Re: [REGRESSION] 6.12.y: d66792919d4f (sched/deadline: Use revised wakeup rule for dl_server) causes latencies up to 50ms with PREEMPT_RT
Mike Galbraith <[email protected]> Mon, 11 May 2026 17:30:01 +0200
| Newsgroups | org.kernel.vger.linux-rt-users,dev.linux.lists.regressions,org.kernel.vger.stable |
|---|---|
| Message-ID | <[email protected]> |
On Mon, 2026-05-11 at 10:21 -0400, Sasha Levin wrote:
>
> Mike's reply notes that his local 6.12-rt tree carrying the following
> three commits in cannot reproduce, while the same tree without them
> reproduces quickly:
>
> cccb45d7c429 ("sched/deadline: Less agressive dl_server handling")
> 4ae8d9aa9f9d ("sched/deadline: Fix dl_server getting stuck")
> a3a70caf7906 ("sched/deadline: Fix dl_server behaviour")
>
> d66792919d4f's upstream commit message explicitly says it relies on the
> state established by a3a70caf7906, and none of the three are in 6.12.y.
>
> Could you give those three commits a spin on top of 6.12.y (keeping
> d66792919d4f in place) and see whether the latency goes away?
I've meanwhile tried those three alone, and the size XXL hits my box
readily reproduces in virgin source do indeed go away.
'course there may be another shoe, so...
-Mike