00%) 753.00 (-34.46%) Min alloc-odr2-2 424.00 ( 0.00%) 351.00 ( 17.22%) Min alloc-odr2-4 339.00 ( 0.00%) 393.00 (-15.93%) Min alloc-odr2-8 298.00 ( 0.00%) 246.00 ( 17.45%) Min alloc-odr2-16 276.00 ( 0.00%) 227.00 ( 17.75%) Min alloc-odr2-32 271.00 ( 0.00%) 221.00 ( 18.45%) Min alloc-odr2-64 264.00 ( 0.00%) 217.00 ( 17.80%) Min alloc-odr2-128 264.00 ( 0.00%) 217.00 ( 17.80%) Min alloc-odr2-256 264.00 ( 0.00%) 218.00 ( 17.42%) Min alloc-odr2-512 269.00 ( 0.00%) 223.00 ( 17.10%) Min alloc-odr2-1024 279.00 ( 0.00%) 230.00 ( 17.56%) Min alloc-odr2-2048 283.00 ( 0.00%) 235.00 ( 16.96%) Min alloc-odr2-4096 285.00 ( 0.00%) 239.00 ( 16.14%) Min alloc-odr3-1 629.00 ( 0.00%) 505.00 ( 19.71%) Min alloc-odr3-2 472.00 ( 0.00%) 374.00 ( 20.76%) Min alloc-odr3-4 383.00 ( 0.00%) 301.00 ( 21.41%) Min alloc-odr3-8 341.00 ( 0.00%) 266.00 ( 21.99%) Min alloc-odr3-16 316.00 ( 0.00%) 248.00 ( 21.52%) Min alloc-odr3-32 308.00 ( 0.00%) 241.00 ( 21.75%) Min alloc-odr3-64 305.00 ( 0.00%) 241.00 ( 20.98%) Min alloc-odr3-128 308.00 ( 0.00%) 244.00 ( 20.78%) Min alloc-odr3-256 317.00 ( 0.00%) 249.00 ( 21.45%) Min alloc-odr3-512 327.00 ( 0.00%) 256.00 ( 21.71%) Min alloc-odr3-1024 331.00 ( 0.00%) 261.00 ( 21.15%) Min alloc-odr3-2048 333.00 ( 0.00%) 266.00 ( 20.12%) Min alloc-odr4-1 767.00 ( 0.00%) 572.00 ( 25.42%) Min alloc-odr4-2 578.00 ( 0.00%) 429.00 ( 25.78%) Min alloc-odr4-4 474.00 ( 0.00%) 346.00 ( 27.00%) Min alloc-odr4-8 422.00 ( 0.00%) 310.00 ( 26.54%) Min alloc-odr4-16 399.00 ( 0.00%) 295.00 ( 26.07%) Min alloc-odr4-32 392.00 ( 0.00%) 293.00 ( 25.26%) Min alloc-odr4-64 394.00 ( 0.00%) 293.00 ( 25.63%) Min alloc-odr4-128 405.00 ( 0.00%) 305.00 ( 24.69%) Min alloc-odr4-256 417.00 ( 0.00%) 319.00 ( 23.50%) Min alloc-odr4-512 425.00 ( 0.00%) 326.00 ( 23.29%) Min alloc-odr4-1024 426.00 ( 0.00%) 329.00 ( 22.77%) Min free-odr0-1 216.00 ( 0.00%) 178.00 ( 17.59%) Min free-odr0-2 152.00 ( 0.00%) 125.00 ( 17.76%) Min free-odr0-4 120.00 ( 0.00%) 99.00 ( 17.50%) Min free-odr0-8 106.00 ( 0.00%) 85.00 ( 19.81%) Min free-odr0-16 97.00 ( 0.00%) 80.00 ( 17.53%) Min free-odr0-32 92.00 ( 0.00%) 76.00 ( 17.39%) Min free-odr0-64 89.00 ( 0.00%) 74.00 ( 16.85%) Min free-odr0-128 89.00 ( 0.00%) 73.00 ( 17.98%) Min free-odr0-256 107.00 ( 0.00%) 90.00 ( 15.89%) Min free-odr0-512 117.00 ( 0.00%) 108.00 ( 7.69%) Min free-odr0-1024 125.00 ( 0.00%) 118.00 ( 5.60%) Min free-odr0-2048 132.00 ( 0.00%) 125.00 ( 5.30%) Min free-odr0-4096 135.00 ( 0.00%) 130.00 ( 3.70%) Min free-odr0-8192 137.00 ( 0.00%) 130.00 ( 5.11%) Min free-odr0-16384 137.00 ( 0.00%) 131.00 ( 4.38%) Min free-odr1-1 318.00 ( 0.00%) 289.00 ( 9.12%) Min free-odr1-2 228.00 ( 0.00%) 207.00 ( 9.21%) Min free-odr1-4 182.00 ( 0.00%) 165.00 ( 9.34%) Min free-odr1-8 163.00 ( 0.00%) 146.00 ( 10.43%) Min free-odr1-16 151.00 ( 0.00%) 135.00 ( 10.60%) Min free-odr1-32 146.00 ( 0.00%) 129.00 ( 11.64%) Min free-odr1-64 145.00 ( 0.00%) 130.00 ( 10.34%) Min free-odr1-128 148.00 ( 0.00%) 134.00 ( 9.46%) Min free-odr1-256 148.00 ( 0.00%) 137.00 ( 7.43%) Min free-odr1-512 151.00 ( 0.00%) 140.00 ( 7.28%) Min free-odr1-1024 154.00 ( 0.00%) 143.00 ( 7.14%) Min free-odr1-2048 156.00 ( 0.00%) 144.00 ( 7.69%) Min free-odr1-4096 156.00 ( 0.00%) 142.00 ( 8.97%) Min free-odr1-8192 156.00 ( 0.00%) 140.00 ( 10.26%) Min free-odr2-1 361.00 ( 0.00%) 457.00 (-26.59%) Min free-odr2-2 258.00 ( 0.00%) 224.00 ( 13.18%) Min free-odr2-4 208.00 ( 0.00%) 223.00 ( -7.21%) Min free-odr2-8 185.00 ( 0.00%) 160.00 ( 13.51%) Min free-odr2-16 173.00 ( 0.00%) 149.00 ( 13.87%) Min free-odr2-32 166.00 ( 0.00%) 145.00 ( 12.65%) Min free-odr2-64 166.00 ( 0.00%) 146.00 ( 12.05%) Min free-odr2-128 169.00 ( 0.00%) 148.00 ( 12.43%) Min free-odr2-256 170.00 ( 0.00%) 152.00 ( 10.59%) Min free-odr2-512 177.00 ( 0.00%) 156.00 ( 11.86%) Min free-odr2-1024 182.00 ( 0.00%) 162.00 ( 10.99%) Min free-odr2-2048 181.00 ( 0.00%) 160.00 ( 11.60%) Min free-odr2-4096 180.00 ( 0.00%) 159.00 ( 11.67%) Min free-odr3-1 431.00 ( 0.00%) 367.00 ( 14.85%) Min free-odr3-2 306.00 ( 0.00%) 259.00 ( 15.36%) Min free-odr3-4 249.00 ( 0.00%) 208.00 ( 16.47%) Min free-odr3-8 224.00 ( 0.00%) 186.00 ( 16.96%) Min free-odr3-16 208.00 ( 0.00%) 176.00 ( 15.38%) Min free-odr3-32 206.00 ( 0.00%) 174.00 ( 15.53%) Min free-odr3-64 210.00 ( 0.00%) 178.00 ( 15.24%) Min free-odr3-128 215.00 ( 0.00%) 182.00 ( 15.35%) Min free-odr3-256 224.00 ( 0.00%) 189.00 ( 15.62%) Min free-odr3-512 232.00 ( 0.00%) 195.00 ( 15.95%) Min free-odr3-1024 230.00 ( 0.00%) 195.00 ( 15.22%) Min free-odr3-2048 229.00 ( 0.00%) 193.00 ( 15.72%) Min free-odr4-1 561.00 ( 0.00%) 439.00 ( 21.75%) Min free-odr4-2 418.00 ( 0.00%) 318.00 ( 23.92%) Min free-odr4-4 339.00 ( 0.00%) 269.00 ( 20.65%) Min free-odr4-8 299.00 ( 0.00%) 239.00 ( 20.07%) Min free-odr4-16 289.00 ( 0.00%) 234.00 ( 19.03%) Min free-odr4-32 291.00 ( 0.00%) 235.00 ( 19.24%) Min free-odr4-64 298.00 ( 0.00%) 238.00 ( 20.13%) Min free-odr4-128 308.00 ( 0.00%) 251.00 ( 18.51%) Min free-odr4-256 321.00 ( 0.00%) 267.00 ( 16.82%) Min free-odr4-512 327.00 ( 0.00%) 269.00 ( 17.74%) Min free-odr4-1024 326.00 ( 0.00%) 271.00 ( 16.87%) Min total-odr0-1 644.00 ( 0.00%) 494.00 ( 23.29%) Min total-odr0-2 466.00 ( 0.00%) 356.00 ( 23.61%) Min total-odr0-4 376.00 ( 0.00%) 291.00 ( 22.61%) Min total-odr0-8 328.00 ( 0.00%) 251.00 ( 23.48%) Min total-odr0-16 304.00 ( 0.00%) 234.00 ( 23.03%) Min total-odr0-32 289.00 ( 0.00%) 224.00 ( 22.49%) Min total-odr0-64 282.00 ( 0.00%) 218.00 ( 22.70%) Min total-odr0-128 280.00 ( 0.00%) 216.00 ( 22.86%) Min total-odr0-256 310.00 ( 0.00%) 243.00 ( 21.61%) Min total-odr0-512 329.00 ( 0.00%) 273.00 ( 17.02%) Min total-odr0-1024 346.00 ( 0.00%) 290.00 ( 16.18%) Min total-odr0-2048 357.00 ( 0.00%) 304.00 ( 14.85%) Min total-odr0-4096 367.00 ( 0.00%) 315.00 ( 14.17%) Min total-odr0-8192 372.00 ( 0.00%) 317.00 ( 14.78%) Min total-odr0-16384 373.00 ( 0.00%) 319.00 ( 14.48%) Min total-odr1-1 838.00 ( 0.00%) 739.00 ( 11.81%) Min total-odr1-2 619.00 ( 0.00%) 543.00 ( 12.28%) Min total-odr1-4 495.00 ( 0.00%) 433.00 ( 12.53%) Min total-odr1-8 440.00 ( 0.00%) 382.00 ( 13.18%) Min total-odr1-16 407.00 ( 0.00%) 353.00 ( 13.27%) Min total-odr1-32 398.00 ( 0.00%) 341.00 ( 14.32%) Min total-odr1-64 389.00 ( 0.00%) 336.00 ( 13.62%) Min total-odr1-128 392.00 ( 0.00%) 341.00 ( 13.01%) Min total-odr1-256 391.00 ( 0.00%) 344.00 ( 12.02%) Min total-odr1-512 396.00 ( 0.00%) 349.00 ( 11.87%) Min total-odr1-1024 402.00 ( 0.00%) 357.00 ( 11.19%) Min total-odr1-2048 409.00 ( 0.00%) 364.00 ( 11.00%) Min total-odr1-4096 414.00 ( 0.00%) 366.00 ( 11.59%) Min total-odr1-8192 417.00 ( 0.00%) 369.00 ( 11.51%) Min total-odr2-1 921.00 ( 0.00%) 1210.00 (-31.38%) Min total-odr2-2 682.00 ( 0.00%) 576.00 ( 15.54%) Min total-odr2-4 547.00 ( 0.00%) 616.00 (-12.61%) Min total-odr2-8 483.00 ( 0.00%) 406.00 ( 15.94%) Min total-odr2-16 449.00 ( 0.00%) 376.00 ( 16.26%) Min total-odr2-32 437.00 ( 0.00%) 366.00 ( 16.25%) Min total-odr2-64 431.00 ( 0.00%) 363.00 ( 15.78%) Min total-odr2-128 433.00 ( 0.00%) 365.00 ( 15.70%) Min total-odr2-256 434.00 ( 0.00%) 371.00 ( 14.52%) Min total-odr2-512 446.00 ( 0.00%) 379.00 ( 15.02%) Min total-odr2-1024 461.00 ( 0.00%) 392.00 ( 14.97%) Min total-odr2-2048 464.00 ( 0.00%) 395.00 ( 14.87%) Min total-odr2-4096 465.00 ( 0.00%) 398.00 ( 14.41%) Min total-odr3-1 1060.00 ( 0.00%) 872.00 ( 17.74%) Min total-odr3-2 778.00 ( 0.00%) 633.00 ( 18.64%) Min total-odr3-4 632.00 ( 0.00%) 510.00 ( 19.30%) Min total-odr3-8 565.00 ( 0.00%) 452.00 ( 20.00%) Min total-odr3-16 524.00 ( 0.00%) 424.00 ( 19.08%) Min total-odr3-32 514.00 ( 0.00%) 415.00 ( 19.26%) Min total-odr3-64 515.00 ( 0.00%) 419.00 ( 18.64%) Min total-odr3-128 523.00 ( 0.00%) 426.00 ( 18.55%) Min total-odr3-256 541.00 ( 0.00%) 438.00 ( 19.04%) Min total-odr3-512 559.00 ( 0.00%) 451.00 ( 19.32%) Min total-odr3-1024 561.00 ( 0.00%) 456.00 ( 18.72%) Min total-odr3-2048 562.00 ( 0.00%) 459.00 ( 18.33%) Min total-odr4-1 1328.00 ( 0.00%) 1011.00 ( 23.87%) Min total-odr4-2 997.00 ( 0.00%) 747.00 ( 25.08%) Min total-odr4-4 813.00 ( 0.00%) 615.00 ( 24.35%) Min total-odr4-8 721.00 ( 0.00%) 550.00 ( 23.72%) Min total-odr4-16 689.00 ( 0.00%) 529.00 ( 23.22%) Min total-odr4-32 683.00 ( 0.00%) 528.00 ( 22.69%) Min total-odr4-64 692.00 ( 0.00%) 531.00 ( 23.27%) Min total-odr4-128 713.00 ( 0.00%) 556.00 ( 22.02%) Min total-odr4-256 738.00 ( 0.00%) 586.00 ( 20.60%) Min total-odr4-512 753.00 ( 0.00%) 595.00 ( 20.98%) Min total-odr4-1024 752.00 ( 0.00%) 600.00 ( 20.21%) This patch (of 27): order-0 pages by definition cannot be compound so avoid the check in the fast path for those pages. [akpm@linux-foundation.org: use unlikely(order) in free_pages_prepare(), per Vlastimil] Signed-off-by: -
Michal Hocko authored
Right now the oom reaper will clear TIF_MEMDIE only for tasks which were successfully reaped. This is the safest option because we know that such an oom victim would only block forward progress of the oom killer without a good reason because it is highly unlikely it would release much more memory. Basically most of its memory has been already torn down. We can relax this assumption to catch more corner cases though. The first obvious one is when the oom victim clears its mm and gets stuck later on. oom_reaper would back of on find_lock_task_mm returning NULL. We can safely try to clear TIF_MEMDIE in this case because such a task would be ignored by the oom killer anyway. The flag would be cleared by that time already most of the time anyway. The less obvious one is when the oom reaper fails due to mmap_sem contention. Even if we clear TIF_MEMDIE for this task then it is not very likely that we would select another task too easily because we haven't reaped the last victim and so it would be still the #1 candidate. There is a rare race condition possible when the current victim terminates before the next select_bad_process but considering that oom_reap_task had retried several times before giving up then this sounds like a borderline thing. After this patch we should have a guarantee that the OOM killer will not be block for unbounded amount of time for most cases. Signed-off-by:
Michal Hocko <mhocko@suse.com> Cc: Raushaniya Maksudova <rmaksudova@parallels.com> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by:
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Michal Hocko authored
If either the current task is already killed or PF_EXITING or a selected task is PF_EXITING then the oom killer is suppressed and so is the oom reaper. This patch adds try_oom_reaper which checks the given task and queues it for the oom reaper if that is safe to be done meaning that the task doesn't share the mm with an alive process. This might help to release the memory pressure while the task tries to exit. [akpm@linux-foundation.org: fix nommu build] Signed-off-by:
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Michal Hocko authored
__alloc_pages_may_oom is the central place to decide when the out_of_memory should be invoked. This is a good approach for most checks there because they are page allocator specific and the allocation fails right after for all of them. The notable exception is GFP_NOFS context which is faking did_some_progress and keep the page allocator looping even though there couldn't have been any progress from the OOM killer. This patch doesn't change this behavior because we are not ready to allow those allocation requests to fail yet (and maybe we will face the reality that we will never manage to safely fail these request). Instead __GFP_FS check is moved down to out_of_memory and prevent from OOM victim selection there. There are two reasons for that - OOM notifiers might release some memory even from this context as none of the registered notifier seems to be FS related - this might help a dying thread to get an access to memory reserves and move on which will make the behavior more consistent with the case when the task gets killed from a different context. Keep a comment in __alloc_pages_may_oom to make sure we do not forget how GFP_NOFS is special and that we really want to do something about it. Note to the current oom_notifier users: The observable difference for you is that oom notifiers cannot depend on any fs locks because we could deadlock. Not that this would be allowed today because that would just lockup machine in most of the cases and ruling out the OOM killer along the way. Another difference is that callbacks might be invoked sooner now because GFP_NOFS is a weaker reclaim context and so there could be reclaimable memory which is just not reachable now. That would require GFP_NOFS only loads which are really rare and more importantly the observable result would be dropping of reconstructible object and potential performance drop which is not such a big deal when we are struggling to fulfill other important allocation requests. Signed-off-by: -
Vitaly Kuznetsov authored
CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE specifies the default value for the memory hotplug onlining policy. Add a command line parameter to make it possible to override the default. It may come handy for debug and testing purposes. Signed-off-by:
Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Dan Williams <dan.j.williams@intel.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: David Vrabel <david.vrabel@citrix.com> Cc: David Rientjes <rientjes@google.com> Cc: Igor Mammedov <imammedo@redhat.com> Cc: Lennart Poettering <lennart@poettering.net> Signed-off-by:
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Vitaly Kuznetsov authored
This patchset continues the work I started with commit 31bc3858 ("memory-hotplug: add automatic onlining policy for the newly added memory"). Initially I was going to stop there and bring the policy setting logic to userspace. I met two issues on this way: 1) It is possible to have memory hotplugged at boot (e.g. with QEMU). These blocks stay offlined if we turn the onlining policy on by userspace. 2) My attempt to bring this policy setting to systemd failed, systemd maintainers suggest to change the default in kernel or ... to use tmpfiles.d to alter the policy (which looks like a hack to me): https://github.com/systemd/systemd/pull/2938 Here I suggest to add a config option to set the default value for the policy and a kernel command line parameter to make the override. This patch (of 2): Introduce config option to set the default value for memory hotplug onlining policy (/sys/devices/system/memory/auto_online_blocks). The reason one would want to turn this option on are to have early onlining for hotpluggable memory available at boot and to not require any userspace actions to make memory hotplug work. [akpm@linux-foundation.org: tweak Kconfig text] Signed-off-by:
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Hugh Dickins authored
I've just discovered that the useful-sounding has_transparent_hugepage() is actually an architecture-dependent minefield: on some arches it only builds if CONFIG_TRANSPARENT_HUGEPAGE=y, on others it's also there when not, but on some of those (arm and arm64) it then gives the wrong answer; and on mips alone it's marked __init, which would crash if called later (but so far it has not been called later). Straighten this out: make it available to all configs, with a sensible default in asm-generic/pgtable.h, removing its definitions from those arches (arc, arm, arm64, sparc, tile) which are served by the default, adding #define has_transparent_hugepage has_transparent_hugepage to those (mips, powerpc, s390, x86) which need to override the default at runtime, and removing the __init from mips (but maybe that kind of code should be avoided after init: set a static variable the first time it's called). Signed-off-by:
Hugh Dickins <hughd@google.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andres Lagar-Cavilla <andreslc@google.com> Cc: Yang Shi <yang.shi@linaro.org> Cc: Ning Qu <quning@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Acked-by:
David S. Miller <davem@davemloft.net> Acked-by: Vineet Gupta <vgupta@synopsys.com> [arch/arc] Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [arch/s390] Acked-by:
Ingo Molnar <mingo@kernel.org> Signed-off-by:
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Hugh Dickins authored
Whatever huge pagecache implementation we go with, file rmap locking must be added to anon rmap locking, when mremap's move_page_tables() finds a pmd_trans_huge pmd entry: a simple change, let's do it now. Factor out take_rmap_locks() and drop_rmap_locks() to handle the locking for make move_ptes() and move_page_tables(), and delete the VM_BUG_ON_VMA which rejected vm_file and required anon_vma. Signed-off-by:
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Hugh Dickins authored
Remove move_huge_pmd()'s redundant new_vma arg: all it was used for was a VM_NOHUGEPAGE check on new_vma flags, but the new_vma is cloned from the old vma, so a trans_huge_pmd in the new_vma will be as acceptable as it was in the old vma, alignment and size permitting. Signed-off-by:
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Hugh Dickins authored
Provide /proc/sys/vm/stat_refresh to force an immediate update of per-cpu into global vmstats: useful to avoid a sleep(2) or whatever before checking counts when testing. Originally added to work around a bug which left counts stranded indefinitely on a cpu going idle (an inaccuracy magnified when small below-batch numbers represent "huge" amounts of memory), but I believe that bug is now fixed: nonetheless, this is still a useful knob. Its schedule_on_each_cpu() is probably too expensive just to fold into reading /proc/meminfo itself: give this mode 0600 to prevent abuse. Allow a write or a read to do the same: nothing to read, but "grep -h Shmem /proc/sys/vm/stat_refresh /proc/meminfo" is convenient. Oh, and since global_page_state() itself is careful to disguise any underflow as 0, hack in an "Invalid argument" and pr_warn() if a counter is negative after the refresh - this helped to fix a misaccounting of NR_ISOLATED_FILE in my migration code. But on recent kernels, I find that NR_ALLOC_BATCH and NR_PAGES_SCANNED often go negative some of the time. I have not yet worked out why, but have no evidence that it's actually harmful. Punt for the moment by just ignoring the anomaly on those. Signed-off-by:
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Andres Lagar-Cavilla authored
Although shmem_fault() has been careful to count a major fault to vm_mm, shmem_getpage_gfp() has been careless in charging a remote access fault to current->mm owner's memcg instead of to vma->vm_mm owner's memcg: that is inconsistent with all the mem_cgroup charging on remote access faults in mm/memory.c. Fix it by passing fault_mm along with fault_type to shmem_get_page_gfp(); but in that case, now knowing the right mm, it's better for it to handle the PGMAJFAULT updates itself. And let's keep this clutter out of most callers' way: change the common shmem_getpage() wrapper to hide fault_mm and fault_type as well as gfp. Signed-off-by:
Andres Lagar-Cavilla <andreslc@google.com> Signed-off-by:
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Hugh Dickins authored
Make a few cleanups in mm/shmem.c, before going on to complicate it. shmem_alloc_page() will become more complicated: we can't afford to to have that complication duplicated between a CONFIG_NUMA version and a !CONFIG_NUMA version, so rearrange the #ifdef'ery there to yield a single shmem_swapin() and a single shmem_alloc_page(). Yes, it's a shame to inflict the horrid pseudo-vma on non-NUMA configurations, but eliminating it is a larger cleanup: I have an alloc_pages_mpol() patchset not yet ready - mpol handling is subtle and bug-prone, and changed yet again since my last version. Move __SetPageLocked, __SetPageSwapBacked from shmem_getpage_gfp() to shmem_alloc_page(): that SwapBacked flag will be useful in future, to help to distinguish different cases appropriately. And the SGP_DIRTY variant of SGP_CACHE is hard to understand and of little use (IIRC it dates back to when shmem_getpage() returned the page unlocked): kill it and do the necessary in shmem_file_read_iter(). But an arm64 build then complained that info may be uninitialized (where shmem_getpage_gfp() deletes a freshly alloced page beyond eof), and advancing to an "sgp <= SGP_CACHE" test jogged it back to reality. Signed-off-by:
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Hugh Dickins authored
v3.16 commit 07a42788 ("mm: shmem: avoid atomic operation during shmem_getpage_gfp") rightly replaced one instance of SetPageSwapBacked by __SetPageSwapBacked, pointing out that the newly allocated page is not yet visible to other users (except speculative get_page_unless_zero- ers, who may not update page flags before their further checks). That was part of a series in which Mel was focused on tmpfs profiles: but almost all SetPageSwapBacked uses can be so optimized, with the same justification. Remove ClearPageSwapBacked from __read_swap_cache_async() error path: it's not an error to free a page with PG_swapbacked set. Follow a convention of __SetPageLocked, __SetPageSwapBacked instead of doing it differently in different places; but that's for tidiness - if the ordering actually mattered, we should not be using the __variants. There's probably scope for further __SetPageFlags in other places, but SwapBacked is the one I'm interested in at the moment. Signed-off-by:
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