Messages in this thread |  | | Subject | Re: [patch 2/2] sched: fix nr_uninterruptible accounting of frozen tasks really | From | Peter Zijlstra <> | Date | Sat, 18 Jul 2009 14:56:31 +0200 |
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On Fri, 2009-07-17 at 15:55 -0500, Nathan Lynch wrote: > On Fri, 2009-07-17 at 18:47 +0200, Peter Zijlstra wrote: > > On Fri, 2009-07-17 at 08:22 -0700, Matt Helsley wrote: > > > > > The job scheduler in question does not use FROZEN as a transient state and > > > does not use checkpoint/restart at all since c/r is still a work in progress. > > Right, the job scheduler uses the cgroup freezer as a mechanism to > preempt a low priority job for a higher priority job. (It had used > SIGSTOP in the past.) So in this scenario a frozen cgroup may remain in > that state for a while. Load average is consulted as a measure of > system utilization.
I think that this is an utterly broken use for it, if you want something like that make a signal cgroup or something and deliver SIGSTOP to all of them.
In other words, why is the freezer any better than the SIGSTOP approach?
> > > Even when used for power management it seems wrong to count frozen tasks > > > towards the loadavg since they aren't using CPU time or waiting for IO. > > > > You're abusing it for _WHAT_? > > I think Matt was referring to system-wide suspend/resume/hibernate, not > a behavior of the job scheduler, if that's your concern.
I understood he referred to the crazy use-case you mentioned above, IMHO frozen should be a temporary state used for things like snapshot/migrate.
I'm still very tempted to plain simply revert that original patch.
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