[PATCH 2/2] cfq: allow dispatching of both sync and async I/O together
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From: Jeff Moyer on 21 Jun 2010 16:00 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(a)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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |