diff options
| author | Vincent Guittot | 2021-01-07 11:33:24 +0100 |
|---|---|---|
| committer | Peter Zijlstra | 2021-01-14 11:20:11 +0100 |
| commit | 8a41dfcda7a32ed4435c00d98a9dc7156b08b671 (patch) | |
| tree | 5458b36c971aadd7c3a29e4a30678d88c5c5db97 /kernel/sched | |
| parent | fc488ffd4297f661b3e9d7450dcdb9089a53df7c (diff) | |
sched/fair: Don't set LBF_ALL_PINNED unnecessarily
Setting LBF_ALL_PINNED during active load balance is only valid when there
is only 1 running task on the rq otherwise this ends up increasing the
balance interval whereas other tasks could migrate after the next interval
once they become cache-cold as an example.
LBF_ALL_PINNED flag is now always set it by default. It is then cleared
when we find one task that can be pulled when calling detach_tasks() or
during active migration.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lkml.kernel.org/r/20210107103325.30851-3-vincent.guittot@linaro.org
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/fair.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 13de7aede74f..48f99c8a52f9 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -9639,6 +9639,8 @@ redo: env.src_rq = busiest; ld_moved = 0; + /* Clear this flag as soon as we find a pullable task */ + env.flags |= LBF_ALL_PINNED; if (busiest->nr_running > 1) { /* * Attempt to move tasks. If find_busiest_group has found @@ -9646,7 +9648,6 @@ redo: * still unbalanced. ld_moved simply stays zero, so it is * correctly treated as an imbalance. */ - env.flags |= LBF_ALL_PINNED; env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running); more_balance: @@ -9772,10 +9773,12 @@ more_balance: if (!cpumask_test_cpu(this_cpu, busiest->curr->cpus_ptr)) { raw_spin_unlock_irqrestore(&busiest->lock, flags); - env.flags |= LBF_ALL_PINNED; goto out_one_pinned; } + /* Record that we found at least one task that could run on this_cpu */ + env.flags &= ~LBF_ALL_PINNED; + /* * ->active_balance synchronizes accesses to * ->active_balance_work. Once set, it's cleared |