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mm: make swapin readahead to improve thp collapse rate

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This patch makes swapin readahead to improve thp collapse rate.  When
khugepaged scanned pages, there can be a few of the pages in swap area.

With the patch THP can collapse 4kB pages into a THP when there are up
to max_ptes_swap swap ptes in a 2MB range.

The patch was tested with a test program that allocates 400B of memory,
writes to it, and then sleeps.  I force the system to swap out all.
Afterwards, the test program touches the area by writing, it skips a
page in each 20 pages of the area.

Without the patch, system did not swap in readahead.  THP rate was %65
of the program of the memory, it did not change over time.

With this patch, after 10 minutes of waiting khugepaged had collapsed
%99 of the program's memory.

[kirill.shutemov@linux.intel.com: trivial cleanup of exit path of the function]
[kirill.shutemov@linux.intel.com: __collapse_huge_page_swapin(): drop unused 'pte' parameter]
[kirill.shutemov@linux.intel.com: do not hold anon_vma lock during swap in]
Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Xie XiuQi <xiexiuqi@huawei.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: David Rientjes <rientjes@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ebru Akagunduz
2016-07-26 15:25:03 -07:00
committed by Linus Torvalds
parent 70652f6ec0
commit 8a966ed746
4 changed files with 69 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
include/trace/events/huge_memory.h
View File

@@ -135,5 +135,29 @@ TRACE_EVENT(mm_collapse_huge_page_isolate,
__print_symbolic(__entry->status, SCAN_STATUS))
);
TRACE_EVENT(mm_collapse_huge_page_swapin,
TP_PROTO(struct mm_struct *mm, int swapped_in, int ret),
TP_ARGS(mm, swapped_in, ret),
TP_STRUCT__entry(
__field(struct mm_struct *, mm)
__field(int, swapped_in)
__field(int, ret)
),
TP_fast_assign(
__entry->mm = mm;
__entry->swapped_in = swapped_in;
__entry->ret = ret;
),
TP_printk("mm=%p, swapped_in=%d, ret=%d",
__entry->mm,
__entry->swapped_in,
__entry->ret)
);
#endif /* __HUGE_MEMORY_H */
#include <trace/define_trace.h>