On Tue, 3 Mar 2020 at 00:13, Vishnu Rangayyan
<vishnu.rangayyan@xxxxxxxxx> wrote:
>
> Hi Sasha,
>
> Not sure of this, looks relevant but I'm no expert on this code.
> This particular change bef69dd87828 doesn't apply cleanly, need to
> backport it. I'll do that now and retest on the failing setup and report
> back.
>
> Best
> Vishnu
>
> On 2/29/20 7:11 PM, Sasha Levin wrote:
> > On Fri, Feb 28, 2020 at 12:13:54PM -0800, Vishnu Rangayyan wrote:
> >> Hi,
> >>
> >> I still see high (upto 30%) ksoftirqd cpu use with 4.19.101+ after
> >> these 2 back ports went in for 4.19.101
> >> (had all 4 backports applied earlier to our tree):
> >>
> >> commit f6783319737f28e4436a69611853a5a098cbe974 sched/fair: Fix
> >> insertion in rq->leaf_cfs_rq_list
> >> commit 5d299eabea5a251fbf66e8277704b874bbba92dc sched/fair: Add
> >> tmp_alone_branch assertion
> >>
> >> perf shows for any given ksoftirqd, with 20k-30k processes on the
> >> system with high scheduler load:
> >> 58.88% ksoftirqd/0 [kernel.kallsyms] [k] update_blocked_averages
> >>
> >> Can we backport these 2 also, confirmed that it fixes this behavior of
> >> ksoftirqd.
> >>
> >> commit 039ae8bcf7a5f4476f4487e6bf816885fb3fb617 upstream
> >> commit 31bc6aeaab1d1de8959b67edbed5c7a4b3cdbe7c upstream
> >
> > Do we also need bef69dd87828 ("sched/cpufreq: Move the
> > cfs_rq_util_change() call to cpufreq_update_util()") then?
This patch is not related to the 2 patches above. It removes some
spurious call to cfs_rq_util_change() and some wrong ordering but this
is a fixed overhead which is not impacted by the number of cgroups
unlike the 2 patches above. This patch will not help with the high
load of update_blocked_averages
> >
