On Sun, Jul 05, 2026 at 10:04:50PM +0200, Thomas Gleixner wrote:
> On Fri, Jul 03 2026 at 11:21, Feng Tang wrote:
> > When running mixed stress tests (stess-ng, kernel selftests etc.)
> > on a slow machine, futex 'requeue_multiple' case failed randomly,
> > with message:
> > "
> > waiter failed errno 110
> > not ok 2 futex_requeue many returned: 0 Success
> > not ok 3 futex_requeue many returned: 0 Success
> > # Planned tests != run tests (2 != 3)
> > # Totals: pass:1 fail:2 xfail:0 xpass:0 skip:0 error:0
> > "
> >
> > The process of 'requeue_multiple' case will:
> > * create 10 pthreads with futex (timeout 30 ms)
> > * wait 10 ms
> > * start 'futex_cmp_requeue' case
> >
> > So there is an assumption that the 10 threads can be created in 20 ms,
> > which is safe enough for normal platforms, while for slow platforms
> > with stress workload, the creation could take more than 20 ms, and
> > some futex will timeout and cause the case to fail.
> >
> > Increasing the timeout to 100 ms to cover slow platforms, which doesn't
> > hurt normal platforms much.
>
> That's just lame and it hurts because it makes testing slower. If you'd
> had taken the time to search LKML for discusssions about this issue then
> you'd have noticed that there is work in progress to solve that
> properly.
>
>
> https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?h=locking/futex&id=157a9b22ff769e1a657aec6210df3ea896600eec
Thanks for the link!
Good to see it merged. Just tried the latest tip tree, and 'futex_requeue'
did pass on our slow platform. (the timeout is now 2 seconds, which should
cover it well).
I know 157a9b22ff76 ("selftests/futex: Use thread synchronization helpers
instead of usleep() ")
was merged, but FWIW:
Tested-by: Feng Tang <[email protected]>
Thanks,
Feng
