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| author | Jeff Moyer <jmoyer@redhat.com> | 2011-11-02 13:40:10 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-11-02 16:07:03 -0700 |
| commit | 080d676de095a14ecba14c0b9a91acb5bbb634df (patch) | |
| tree | 4a4c56bc86a8edf4a42f8ec7c65ba795997e50ab /include/linux/aio.h | |
| parent | 2ca02df6b098be2d33a99a65531dcd84a10b6e21 (diff) | |
| download | lwn-080d676de095a14ecba14c0b9a91acb5bbb634df.tar.gz lwn-080d676de095a14ecba14c0b9a91acb5bbb634df.zip | |
aio: allocate kiocbs in batches
In testing aio on a fast storage device, I found that the context lock
takes up a fair amount of cpu time in the I/O submission path. The reason
is that we take it for every I/O submitted (see __aio_get_req). Since we
know how many I/Os are passed to io_submit, we can preallocate the kiocbs
in batches, reducing the number of times we take and release the lock.
In my testing, I was able to reduce the amount of time spent in
_raw_spin_lock_irq by .56% (average of 3 runs). The command I used to
test this was:
aio-stress -O -o 2 -o 3 -r 8 -d 128 -b 32 -i 32 -s 16384 <dev>
I also tested the patch with various numbers of events passed to
io_submit, and I ran the xfstests aio group of tests to ensure I didn't
break anything.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Daniel Ehrenberg <dehrenberg@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/aio.h')
| -rw-r--r-- | include/linux/aio.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/aio.h b/include/linux/aio.h index 2dcb72bff4b6..2314ad8b3c9c 100644 --- a/include/linux/aio.h +++ b/include/linux/aio.h @@ -117,6 +117,7 @@ struct kiocb { struct list_head ki_list; /* the aio core uses this * for cancellation */ + struct list_head ki_batch; /* batch allocation */ /* * If the aio_resfd field of the userspace iocb is not zero, |