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Commit 521f3bbd authored by Jens Axboe's avatar Jens Axboe
Browse files

io_context sharing - anticipatory changes 



changes to anticipatory io scheduler for io_context sharing

Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 4ac845a2

block/as-iosched.c

+28 −6
Original line number Diff line number Diff line
@@ -170,9 +170,11 @@ static void free_as_io_context(struct as_io_context *aic) 


static void as_trim(struct io_context *ioc)

{

	spin_lock(&ioc->lock);

	if (ioc->aic)

		free_as_io_context(ioc->aic);

	ioc->aic = NULL;

	spin_unlock(&ioc->lock);

}



/* Called when the task exits */
@@ -462,7 +464,9 @@ static void as_antic_timeout(unsigned long data) 
	spin_lock_irqsave(q->queue_lock, flags);

	if (ad->antic_status == ANTIC_WAIT_REQ

			|| ad->antic_status == ANTIC_WAIT_NEXT) {

		struct as_io_context *aic = ad->io_context->aic;

		struct as_io_context *aic;

		spin_lock(&ad->io_context->lock);

		aic = ad->io_context->aic;



		ad->antic_status = ANTIC_FINISHED;

		kblockd_schedule_work(&ad->antic_work);
@@ -475,6 +479,7 @@ static void as_antic_timeout(unsigned long data) 
			/* process not "saved" by a cooperating request */

			ad->exit_no_coop = (7*ad->exit_no_coop + 256)/8;

		}

		spin_unlock(&ad->io_context->lock);

	}

	spin_unlock_irqrestore(q->queue_lock, flags);

}
@@ -635,9 +640,11 @@ static int as_can_break_anticipation(struct as_data *ad, struct request *rq) 


	ioc = ad->io_context;

	BUG_ON(!ioc);

	spin_lock(&ioc->lock);



	if (rq && ioc == RQ_IOC(rq)) {

		/* request from same process */

		spin_unlock(&ioc->lock);

		return 1;

	}
@@ -646,20 +653,25 @@ static int as_can_break_anticipation(struct as_data *ad, struct request *rq) 
		 * In this situation status should really be FINISHED,

		 * however the timer hasn't had the chance to run yet.

		 */

		spin_unlock(&ioc->lock);

		return 1;

	}



	aic = ioc->aic;

	if (!aic)

	if (!aic) {

		spin_unlock(&ioc->lock);

		return 0;

	}



	if (atomic_read(&aic->nr_queued) > 0) {

		/* process has more requests queued */

		spin_unlock(&ioc->lock);

		return 1;

	}



	if (atomic_read(&aic->nr_dispatched) > 0) {

		/* process has more requests dispatched */

		spin_unlock(&ioc->lock);

		return 1;

	}
@@ -680,6 +692,7 @@ static int as_can_break_anticipation(struct as_data *ad, struct request *rq) 
		}



		as_update_iohist(ad, aic, rq);

		spin_unlock(&ioc->lock);

		return 1;

	}
@@ -688,20 +701,27 @@ static int as_can_break_anticipation(struct as_data *ad, struct request *rq) 
		if (aic->ttime_samples == 0)

			ad->exit_prob = (7*ad->exit_prob + 256)/8;



		if (ad->exit_no_coop > 128)

		if (ad->exit_no_coop > 128) {

			spin_unlock(&ioc->lock);

			return 1;

		}

	}



	if (aic->ttime_samples == 0) {

		if (ad->new_ttime_mean > ad->antic_expire)

		if (ad->new_ttime_mean > ad->antic_expire) {

			spin_unlock(&ioc->lock);

			return 1;

		if (ad->exit_prob * ad->exit_no_coop > 128*256)

		}

		if (ad->exit_prob * ad->exit_no_coop > 128*256) {

			spin_unlock(&ioc->lock);

			return 1;

		}

	} else if (aic->ttime_mean > ad->antic_expire) {

		/* the process thinks too much between requests */

		spin_unlock(&ioc->lock);

		return 1;

	}



	spin_unlock(&ioc->lock);

	return 0;

}
@@ -1255,7 +1275,9 @@ static void as_merged_requests(struct request_queue *q, struct request *req, 
			 * Don't copy here but swap, because when anext is

			 * removed below, it must contain the unused context

			 */

			double_spin_lock(&rioc->lock, &nioc->lock, rioc < nioc);

			swap_io_context(&rioc, &nioc);

			double_spin_unlock(&rioc->lock, &nioc->lock, rioc < nioc);

		}

	}