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Commit e4313dd4 authored by Jens Axboe's avatar Jens Axboe Committed by Jens Axboe
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[PATCH] as-iosched: use new io context counting mechanism 



It's ok if the read path is a lot more costly, as long as inc/dec is
really cheap. The inc/dec will happen for each created/freed io context,
while the reading only happens when a disk queue exits.

Signed-off-by: default avatarJens Axboe <axboe@suse.de>
parent 4a893e83

block/as-iosched.c

+5 −4
Original line number Diff line number Diff line
@@ -149,7 +149,7 @@ enum arq_state { 
#define RQ_STATE(rq)	((enum arq_state)(rq)->elevator_private2)

#define RQ_SET_STATE(rq, state)	((rq)->elevator_private2 = (void *) state)



static atomic_t ioc_count = ATOMIC_INIT(0);

static DEFINE_PER_CPU(unsigned long, ioc_count);

static struct completion *ioc_gone;



static void as_move_to_dispatch(struct as_data *ad, struct request *rq);
@@ -163,7 +163,8 @@ static void as_antic_stop(struct as_data *ad); 
static void free_as_io_context(struct as_io_context *aic)

{

	kfree(aic);

	if (atomic_dec_and_test(&ioc_count) && ioc_gone)

	elv_ioc_count_dec(ioc_count);

	if (ioc_gone && !elv_ioc_count_read(ioc_count))

		complete(ioc_gone);

}
@@ -199,7 +200,7 @@ static struct as_io_context *alloc_as_io_context(void) 
		ret->seek_total = 0;

		ret->seek_samples = 0;

		ret->seek_mean = 0;

		atomic_inc(&ioc_count);

		elv_ioc_count_inc(ioc_count);

	}



	return ret;
@@ -1484,7 +1485,7 @@ static void __exit as_exit(void) 
	ioc_gone = &all_gone;

	/* ioc_gone's update must be visible before reading ioc_count */

	smp_wmb();

	if (atomic_read(&ioc_count))

	if (elv_ioc_count_read(ioc_count))

		wait_for_completion(ioc_gone);

	synchronize_rcu();

}