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From: Tejun Heo <tj@kernel.org>
To: Shaohua Li <shli@fb.com>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	Kernel-team@fb.com, axboe@fb.com, vgoyal@redhat.com
Subject: Re: [PATCH V4 07/15] blk-throttle: make throtl_slice tunable
Date: Wed, 23 Nov 2016 16:17:02 -0500	[thread overview]
Message-ID: <20161123211702.GB11306@mtj.duckdns.org> (raw)
In-Reply-To: <20161122231824.GC14628@shli-mbp.local>

Hello,

On Tue, Nov 22, 2016 at 03:18:24PM -0800, Shaohua Li wrote:
> Hmm, it's not a real 'time slice'. The name is a bit confusion. Maybe rename it
> to 'throtl_interval' or 'throtl_sampling_time'? not sure. bandwidth and iops
> are always in terms of a time interval we measure them. We can't say the
> iops/bw for a single io. So this is really a tuable knob.

Yeah, maybe using a more indicative name is better.  However, even if
we say that this is the sampling period, it's not clear how adjusting
the knob would affect the behavior as that's not something clearly
defined in blk-throtl's operation model.  For contrast, compare it
with the latency target, the implemented behavior might not succeed to
follow the intended configuration perfectly but what the intention of
the configuration is clear regardless.

That said, if this needs to be a tunable knob, it's fine to have it,
but let's at least try to document what the effects of changing the
variable is.

Thanks.

-- 
tejun

  reply	other threads:[~2016-11-23 21:17 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-14 22:22 [PATCH V4 00/15] blk-throttle: add .high limit Shaohua Li
2016-11-14 22:22 ` [PATCH V4 01/15] blk-throttle: prepare support multiple limits Shaohua Li
2016-11-14 22:22 ` [PATCH V4 02/15] blk-throttle: add .high interface Shaohua Li
2016-11-22 20:02   ` Tejun Heo
2016-11-22 23:08     ` Shaohua Li
2016-11-23 21:11       ` Tejun Heo
2016-11-14 22:22 ` [PATCH V4 03/15] blk-throttle: configure bps/iops limit for cgroup in high limit Shaohua Li
2016-11-22 20:16   ` Tejun Heo
2016-11-22 23:11     ` Shaohua Li
2016-11-14 22:22 ` [PATCH V4 04/15] blk-throttle: add upgrade logic for LIMIT_HIGH state Shaohua Li
2016-11-14 22:22 ` [PATCH V4 05/15] blk-throttle: add downgrade logic Shaohua Li
2016-11-22 21:21   ` Tejun Heo
2016-11-22 21:42     ` Tejun Heo
2016-11-22 23:38       ` Shaohua Li
2016-11-14 22:22 ` [PATCH V4 06/15] blk-throttle: make sure expire time isn't too big Shaohua Li
2016-11-14 22:22 ` [PATCH V4 07/15] blk-throttle: make throtl_slice tunable Shaohua Li
2016-11-22 21:27   ` Tejun Heo
2016-11-22 23:18     ` Shaohua Li
2016-11-23 21:17       ` Tejun Heo [this message]
2016-11-14 22:22 ` [PATCH V4 08/15] blk-throttle: detect completed idle cgroup Shaohua Li
2016-11-14 22:22 ` [PATCH V4 09/15] blk-throttle: make bandwidth change smooth Shaohua Li
2016-11-23 21:23   ` Tejun Heo
2016-11-24  0:59     ` Shaohua Li
2016-11-14 22:22 ` [PATCH V4 10/15] blk-throttle: add a simple idle detection Shaohua Li
2016-11-23 21:46   ` Tejun Heo
2016-11-24  1:15     ` Shaohua Li
2016-11-28 22:21       ` Tejun Heo
2016-11-28 23:10         ` Shaohua Li
2016-11-29 17:08           ` Tejun Heo
2016-11-14 22:22 ` [PATCH V4 11/15] blk-throttle: add interface to configure think time threshold Shaohua Li
2016-11-23 21:32   ` Tejun Heo
2016-11-24  1:06     ` Shaohua Li
2016-11-28 22:08       ` Tejun Heo
2016-11-28 22:14         ` Shaohua Li
2016-11-14 22:22 ` [PATCH V4 12/15] blk-throttle: ignore idle cgroup limit Shaohua Li
2016-11-14 22:22 ` [PATCH V4 13/15] blk-throttle: add a mechanism to estimate IO latency Shaohua Li
2016-11-14 23:40   ` kbuild test robot
2016-11-15  3:57   ` kbuild test robot
2016-11-29 17:24   ` Tejun Heo
2016-11-29 18:30     ` Shaohua Li
2016-11-29 22:36       ` Tejun Heo
2016-11-14 22:22 ` [PATCH V4 14/15] blk-throttle: add interface for per-cgroup target latency Shaohua Li
2016-11-14 22:22 ` [PATCH V4 15/15] blk-throttle: add latency target support Shaohua Li
2016-11-29 17:31   ` Tejun Heo
2016-11-29 18:14     ` Shaohua Li
2016-11-29 22:54       ` Tejun Heo
2016-11-29 23:39         ` Shaohua Li
2016-11-14 22:46 ` [PATCH V4 00/15] blk-throttle: add .high limit Bart Van Assche
2016-11-15  0:05   ` Shaohua Li
2016-11-15  0:41     ` Bart Van Assche
2016-11-15  0:49       ` Shaohua Li
2016-11-15  1:18         ` Bart Van Assche
2016-11-15  1:28           ` Shaohua Li
2016-11-15 19:53             ` Bart Van Assche
2016-11-15 21:31               ` Shaohua Li

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