diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2026-01-27 16:17:48 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-02-23 18:04:09 +0100 |
| commit | 9fe89f022c05d99c052d6bc088b82d4ff83bf463 (patch) | |
| tree | 3967b35e568221ab36e0617a86c6f5dbc5809c53 /kernel/sched/fair.c | |
| parent | 3b68df978133ac3d46d570af065a73debbb68248 (diff) | |
| download | linux-9fe89f022c05d99c052d6bc088b82d4ff83bf463.tar.gz linux-9fe89f022c05d99c052d6bc088b82d4ff83bf463.zip | |
sched/fair: More complex proportional newidle balance
It turns out that a few workloads (easyWave, fio) have a fairly low
success rate on newidle balance, but still benefit greatly from having
it anyway.
Luckliky these workloads have a faily low newidle rate, so the cost if
doing the newidle is relatively low, even if unsuccessfull.
Add a simple rate based part to the newidle ratio compute, such that
low rate newidle will still have a high newidle ratio.
This cures the easyWave and fio workloads while not affecting the
schbench numbers either (which have a very high newidle rate).
Reported-by: Mario Roy <marioeroy@gmail.com>
Reported-by: "Mohamed Abuelfotoh, Hazem" <abuehaze@amazon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Mario Roy <marioeroy@gmail.com>
Tested-by: "Mohamed Abuelfotoh, Hazem" <abuehaze@amazon.com>
Link: https://patch.msgid.link/20260127151748.GA1079264@noisy.programming.kicks-ass.net
Diffstat (limited to 'kernel/sched/fair.c')
| -rw-r--r-- | kernel/sched/fair.c | 27 |
1 files changed, 25 insertions, 2 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index bf948db905ed..66afa0ac7396 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -12289,7 +12289,30 @@ static inline void update_newidle_stats(struct sched_domain *sd, unsigned int su sd->newidle_success += success; if (sd->newidle_call >= 1024) { - sd->newidle_ratio = sd->newidle_success; + u64 now = sched_clock(); + s64 delta = now - sd->newidle_stamp; + sd->newidle_stamp = now; + int ratio = 0; + + if (delta < 0) + delta = 0; + + if (sched_feat(NI_RATE)) { + /* + * ratio delta freq + * + * 1024 - 4 s - 128 Hz + * 512 - 2 s - 256 Hz + * 256 - 1 s - 512 Hz + * 128 - .5 s - 1024 Hz + * 64 - .25 s - 2048 Hz + */ + ratio = delta >> 22; + } + + ratio += sd->newidle_success; + + sd->newidle_ratio = min(1024, ratio); sd->newidle_call /= 2; sd->newidle_success /= 2; } @@ -12996,7 +13019,7 @@ static int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf) if (sd->flags & SD_BALANCE_NEWIDLE) { unsigned int weight = 1; - if (sched_feat(NI_RANDOM)) { + if (sched_feat(NI_RANDOM) && sd->newidle_ratio < 1024) { /* * Throw a 1k sided dice; and only run * newidle_balance according to the success |