diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2025-11-07 17:01:20 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2025-11-17 17:13:15 +0100 |
| commit | d206fbad9328ddb68ebabd7cf7413392acd38081 (patch) | |
| tree | 39de971309d0f5bf9ffc34ba5e6d03d5d03b8f15 | |
| parent | e837456fdca81899a3c8e47b3fd39e30eae6e291 (diff) | |
sched/fair: Revert max_newidle_lb_cost bump
Many people reported regressions on their database workloads due to:
155213a2aed4 ("sched/fair: Bump sd->max_newidle_lb_cost when newidle balance fails")
For instance Adam Li reported a 6% regression on SpecJBB.
Conversely this will regress schbench again; on my machine from 2.22
Mrps/s down to 2.04 Mrps/s.
Reported-by: Joseph Salisbury <joseph.salisbury@oracle.com>
Reported-by: Adam Li <adamli@os.amperecomputing.com>
Reported-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reported-by: Hazem Mohamed Abuelfotoh <abuehaze@amazon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Chris Mason <clm@meta.com>
Link: https://lkml.kernel.org/r/20250626144017.1510594-2-clm@fb.com
Link: https://lkml.kernel.org/r/006c9df2-b691-47f1-82e6-e233c3f91faf@oracle.com
Link: https://patch.msgid.link/20251107161739.406147760@infradead.org
| -rw-r--r-- | kernel/sched/fair.c | 19 |
1 files changed, 3 insertions, 16 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index c6e5c64dd332..b73af3783de4 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -12230,14 +12230,8 @@ static inline bool update_newidle_cost(struct sched_domain *sd, u64 cost) /* * Track max cost of a domain to make sure to not delay the * next wakeup on the CPU. - * - * sched_balance_newidle() bumps the cost whenever newidle - * balance fails, and we don't want things to grow out of - * control. Use the sysctl_sched_migration_cost as the upper - * limit, plus a litle extra to avoid off by ones. */ - sd->max_newidle_lb_cost = - min(cost, sysctl_sched_migration_cost + 200); + sd->max_newidle_lb_cost = cost; sd->last_decay_max_lb_cost = jiffies; } else if (time_after(jiffies, sd->last_decay_max_lb_cost + HZ)) { /* @@ -12920,17 +12914,10 @@ static int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf) t1 = sched_clock_cpu(this_cpu); domain_cost = t1 - t0; + update_newidle_cost(sd, domain_cost); + curr_cost += domain_cost; t0 = t1; - - /* - * Failing newidle means it is not effective; - * bump the cost so we end up doing less of it. - */ - if (!pulled_task) - domain_cost = (3 * sd->max_newidle_lb_cost) / 2; - - update_newidle_cost(sd, domain_cost); } /* |