tree 3783ea1ef788f564a78754906dc508ac66595b75
parent b9099ff63c75216d6ca10bce5a1abcd9293c27e6
author Jens Axboe <jens.axboe@oracle.com> 1171479589 +0100
committer Jens Axboe <axboe@nelson.home.kernel.dk> 1177916481 +0200

cfq-iosched: improve preemption for cooperating tasks

When testing the syslet async io approach, I discovered that CFQ
sometimes didn't perform as well as expected. cfq_should_preempt()
needs to better check for cooperating tasks, so fix that by allowing
preemption of an equal priority queue if the recently queued request
is as good a candidate for IO as the one we are currently waiting for.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>