Messages in this thread Patch in this message | | | Subject | Re: [tip:sched/eevdf] [sched/fair] e0c2ff903c: phoronix-test-suite.blogbench.Write.final_score -34.8% regression | From | Mike Galbraith <> | Date | Mon, 14 Aug 2023 20:32:55 +0200 |
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On Mon, 2023-08-14 at 15:29 +0200, Peter Zijlstra wrote: > > --- > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index fe5be91c71c7..16d24e5dda8f 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -8047,6 +8047,15 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ > cfs_rq = cfs_rq_of(se); > update_curr(cfs_rq); > > + if (sched_feat(WAKEUP_DEADLINE)) { > + /* > + * Only allow preemption if the virtual deadline of the new > + * task is before the virtual deadline of the existing task. > + */ > + if (deadline_gt(deadline, pse, se)) > + return; > + } > + > /* > * XXX pick_eevdf(cfs_rq) != se ? > */ > diff --git a/kernel/sched/features.h b/kernel/sched/features.h > index 61bcbf5e46a4..e733981b32aa 100644 > --- a/kernel/sched/features.h > +++ b/kernel/sched/features.h > @@ -24,6 +24,7 @@ SCHED_FEAT(CACHE_HOT_BUDDY, true) > * Allow wakeup-time preemption of the current task: > */ > SCHED_FEAT(WAKEUP_PREEMPTION, true) > +SCHED_FEAT(WAKEUP_DEADLINE, true) > > SCHED_FEAT(HRTICK, false) > SCHED_FEAT(HRTICK_DL, false)
I don't have that phoronix thingy, but the above didn't seem to do anything for hackbench here.
I whack eevdf with the stick below to dampen its scheduling enthusiasm a little, and it did help the hackbench deficit some.
(yup, it's all rob Peter to pay Paul.. this game has no winner:)
hackbench -l 10000 avg 6.4.10-cfs 5.575 5.565 5.575 5.571 v cfs 6.4.10-eevdf 6.106 6.078 6.103 6.095 1.094 5.888 5.890 5.889 5.889 1.057 +RUN_TO_PARITY
--- kernel/sched/fair.c | 6 ++++++ kernel/sched/features.h | 1 + 2 files changed, 7 insertions(+)
--- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -875,6 +875,12 @@ static struct sched_entity *pick_eevdf(s if (curr && (!curr->on_rq || !entity_eligible(cfs_rq, curr))) curr = NULL; + /* + * Once selected, run the task to parity to avoid overscheduling. + */ + if (sched_feat(RUN_TO_PARITY) && curr) + return curr; + while (node) { struct sched_entity *se = __node_2_se(node); --- a/kernel/sched/features.h +++ b/kernel/sched/features.h @@ -7,6 +7,7 @@ SCHED_FEAT(PLACE_LAG, true) SCHED_FEAT(PLACE_FUDGE, true) SCHED_FEAT(PLACE_DEADLINE_INITIAL, true) +SCHED_FEAT(RUN_TO_PARITY, true) /* * Prefer to schedule the task we woke last (assuming it failed
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