Revision 441c228f817f7597e090d84aca74bdb7c2bd5040 authored by Mel Gorman on 13 December 2014, 00:56:33 UTC, committed by Linus Torvalds on 13 December 2014, 20:42:49 UTC
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>
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| File | Mode | Size |
|---|---|---|
| Makefile | -rw-r--r-- | 394 bytes |
| compat.c | -rw-r--r-- | 19.1 KB |
| compat_mq.c | -rw-r--r-- | 3.9 KB |
| ipc_sysctl.c | -rw-r--r-- | 7.0 KB |
| ipcns_notifier.c | -rw-r--r-- | 2.2 KB |
| mq_sysctl.c | -rw-r--r-- | 2.9 KB |
| mqueue.c | -rw-r--r-- | 35.3 KB |
| msg.c | -rw-r--r-- | 23.9 KB |
| msgutil.c | -rw-r--r-- | 3.6 KB |
| namespace.c | -rw-r--r-- | 4.7 KB |
| sem.c | -rw-r--r-- | 55.0 KB |
| shm.c | -rw-r--r-- | 32.1 KB |
| syscall.c | -rw-r--r-- | 2.3 KB |
| util.c | -rw-r--r-- | 22.2 KB |
| util.h | -rw-r--r-- | 6.4 KB |
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