Re: [PATCH v4 07/10] perf tool_pmu: More accurately set the cpus for tool events

[Ian Rogers]

On Tue, Feb 3, 2026 at 3:27 PM Andres Freund <andres@xxxxxxxxxxx> wrote:
>
> Hi,
>
> On 2026-02-03 15:05:39 -0800, Ian Rogers wrote:
> > Thanks for the bug report! There were changes in v6.19 to change how
> > metrics were computed hence the fault in the metric computation. The
> > bisected patch is at fault, it aims to compute the CPU maps for tool
> > events in a way to avoid unnecessary sched setaffinity calls. By
> > having a smaller CPU map it set up a situation with user CPUs where
> > the tool events could have no CPUs, removed from the list of events
> > and the later seg fault occurred.
>
> Thanks for the quick reply!
>
> > I sent out a new patch series:
> > https://lore.kernel.org/linux-perf-users/20260203225129.4077140-1-irogers@xxxxxxxxxx/
> > that has a revert of this patch, a fix to correctly avoid the segfault in
> > the prepare_metric function, and a new patch to properly reduce the CPU maps
> > of the tool events. The remaining affinity reduction patches are still part
> > of the series and I believe ready to land.
>
> That sounds like it's targeted for 6.20?  I assume the revert on its own needs
> to land in 6.19 (or stable if too late for 6.19) somehow?

Yeah, the maintainers are the ones creating the pull requests and can do this.

Thanks,
Ian

> Greetings,
>
> Andres Freund