Re: [PATCH] perf/x86: Add cond_resched() when allocate/release DS buffers

[Peter Zijlstra]

On Tue, Oct 28, 2025 at 12:02:58PM -0700, Namhyung Kim wrote:
> Hi Peter,
> 
> On Tue, Oct 28, 2025 at 04:27:47PM +0100, Peter Zijlstra wrote:
> > On Tue, Oct 28, 2025 at 03:15:18PM +0100, Peter Zijlstra wrote:
> > > On Mon, Oct 27, 2025 at 02:27:24PM -0700, Namhyung Kim wrote:
> > > > On large systems, it's possible to trigger sched latency warning during
> > > > the DS buffer allocation or release.  Add cond_resched() to avoid it.
> > > 
> > > We're >.< close to deleting cond_resched(), it makes absolutely no sense
> > > adding more.
> > 
> > Specifically, IIRC the plan was to do something like the below after the
> > next LTS release, and then continue to remove VOLUNTARY in subsequent
> > releases, leaving NONE the only option for the legacy architectures that
> > do not support preemption.
> 
> Thanks for your review!
> 
> I haven't followed the work in this area so was not aware of the
> PREEMPT_LAZY.  Looks great!  I hope it'll work well on server platforms
> with many batch jobs and interactive tasks.
> 
> I will drop my patch then.

Well, we've been trying to get people to test things... But
realistically people will only test once you force them. So we'll see.