Re: [PATCH V4 02/15] blk-throttle: add .high interface

From	Tejun Heo <tj@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH V4 02/15] blk-throttle: add .high interface
Date	2016-11-23 22:20 +0100
Message-ID	<sGN7r-1Fi-15@gated-at.bofh.it> (permalink)
References	<sDxVf-4Bm-3@gated-at.bofh.it> <sDxVg-4Bm-53@gated-at.bofh.it> <sGpya-3s5-35@gated-at.bofh.it> <sGN7r-1Fi-17@gated-at.bofh.it>
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Hello,

On Tue, Nov 22, 2016 at 03:08:36PM -0800, Shaohua Li wrote:
> Yep, the limit could be high or max. It's doable moving the restrictions on
> input, but will increase trouble using the limits. If high is bigger than max,
> can I set high to max? if not, I'd prefer to keep the restrictions.

You can do that internally but userland should keep seeing what it
configured.

> > I haven't read the whole thing yet but this looks a bit suspicious.  A
> > css going offline indicates that the destruction of the css started.
> > I don't get why that'd reset high limits.  There can be a lot of async
> > IOs after offline.
> 
> Ok. We do want to reset the limits. Because if no cgroup has high limit, we
> definitively should use max limit for all cgroups. The whole state machine
> (switching between high and max limit) is meaningless in that case.
> 
> Is pd_free_fn a good place to guarantee anyc IOs finish?

Yeap.

Thanks.

-- 
tejun

Thread

[PATCH V4 00/15] blk-throttle: add .high limit Shaohua Li <shli@fb.com> - 2016-11-14 23:30 +0100
  [PATCH V4 09/15] blk-throttle: make bandwidth change smooth Shaohua Li <shli@fb.com> - 2016-11-14 23:30 +0100
    Re: [PATCH V4 09/15] blk-throttle: make bandwidth change smooth Tejun Heo <tj@kernel.org> - 2016-11-23 22:30 +0100
  [PATCH V4 11/15] blk-throttle: add interface to configure think time threshold Shaohua Li <shli@fb.com> - 2016-11-14 23:30 +0100
    Re: [PATCH V4 11/15] blk-throttle: add interface to configure think  time threshold Tejun Heo <tj@kernel.org> - 2016-11-23 22:40 +0100
  [PATCH V4 03/15] blk-throttle: configure bps/iops limit for cgroup in high limit Shaohua Li <shli@fb.com> - 2016-11-14 23:30 +0100
    Re: [PATCH V4 03/15] blk-throttle: configure bps/iops limit for  cgroup in high limit Tejun Heo <tj@kernel.org> - 2016-11-22 21:20 +0100
  [PATCH V4 01/15] blk-throttle: prepare support multiple limits Shaohua Li <shli@fb.com> - 2016-11-14 23:30 +0100
  [PATCH V4 15/15] blk-throttle: add latency target support Shaohua Li <shli@fb.com> - 2016-11-14 23:30 +0100
  [PATCH V4 13/15] blk-throttle: add a mechanism to estimate IO latency Shaohua Li <shli@fb.com> - 2016-11-14 23:30 +0100
  [PATCH V4 02/15] blk-throttle: add .high interface Shaohua Li <shli@fb.com> - 2016-11-14 23:30 +0100
    Re: [PATCH V4 02/15] blk-throttle: add .high interface Tejun Heo <tj@kernel.org> - 2016-11-22 21:10 +0100
      Re: [PATCH V4 02/15] blk-throttle: add .high interface Tejun Heo <tj@kernel.org> - 2016-11-23 22:20 +0100
  [PATCH V4 08/15] blk-throttle: detect completed idle cgroup Shaohua Li <shli@fb.com> - 2016-11-14 23:30 +0100

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