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| author | Mel Gorman | 2014-12-13 01:56:33 +0100 |
|---|---|---|
| committer | Linus Torvalds | 2014-12-13 21:42:49 +0100 |
| commit | 441c228f817f7597e090d84aca74bdb7c2bd5040 (patch) | |
| tree | 2b03cb17475aeb302d230e4c36dcd18a374a05f6 /mm/memcontrol.c | |
| parent | mm/vmalloc.c: fix memory ordering bug (diff) | |
| download | kernel-qcow2-linux-441c228f817f7597e090d84aca74bdb7c2bd5040.tar.gz kernel-qcow2-linux-441c228f817f7597e090d84aca74bdb7c2bd5040.tar.xz kernel-qcow2-linux-441c228f817f7597e090d84aca74bdb7c2bd5040.zip | |
mm: fadvise: document the fadvise(FADV_DONTNEED) behaviour for partial pages
A random seek IO benchmark appeared to regress because of a change to
readahead but the real problem was the benchmark. To ensure the IO
request accesssed disk, it used fadvise(FADV_DONTNEED) on a block boundary
(512K) but the hint is ignored by the kernel. This is correct but not
necessarily obvious behaviour. As much as I dislike comment patches, the
explanation for this behaviour predates current git history. Clarify why
it behaves like this in case someone "fixes" fadvise or readahead for the
wrong reasons.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol.c')
0 files changed, 0 insertions, 0 deletions