tree ebe8e0c616a9dbfdfe5184b64d0150ea02d3d1b2
parent 644b2d99b7a8677a56909a7b1fde31677eba4471
author Jens Axboe <jens.axboe@oracle.com> 1239022087 +0200
committer Linus Torvalds <torvalds@linux-foundation.org> 1239030294 -0700

block: Add flag for telling the IO schedulers NOT to anticipate more IO

By default, CFQ will anticipate more IO from a given io context if the
previously completed IO was sync. This used to be fine, since the only
sync IO was reads and O_DIRECT writes. But with more "normal" sync writes
being used now, we don't want to anticipate for those.

Add a bio/request flag that informs the IO scheduler that this is a sync
request that we should not idle for. Introduce WRITE_ODIRECT specifically
for O_DIRECT writes, and make sure that the other sync writes set this
flag.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>