Messages in this thread | | | Date | Fri, 29 Apr 2016 13:21:12 -0700 (PDT) | From | Vikas Shivappa <> | Subject | Re: [PATCH 25/32] sched: introduce the finish_arch_pre_lock_switch() scheduler hook |
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On Fri, 29 Apr 2016, David Carrillo-Cisneros wrote:
> (Re-sending in plain text) > > This hook is used in the following patch in the series to write to > PQR_ASSOC_MSR, a msr that is utilized both by CQM/CMT and by CAT. > Since CAT is not dependent on perf, I created this hook to start CQM > monitoring right after other events start while keeping it independent > of perf. The idea is to have future versions of CAT to also rely on > this hook.
CAT did the msr write in switch_to as Peter did not want a new hook to be used. Same could be done here.
Thanks, Vikas
> > On Fri, Apr 29, 2016 at 11:05 AM, David Carrillo-Cisneros > <davidcc@google.com> wrote: >> This hook is used in the following patch in the series to write to >> PQR_ASSOC_MSR, a msr that is utilized both by CQM/CMT and by CAT. Since CAT >> is not dependent on perf, I created this hook to start CQM monitoring right >> after other events start while keeping it independent of perf. The idea is >> to have future versions of CAT to also rely on this hook. >> >> On Fri, Apr 29, 2016 at 1:52 AM Peter Zijlstra <peterz@infradead.org> wrote: >>> >>> On Thu, Apr 28, 2016 at 09:43:31PM -0700, David Carrillo-Cisneros wrote: >>>> This hook allows architecture specific code to be called at the end of >>>> the task switch and after perf_events' context switch but before the >>>> scheduler lock is released. >>>> >>>> The specific use case in this series is to avoid multiple writes to a >>>> slow >>>> MSR until all functions which modify such register in task switch have >>>> finished. >>> >>> Yeah, no. This really need way more justification. Why can't you use the >>> regular perf sched-in stuff for CQM? >
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