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| author |   Juri Lelli <juri.lelli@redhat.com> | 2025-07-21 15:01:42 +0200 |
|---|---|---|
| committer |   Peter Zijlstra <peterz@infradead.org> | 2025-08-26 10:46:00 +0200 |
| commit | bb4700adc3abec34c0a38b64f66258e4e233fc16 (patch) | |
| tree | 6ec76b3348748cc686ff980537022a7b1c6ff7cf | |
| parent | sched/deadline: Fix dl_server_stopped() (diff) | |
| download | wireguard-linux-bb4700adc3abec34c0a38b64f66258e4e233fc16.tar.xz wireguard-linux-bb4700adc3abec34c0a38b64f66258e4e233fc16.zip | |
sched/deadline: Always stop dl-server before changing parameters
Commit cccb45d7c4295 ("sched/deadline: Less agressive dl_server
handling") reduced dl-server overhead by delaying disabling servers only
after there are no fair task around for a whole period, which means that
deadline entities are not dequeued right away on a server stop event.
However, the delay opens up a window in which a request for changing
server parameters can break per-runqueue running_bw tracking, as
reported by Yuri.
Close the problematic window by unconditionally calling dl_server_stop()
before applying the new parameters (ensuring deadline entities go
through an actual dequeue).
Fixes: cccb45d7c4295 ("sched/deadline: Less agressive dl_server handling")
Reported-by: Yuri Andriaccio <yurand2000@gmail.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20250721-upstream-fix-dlserver-lessaggressive-b4-v1-1-4ebc10c87e40@redhat.com
| -rw-r--r-- | kernel/sched/debug.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 3f06ab84d53f..02e16b70a790 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -376,10 +376,8 @@ static ssize_t sched_fair_server_write(struct file *filp, const char __user *ubu return -EINVAL; } - if (rq->cfs.h_nr_queued) { - update_rq_clock(rq); - dl_server_stop(&rq->fair_server); - } + update_rq_clock(rq); + dl_server_stop(&rq->fair_server); retval = dl_server_apply_params(&rq->fair_server, runtime, period, 0); if (retval) |