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| author |   Mel Gorman <mgorman@techsingularity.net> | 2019-03-05 15:45:41 -0800 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2019-03-05 21:07:17 -0800 |
| commit | 5e1f0f098b4649fad53011246bcaeff011ffdf5d (patch) | |
| tree | 88e1399008fd89a44a52b3dabb6da42eef15da05 /include/linux/sched.h | |
| parent | mm, compaction: be selective about what pageblocks to clear skip hints (diff) | |
| download | linux-dev-5e1f0f098b4649fad53011246bcaeff011ffdf5d.tar.xz linux-dev-5e1f0f098b4649fad53011246bcaeff011ffdf5d.zip | |
mm, compaction: capture a page under direct compaction
Compaction is inherently race-prone as a suitable page freed during
compaction can be allocated by any parallel task. This patch uses a
capture_control structure to isolate a page immediately when it is freed
by a direct compactor in the slow path of the page allocator. The
intent is to avoid redundant scanning.
5.0.0-rc1 5.0.0-rc1
selective-v3r17 capture-v3r19
Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%*
Amean fault-both-3 2582.11 ( 0.00%) 2563.68 ( 0.71%)
Amean fault-both-5 4500.26 ( 0.00%) 4233.52 ( 5.93%)
Amean fault-both-7 5819.53 ( 0.00%) 6333.65 ( -8.83%)
Amean fault-both-12 9321.18 ( 0.00%) 9759.38 ( -4.70%)
Amean fault-both-18 9782.76 ( 0.00%) 10338.76 ( -5.68%)
Amean fault-both-24 15272.81 ( 0.00%) 13379.55 * 12.40%*
Amean fault-both-30 15121.34 ( 0.00%) 16158.25 ( -6.86%)
Amean fault-both-32 18466.67 ( 0.00%) 18971.21 ( -2.73%)
Latency is only moderately affected but the devil is in the details. A
closer examination indicates that base page fault latency is reduced but
latency of huge pages is increased as it takes creater care to succeed.
Part of the "problem" is that allocation success rates are close to 100%
even when under pressure and compaction gets harder
5.0.0-rc1 5.0.0-rc1
selective-v3r17 capture-v3r19
Percentage huge-3 96.70 ( 0.00%) 98.23 ( 1.58%)
Percentage huge-5 96.99 ( 0.00%) 95.30 ( -1.75%)
Percentage huge-7 94.19 ( 0.00%) 97.24 ( 3.24%)
Percentage huge-12 94.95 ( 0.00%) 97.35 ( 2.53%)
Percentage huge-18 96.74 ( 0.00%) 97.30 ( 0.58%)
Percentage huge-24 97.07 ( 0.00%) 97.55 ( 0.50%)
Percentage huge-30 95.69 ( 0.00%) 98.50 ( 2.95%)
Percentage huge-32 96.70 ( 0.00%) 99.27 ( 2.65%)
And scan rates are reduced as expected by 6% for the migration scanner
and 29% for the free scanner indicating that there is less redundant
work.
Compaction migrate scanned 20815362 19573286
Compaction free scanned 16352612 11510663
[mgorman@techsingularity.net: remove redundant check]
Link: http://lkml.kernel.org/r/20190201143853.GH9565@techsingularity.net
Link: http://lkml.kernel.org/r/20190118175136.31341-23-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/sched.h')
| -rw-r--r-- | include/linux/sched.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index f9b43c989577..ebfb34fb9b30 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -47,6 +47,7 @@ struct pid_namespace; struct pipe_inode_info; struct rcu_node; struct reclaim_state; +struct capture_control; struct robust_list_head; struct sched_attr; struct sched_param; @@ -958,6 +959,9 @@ struct task_struct { struct io_context *io_context; +#ifdef CONFIG_COMPACTION + struct capture_control *capture_control; +#endif /* Ptrace state: */ unsigned long ptrace_message; kernel_siginfo_t *last_siginfo; |