On Fri 22-05-15 17:13:43, Tejun Heo wrote:
> 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.
Looks good. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxxx>
Honza
>
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Jens Axboe <axboe@xxxxxxxxx>
> Cc: Jan Kara <jack@xxxxxxx>
> Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
> ---
> 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
>
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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