cfq-iosched: delay async IO dispatch, if sync IO was just done (365722bb) · Commits · 戴 / test

block/cfq-iosched.c

+16 −2

Original line number	Diff line number	Diff line
		@@ -181,6 +181,8 @@ struct cfq_data {
		* Fallback dummy cfqq for extreme OOM conditions
		*/
		struct cfq_queue oom_cfqq;

		unsigned long last_end_sync_rq;
		};

		enum cfqq_state_flags {
		@@ -1314,6 +1316,8 @@ static int cfq_dispatch_requests(struct request_queue *q, int force)
		* Does this cfqq already have too much IO in flight?
		*/
		if (cfqq->dispatched >= max_dispatch) {
		unsigned long load_at = cfqd->last_end_sync_rq + cfq_slice_sync;

		/*
		* idle queue must always only have a single IO in flight
		*/
		@@ -1326,6 +1330,14 @@ static int cfq_dispatch_requests(struct request_queue *q, int force)
		if (cfqd->busy_queues > 1)
		return 0;

		/*
		* If a sync request has completed recently, don't overload
		* the dispatch queue yet with async requests.
		*/
		if (cfqd->cfq_desktop && !cfq_cfqq_sync(cfqq)
		&& time_before(jiffies, load_at))
		return 0;

		/*
		* we are the only queue, allow up to 4 times of 'quantum'
		*/
		@@ -2158,8 +2170,10 @@ static void cfq_completed_request(struct request_queue q, struct request rq)
		if (cfq_cfqq_sync(cfqq))
		cfqd->sync_flight--;

		if (sync)
		if (sync) {
		RQ_CIC(rq)->last_end_request = now;
		cfqd->last_end_sync_rq = now;
		}

		/*
		* If this is the active queue, check if it needs to be expired,
		@@ -2483,7 +2497,7 @@ static void cfq_init_queue(struct request_queue q)
		cfqd->cfq_slice_idle = cfq_slice_idle;
		cfqd->cfq_desktop = 1;
		cfqd->hw_tag = 1;

		cfqd->last_end_sync_rq = jiffies;
		return cfqd;
		}