diff options
| author | Mel Gorman <mgorman@suse.de> | 2014-12-12 16:56:33 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-12-13 12:42:49 -0800 |
| commit | 441c228f817f7597e090d84aca74bdb7c2bd5040 (patch) | |
| tree | 2b03cb17475aeb302d230e4c36dcd18a374a05f6 /virt | |
| parent | 7e5b528b4ce31208ef5c240c14beec4853d8262c (diff) | |
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 'virt')
0 files changed, 0 insertions, 0 deletions