* Al Boldi <a1426z@xxxxxxxxx> wrote:
ok. I think i might finally have found the bug causing this. Could you try the fix below, does your webserver thread-startup test work any better?It seems to help somewhat, but the problem is still visible. Even v20.3 on 2.6.22.5 didn't help.
It does look related to ia-boosting, so I turned off __update_curr like Roman mentioned, which had an enormous smoothing effect, but then nice levels completely break down and lockup the system.
you can turn sleeper-fairness off via:
echo 28 > /proc/sys/kernel/sched_features
another thing to try would be:
echo 12 > /proc/sys/kernel/sched_features
(that's the new-task penalty turned off.)
Another thing to try would be to edit this:
if (sysctl_sched_features & SCHED_FEAT_START_DEBIT)
p->se.wait_runtime = -(sched_granularity(cfs_rq) / 2);
to:
if (sysctl_sched_features & SCHED_FEAT_START_DEBIT)
p->se.wait_runtime = -(sched_granularity(cfs_rq);
and could you also check 20.4 on 2.6.22.5 perhaps, or very latest -git? (Peter has experienced smaller spikes with that.)
Ingo