Messages in this thread | | | Subject | Re: [PATCH v2 6/8] sched/idle: Move busy_cpu accounting to idle callback | From | Aubrey Li <> | Date | Tue, 18 May 2021 14:05:56 +0800 |
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On 5/18/21 12:00 PM, Srikar Dronamraju wrote: > * Aubrey Li <aubrey.li@linux.intel.com> [2021-05-18 08:59:00]: > >> On 5/17/21 8:57 PM, Srikar Dronamraju wrote: >>> * Aubrey Li <aubrey.li@linux.intel.com> [2021-05-17 20:48:46]: >>> >>>> On 5/17/21 6:40 PM, Srikar Dronamraju wrote: >>>>> * Aubrey Li <aubrey.li@linux.intel.com> [2021-05-14 12:11:50]: >>>>> >>>>>> On 5/13/21 3:31 PM, Srikar Dronamraju wrote: >>>>>>> * Aubrey Li <aubrey.li@linux.intel.com> [2021-05-12 16:08:24]: >>>>>>>> On 5/7/21 12:45 AM, Srikar Dronamraju wrote: >>>>> >>>>> <snip> >>>>> >>>>>>>> Also, for those frequent context-switching tasks with very short idle, >>>>>>>> it's expensive for scheduler to mark idle/busy every time, that's why >>>>>>>> my patch only marks idle every time and marks busy ratelimited in >>>>>>>> scheduler tick. >>>>>>>> >>>>>>> >>>>>>> I have tried few tasks with very short idle times and updating nr_busy >>>>>>> everytime, doesnt seem to be impacting. Infact, it seems to help in picking >>>>>>> the idler-llc more often. >>>>>>> >>>>>> >>>>>> How many CPUs in your LLC? >>>>> >>>>> I have tried with X86, 48 CPUs, 2 nodes, each having 24 CPUs in LLC >>>>> + >>>>> POWER10, Multiple CPUs with 4 CPUs in LLC >>>>> + >>>>> POWER9, Multiple CPUs with 8 CPUs in LLC >>>>> >>>>>> >>>>>> This is a system with 192 CPUs, 4 nodes and each node has 48 CPUs in LLC >>>>>> domain. >>>>>> >>>>> >>>>> Okay, >>>>> >>>>>> It looks like for netperf both TCP and UDP cases have the notable change >>>>>> under 2 x overcommit, it may be not interesting though. >>>>>> >>>>>> >>>>> >>>>> I believe the extra load on this 24 core LLC could be because we may end up >>>>> trying to set the idle-core, even when there is no idle core available. >>>>> >>>>> If possible, can you please give a try with v3 with the call to >>>>> set_next_idle_core commented out? >>>>> >>>>> >>>> >>>> v3 seems not be applicable on tip/sched/core 915a2bc3c6b7? >>> >>> I had applied on top of 2ea46c6fc9452ac100ad907b051d797225847e33 >>> which was tag: sched-core-2021-04-28 >>> >>> The only conflict you get on today's tip is Gautham's one line patch. >>> Gautham's patch replaced 'this' with 'target'. >>> >>> The 2nd patch does away with that line >>> >> >> This is v3. It looks like hackbench gets better. And netperf still has >> some notable changes under 2 x overcommit cases. >> > > Thanks Aubrey for the results. netperf (2X) case does seem to regress. > I was actually expecting the results to get better with overcommit. > Can you confirm if this was just v3 or with v3 + set_next_idle_core > disabled?
Do you mean set_idle_cores(not set_next_idle_core) actually? Gautham's patch changed "this" to "target" in set_idle_cores, and I removed it to apply v3-2-8-sched-fair-Maintain-the-identity-of-idle-core.patch for tip/sched/core commit-id 915a2bc3c6b7.
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