[PATCH 29/51] writeback, blkcg: propagate non-root blkcg congestion state
From: Tejun Heo <tj@kernel.org>
Date: 2015-05-22 21:13:43
Also in:
linux-fsdevel, linux-mm, lkml
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
Now that bdi layer can handle per-blkcg bdi_writeback_congested state,
blk_{set|clear}_congested() can propagate non-root blkcg congestion
state to them.
This can be easily achieved by disabling the root_rl tests in
blk_{set|clear}_congested(). Note that we still need those tests when
!CONFIG_CGROUP_WRITEBACK as otherwise we'll end up flipping root blkcg
wb's congestion state for events happening on other blkcgs.
v2: Updated for bdi_writeback_congested.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Vivek Goyal <vgoyal@redhat.com>
---
block/blk-core.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index b457c4f..cf6974e 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c@@ -65,23 +65,26 @@ static struct workqueue_struct *kblockd_workqueue; static void blk_clear_congested(struct request_list *rl, int sync) { - if (rl != &rl->q->root_rl) - return; #ifdef CONFIG_CGROUP_WRITEBACK clear_wb_congested(rl->blkg->wb_congested, sync); #else - clear_wb_congested(rl->q->backing_dev_info.wb.congested, sync); + /* + * If !CGROUP_WRITEBACK, all blkg's map to bdi->wb and we shouldn't + * flip its congestion state for events on other blkcgs. + */ + if (rl == &rl->q->root_rl) + clear_wb_congested(rl->q->backing_dev_info.wb.congested, sync); #endif } static void blk_set_congested(struct request_list *rl, int sync) { - if (rl != &rl->q->root_rl) - return; #ifdef CONFIG_CGROUP_WRITEBACK set_wb_congested(rl->blkg->wb_congested, sync); #else - set_wb_congested(rl->q->backing_dev_info.wb.congested, sync); + /* see blk_clear_congested() */ + if (rl == &rl->q->root_rl) + set_wb_congested(rl->q->backing_dev_info.wb.congested, sync); #endif }
--
2.4.0
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