Re: [linus:master] [sched/core] 118a2cf4ce: stress-ng.schedpolicy.ops_per_sec 14.1% regression

[Paul E. McKenney]

On Fri, Oct 23, 2026 at 07:00:23PM +0200, Peter Zijlstra wrote:
> On Fri, Oct 23, 2026 at 09:14:02AM -0700, Paul E. McKenney wrote:
> > On Fri, Oct 23, 2026 at 07:49:20PM +0800, kernel test robot wrote:
> > > 
> > > 
> > > Hello,
> > > 
> > > kernel test robot noticed a 14.1% regression of stress-ng.schedpolicy.ops_per_sec on:
> > > 
> > > 
> > > commit: 118a2cf4ced60777a2408001e2b4838fed1cea55 ("sched/core: Call wakeup_preempt() for queued tasks during class change") https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> > > 
> > > testcase: stress-ng
> > > config: x86_64-rhel-9.4
> > > compiler: gcc-14
> > > test machine: 224 threads 2 sockets Intel(R) Xeon(R) Platinum 8480CTDX (Sapphire Rapids) with 256G memory
> > > parameters:
> > > 
> > > 	nr_threads: 100%
> > > 	testtime: 60s
> > > 	test: schedpolicy
> > > 	cpufreq_governor: performance
> > > 
> > > 
> > > If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags
> > > | Reported-by: kernel test robot <yi1.lai@xxxxxxxxx>
> > > | Closes: https://lore.kernel.org/oe-lkp/202610231954.51716452-lkp@xxxxxxxxx
> > 
> > This regression is not a good thing, but this commit is fixing a real bug.
> 
> I think I have a patch somewhere stuck in my review queue for -rc1 that
> might help with this:
> 
>   https://patch.msgid.link/CANGjgdmNCfm%3DSctvKZ44y8b5n8t_JSp4meX%3DDKGnG74B3g1vVw%40mail.gmail.com

Here is hoping!

> If not, too bad, correctness first and all that.

Hear, hear!  ;-)

							Thanx, Paul