cfq: merge cooperating cfq_queues (df5fe3e8) · Commits · 戴 / test

block/cfq-iosched.c

+87 −2

Original line number	Diff line number	Diff line
		@@ -118,6 +118,8 @@ struct cfq_queue {
		sector_t last_request_pos;

		pid_t pid;

		struct cfq_queue *new_cfqq;
		};

		/*
		@@ -1047,6 +1049,12 @@ static struct cfq_queue cfq_close_cooperator(struct cfq_data cfqd,
		if (!cfqq)
		return NULL;

		/*
		* It only makes sense to merge sync queues.
		*/
		if (!cfq_cfqq_sync(cfqq))
		return NULL;

		if (cfq_cfqq_coop(cfqq))
		return NULL;

		@@ -1167,6 +1175,43 @@ cfq_prio_to_maxrq(struct cfq_data cfqd, struct cfq_queue cfqq)
		return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
		}

		/*
		* Must be called with the queue_lock held.
		*/
		static int cfqq_process_refs(struct cfq_queue *cfqq)
		{
		int process_refs, io_refs;

		io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
		process_refs = atomic_read(&cfqq->ref) - io_refs;
		BUG_ON(process_refs < 0);
		return process_refs;
		}

		static void cfq_setup_merge(struct cfq_queue cfqq, struct cfq_queue new_cfqq)
		{
		int process_refs;
		struct cfq_queue *__cfqq;

		/* Avoid a circular list and skip interim queue merges */
		while ((__cfqq = new_cfqq->new_cfqq)) {
		if (__cfqq == cfqq)
		return;
		new_cfqq = __cfqq;
		}

		process_refs = cfqq_process_refs(cfqq);
		/*
		* If the process for the cfqq has gone away, there is no
		* sense in merging the queues.
		*/
		if (process_refs == 0)
		return;

		cfqq->new_cfqq = new_cfqq;
		atomic_add(process_refs, &new_cfqq->ref);
		}

		/*
		* Select a queue for service. If we have a current active queue,
		* check whether to continue servicing it, or retrieve and set a new one.
		@@ -1196,11 +1241,14 @@ static struct cfq_queue cfq_select_queue(struct cfq_data cfqd)
		* If another queue has a request waiting within our mean seek
		* distance, let it run. The expire code will check for close
		* cooperators and put the close queue at the front of the service
		* tree.
		* tree. If possible, merge the expiring queue with the new cfqq.
		*/
		new_cfqq = cfq_close_cooperator(cfqd, cfqq, 0);
		if (new_cfqq)
		if (new_cfqq) {
		if (!cfqq->new_cfqq)
		cfq_setup_merge(cfqq, new_cfqq);
		goto expire;
		}

		/*
		* No requests pending. If the active queue still has requests in
		@@ -1511,11 +1559,29 @@ static void cfq_free_io_context(struct io_context *ioc)

		static void cfq_exit_cfqq(struct cfq_data cfqd, struct cfq_queue cfqq)
		{
		struct cfq_queue __cfqq, next;

		if (unlikely(cfqq == cfqd->active_queue)) {
		__cfq_slice_expired(cfqd, cfqq, 0);
		cfq_schedule_dispatch(cfqd);
		}

		/*
		* If this queue was scheduled to merge with another queue, be
		* sure to drop the reference taken on that queue (and others in
		* the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
		*/
		__cfqq = cfqq->new_cfqq;
		while (__cfqq) {
		if (__cfqq == cfqq) {
		WARN(1, "cfqq->new_cfqq loop detected\n");
		break;
		}
		next = __cfqq->new_cfqq;
		cfq_put_queue(__cfqq);
		__cfqq = next;
		}

		cfq_put_queue(cfqq);
		}

		@@ -2323,6 +2389,16 @@ static void cfq_put_request(struct request *rq)
		}
		}

		static struct cfq_queue *
		cfq_merge_cfqqs(struct cfq_data cfqd, struct cfq_io_context cic,
		struct cfq_queue *cfqq)
		{
		cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
		cic_set_cfqq(cic, cfqq->new_cfqq, 1);
		cfq_put_queue(cfqq);
		return cic_to_cfqq(cic, 1);
		}

		/*
		* Allocate cfq data structures associated with this request.
		*/
		@@ -2349,6 +2425,15 @@ cfq_set_request(struct request_queue q, struct request rq, gfp_t gfp_mask)
		if (!cfqq \|\| cfqq == &cfqd->oom_cfqq) {
		cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
		cic_set_cfqq(cic, cfqq, is_sync);
		} else {
		/*
		* Check to see if this queue is scheduled to merge with
		* another, closely cooperating queue. The merging of
		* queues happens here as it must be done in process context.
		* The reference on new_cfqq was taken in merge_cfqqs.
		*/
		if (cfqq->new_cfqq)
		cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
		}

		cfqq->allocated[rw]++;

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