diff options
| author | Mel Gorman <mgorman@techsingularity.net> | 2021-06-29 05:42:18 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-06-29 20:53:54 +0300 |
| commit | 3b12e7e97938424de2bb1b95ba0bd6a49bad39f9 (patch) | |
| tree | 8950f0935651b627b186eb44eb56854e07bff962 /include/linux/mmzone.h | |
| parent | 04f8cfeaed0849e702278378bce3867577ca45fb (diff) | |
| download | linux-3b12e7e97938424de2bb1b95ba0bd6a49bad39f9.tar.xz | |
mm/page_alloc: scale the number of pages that are batch freed
When a task is freeing a large number of order-0 pages, it may acquire the
zone->lock multiple times freeing pages in batches. This may
unnecessarily contend on the zone lock when freeing very large number of
pages. This patch adapts the size of the batch based on the recent
pattern to scale the batch size for subsequent frees.
As the machines I used were not large enough to test this are not large
enough to illustrate a problem, a debugging patch shows patterns like the
following (slightly editted for clarity)
Baseline vanilla kernel
time-unmap-14426 [...] free_pcppages_bulk: free 63 count 378 high 378
time-unmap-14426 [...] free_pcppages_bulk: free 63 count 378 high 378
time-unmap-14426 [...] free_pcppages_bulk: free 63 count 378 high 378
time-unmap-14426 [...] free_pcppages_bulk: free 63 count 378 high 378
time-unmap-14426 [...] free_pcppages_bulk: free 63 count 378 high 378
With patches
time-unmap-7724 [...] free_pcppages_bulk: free 126 count 814 high 814
time-unmap-7724 [...] free_pcppages_bulk: free 252 count 814 high 814
time-unmap-7724 [...] free_pcppages_bulk: free 504 count 814 high 814
time-unmap-7724 [...] free_pcppages_bulk: free 751 count 814 high 814
time-unmap-7724 [...] free_pcppages_bulk: free 751 count 814 high 814
Link: https://lkml.kernel.org/r/20210525080119.5455-5-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/mmzone.h')
| -rw-r--r-- | include/linux/mmzone.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 7937a1d1d166..0a86b2890a16 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -343,8 +343,9 @@ struct per_cpu_pages { int count; /* number of pages in the list */ int high; /* high watermark, emptying needed */ int batch; /* chunk size for buddy add/remove */ + short free_factor; /* batch scaling factor during free */ #ifdef CONFIG_NUMA - int expire; /* When 0, remote pagesets are drained */ + short expire; /* When 0, remote pagesets are drained */ #endif /* Lists of pages, one per migrate type stored on the pcp-lists */ |