From fe0714377ee2ca161bf2afb7773e22f15f1786d4 Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Fri, 1 Oct 2010 14:49:49 +0200 Subject: blkio: Recalculate the throttled bio dispatch time upon throttle limit change o Currently any cgroup throttle limit changes are processed asynchronousy and the change does not take affect till a new bio is dispatched from same group. o It might happen that a user sets a redicuously low limit on throttling. Say 1 bytes per second on reads. In such cases simple operations like mount a disk can wait for a very long time. o Once bio is throttled, there is no easy way to come out of that wait even if user increases the read limit later. o This patch fixes it. Now if a user changes the cgroup limits, we recalculate the bio dispatch time according to new limits. o Can't take queueu lock under blkcg_lock, hence after the change I wake up the dispatch thread again which recalculates the time. So there are some variables being synchronized across two threads without lock and I had to make use of barriers. Hoping I have used barriers correctly. Any review of memory barrier code especially will help. Signed-off-by: Vivek Goyal Signed-off-by: Jens Axboe --- block/blk-cgroup.h | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) (limited to 'block/blk-cgroup.h') diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index 2070053a30b..034c35562db 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -186,16 +186,17 @@ extern unsigned int blkcg_get_write_iops(struct blkio_cgroup *blkcg, dev_t dev); typedef void (blkio_unlink_group_fn) (void *key, struct blkio_group *blkg); -typedef void (blkio_update_group_weight_fn) (struct blkio_group *blkg, - unsigned int weight); -typedef void (blkio_update_group_read_bps_fn) (struct blkio_group *blkg, - u64 read_bps); -typedef void (blkio_update_group_write_bps_fn) (struct blkio_group *blkg, - u64 write_bps); -typedef void (blkio_update_group_read_iops_fn) (struct blkio_group *blkg, - unsigned int read_iops); -typedef void (blkio_update_group_write_iops_fn) (struct blkio_group *blkg, - unsigned int write_iops); + +typedef void (blkio_update_group_weight_fn) (void *key, + struct blkio_group *blkg, unsigned int weight); +typedef void (blkio_update_group_read_bps_fn) (void * key, + struct blkio_group *blkg, u64 read_bps); +typedef void (blkio_update_group_write_bps_fn) (void *key, + struct blkio_group *blkg, u64 write_bps); +typedef void (blkio_update_group_read_iops_fn) (void *key, + struct blkio_group *blkg, unsigned int read_iops); +typedef void (blkio_update_group_write_iops_fn) (void *key, + struct blkio_group *blkg, unsigned int write_iops); struct blkio_policy_ops { blkio_unlink_group_fn *blkio_unlink_group_fn; -- cgit v1.2.3-18-g5258