On Sat, 2009-07-18 at 14:56 +0200, Peter Zijlstra wrote: > 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? Documentation/cgroups/freezer-subsystem.txt happens to document this use case and the disadvantages of SIGSTOP/SIGCONT. Does that change your opinion at all? > > > > 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. But snapshot (or checkpoint) and migration aren't possible with mainline at this time. As far as I know, the use case to which you object is the primary use of the cgroup freezer on production systems. _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
