Messages in this thread Patch in this message | | | From | Jeff Moyer <> | Subject | [PATCH 2/2] cfq: allow dispatching of both sync and async I/O together | Date | Mon, 21 Jun 2010 15:49:49 -0400 |
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Hi,
In testing a workload that has a single fsync-ing process and another process that does a sequential buffered read, I was unable to tune CFQ to reach the throughput of deadline. This patch, along with the previous one, brought CFQ in line with deadline when setting slice_idle to 0.
I'm not sure what the original reason for not allowing sync and async I/O to be dispatched together was. If there is a workload I should be testing that shows the inherent problems of this, please point me at it and I will resume testing. Until and unless that workload is identified, please consider applying this patch.
Cheers, Jeff
Signed-off-by: Jeff Moyer <jmoyer@redhat.com> --- block/cfq-iosched.c | 12 ------------ 1 files changed, 0 insertions(+), 12 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 572a050..dab836e 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -2296,18 +2296,6 @@ static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) { unsigned int max_dispatch; - /* - * Drain async requests before we start sync IO - */ - if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC]) - return false; - - /* - * If this is an async queue and we have sync IO in flight, let it wait - */ - if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq)) - return false; - max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1); if (cfq_class_idle(cfqq)) max_dispatch = 1; -- 1.6.5.2
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