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From: Dennis Zhou <dennisszhou@gmail.com>
To: Josef Bacik <josef@toxicpanda.com>
Cc: Jens Axboe <axboe@kernel.dk>, Tejun Heo <tj@kernel.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	kernel-team@fb.com, linux-block@vger.kernel.org,
	cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
	Jiufei Xue <jiufei.xue@linux.alibaba.com>,
	Joseph Qi <joseph.qi@linux.alibaba.com>
Subject: Re: [PATCH 03/15] blkcg: use tryget logic when associating a blkg with a bio
Date: Fri, 31 Aug 2018 16:20:40 -0400
Message-ID: <20180831202040.GB20194@dennisz-mbp.dhcp.thefacebook.com> (raw)
In-Reply-To: <20180831153007.nybnuyx43adn76rm@destiny>

Hi Josef,

On Fri, Aug 31, 2018 at 11:30:08AM -0400, Josef Bacik wrote:
> On Thu, Aug 30, 2018 at 09:53:44PM -0400, Dennis Zhou wrote:
> > diff --git a/block/blk-throttle.c b/block/blk-throttle.c
> > index a3eede00d302..c626e1f7cdcd 100644
> > --- a/block/blk-throttle.c
> > +++ b/block/blk-throttle.c
> > @@ -2129,8 +2129,9 @@ static inline void throtl_update_latency_buckets(struct throtl_data *td)
> >  static void blk_throtl_assoc_bio(struct throtl_grp *tg, struct bio *bio)
> >  {
> >  #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
> > -	if (bio->bi_css)
> > -		bio_associate_blkg(bio, tg_to_blkg(tg));
> > +	/* fallback to root_blkg if we fail to get a blkg ref */
> > +	if (bio->bi_css && bio_associate_blkg(bio, tg_to_blkg(tg)))
> > +		bio_associate_blkg(bio, bio->bi_disk->queue->root_blkg);
> 
> Except if we've already assocated a blkg this is just extra, can we do
> 
> if (bio->bi_css && (bio_associate_blkg(bio, tg_to_blkg(tg)) == -ENODEV))
> 
> to make it clear that we're only attaching it to the root if we failed to attach
> a blkg at all?  Thanks,

Done in v2.

Thanks,
Dennis

  reply index

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-31  1:53 [PATCH 00/15] blkcg ref count refactor/cleanup + blkcg avg_lat Dennis Zhou
2018-08-31  1:53 ` [PATCH 01/15] Revert "blk-throttle: fix race between blkcg_bio_issue_check() and cgroup_rmdir()" Dennis Zhou
2018-08-31  1:53 ` [PATCH 02/15] blkcg: delay blkg destruction until after writeback has finished Dennis Zhou
2018-08-31 15:27   ` Josef Bacik
2018-08-31 20:19     ` Dennis Zhou
2018-08-31  1:53 ` [PATCH 03/15] blkcg: use tryget logic when associating a blkg with a bio Dennis Zhou
2018-08-31 15:30   ` Josef Bacik
2018-08-31 20:20     ` Dennis Zhou [this message]
2018-08-31  1:53 ` [PATCH 04/15] blkcg: fix ref count issue with bio_blkcg using task_css Dennis Zhou
2018-08-31 15:35   ` Josef Bacik
2018-08-31 23:04     ` Tejun Heo
2018-09-06 15:21     ` Dennis Zhou
2018-08-31  1:53 ` [PATCH 05/15] blkcg: update blkg_lookup_create to do locking Dennis Zhou
2018-08-31 15:37   ` Josef Bacik
2018-08-31 23:09   ` Tejun Heo
2018-08-31  1:53 ` [PATCH 06/15] blkcg: always associate a bio with a blkg Dennis Zhou
2018-08-31  9:01   ` kbuild test robot
2018-08-31 10:02   ` kbuild test robot
2018-08-31 23:16   ` Tejun Heo
2018-09-06 20:41     ` Dennis Zhou
2018-09-07  3:03   ` [LKP] [blkcg] c02c58dab2: WARNING:at_block/blk-throttle.c:#blk_throtl_bio kernel test robot
2018-08-31  1:53 ` [PATCH 07/15] blkcg: consolidate bio_issue_init and blkg association Dennis Zhou
2018-08-31  9:19   ` kbuild test robot
2018-08-31 11:11   ` kbuild test robot
2018-08-31 15:42   ` Josef Bacik
2018-09-06 20:43     ` Dennis Zhou
2018-08-31 23:45   ` Tejun Heo
2018-08-31  1:53 ` [PATCH 08/15] blkcg: associate a blkg for pages being evicted by swap Dennis Zhou
2018-08-31 15:44   ` Josef Bacik
2018-08-31 23:47   ` Tejun Heo
2018-08-31  1:53 ` [PATCH 09/15] blkcg: associate writeback bios with a blkg Dennis Zhou
2018-08-31 15:45   ` Josef Bacik
2018-08-31 23:53   ` Tejun Heo
2018-08-31  1:53 ` [PATCH 10/15] blkcg: remove bio->bi_css and instead use bio->bi_blkg Dennis Zhou
2018-08-31 15:46   ` Josef Bacik
2018-09-01  0:13   ` Tejun Heo
2018-08-31  1:53 ` [PATCH 11/15] blkcg: remove additional reference to the css Dennis Zhou
2018-09-01  0:26   ` Tejun Heo
2018-09-06 20:45     ` Dennis Zhou
2018-08-31  1:53 ` [PATCH 12/15] blkcg: cleanup and make blk_get_rl use blkg_lookup_create Dennis Zhou
2018-09-01  0:29   ` Tejun Heo
2018-09-11  2:37   ` [LKP] [blkcg] 22f657e287: general_protection_fault:#[##] kernel test robot
2018-08-31  1:53 ` [PATCH 13/15] blkcg: change blkg reference counting to use percpu_ref Dennis Zhou
2018-08-31 15:49   ` Josef Bacik
2018-09-01  0:31   ` Tejun Heo
2018-09-06 20:46     ` Dennis Zhou
2018-09-07  3:08   ` [LKP] [blkcg] 6ef69a3a0b: WARNING:suspicious_RCU_usage kernel test robot
2018-08-31  1:53 ` [PATCH 14/15] blkcg: rename blkg_try_get to blkg_tryget Dennis Zhou
2018-08-31 15:50   ` Josef Bacik
2018-09-01  0:32   ` Tejun Heo
2018-08-31  1:53 ` [PATCH 15/15] blkcg: add average latency tracking to blk-cgroup Dennis Zhou
2018-08-31 10:22   ` kbuild test robot
2018-08-31 11:38   ` kbuild test robot
2018-09-01  0:35 ` [PATCH 00/15] blkcg ref count refactor/cleanup + blkcg avg_lat Tejun Heo

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