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Re: [RFC][PATCH 5/5] sched/core: Add debug code to catch missing update_rq_clock()

From Yuyang Du <yuyang.du@intel.com>
Newsgroups linux.kernel
Subject Re: [RFC][PATCH 5/5] sched/core: Add debug code to catch missing update_rq_clock()
Date 2016-05-18 04:50 +0200
Message-ID <rzZIC-4vM-11@gated-at.bofh.it> (permalink)
References (1 earlier) <ry4W6-3UF-17@gated-at.bofh.it> <rzg8Z-u7-317@gated-at.bofh.it> <rznjX-5fy-3@gated-at.bofh.it> <rzEkN-7L0-1@gated-at.bofh.it> <rzMim-4v6-19@gated-at.bofh.it>
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On Tue, May 17, 2016 at 01:24:15PM +0100, Matt Fleming wrote:
> So, if the code looks like the following, either now or in the future,
> 
> static void __schedule(bool preempt)
> {
> 	...
> 	/* Clear RQCF_ACT_SKIP */
> 	rq->clock_update_flags = 0;
> 	...
> 	delta = rq_clock();
> }
 
Sigh, you even said "Clear RQCF_ACT_SKIP", but you not only clear it,
you clear everything. And if you clear the RQCF_UPDATE also (maybe you
shouldn't, but actually it does not matter), of course you will get
a warning...

In addition, it looks like multiple skips are possible, so:

update_rq_clock() {
        rq->clock_update_flags |= RQCF_UPDATE;

        ...
}

instead of clearing the skip flag there.

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Thread

[RFC][PATCH 5/5] sched/core: Add debug code to catch missing update_rq_clock() Matt Fleming <matt@codeblueprint.co.uk> - 2016-05-12 22:00 +0200
  Re: [RFC][PATCH 5/5] sched/core: Add debug code to catch missing  update_rq_clock() Yuyang Du <yuyang.du@intel.com> - 2016-05-16 04:10 +0200
    Re: [RFC][PATCH 5/5] sched/core: Add debug code to catch missing  update_rq_clock() Matt Fleming <matt@codeblueprint.co.uk> - 2016-05-16 11:50 +0200
      Re: [RFC][PATCH 5/5] sched/core: Add debug code to catch missing  update_rq_clock() Yuyang Du <yuyang.du@intel.com> - 2016-05-17 06:00 +0200
        Re: [RFC][PATCH 5/5] sched/core: Add debug code to catch missing  update_rq_clock() Matt Fleming <matt@codeblueprint.co.uk> - 2016-05-17 14:30 +0200
          Re: [RFC][PATCH 5/5] sched/core: Add debug code to catch missing  update_rq_clock() Yuyang Du <yuyang.du@intel.com> - 2016-05-18 04:50 +0200
            Re: [RFC][PATCH 5/5] sched/core: Add debug code to catch missing  update_rq_clock() Matt Fleming <matt@codeblueprint.co.uk> - 2016-05-18 10:50 +0200
              Re: [RFC][PATCH 5/5] sched/core: Add debug code to catch missing  update_rq_clock() Yuyang Du <yuyang.du@intel.com> - 2016-05-19 08:40 +0200

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