Hi Dietmar, I understand, thank you for your review and very detailed explanation.
Yours, Qi Zheng On 2020/8/3 下午3:36, Dietmar Eggemann wrote:
On 02/08/2020 06:51, Qi Zheng wrote:I think the unbalance scenario here should be that we need to do active balance but it is not actually done. So fix it. Signed-off-by: Qi Zheng <arch0.zh...@gmail.com> --- kernel/sched/fair.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 2ba8f230feb9..6d8c53718b67 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -9710,7 +9710,7 @@ static int load_balance(int this_cpu, struct rq *this_rq, } else sd->nr_balance_failed = 0;- if (likely(!active_balance) || voluntary_active_balance(&env)) {+ if (likely(!active_balance) && voluntary_active_balance(&env)) { /* We were unbalanced, so reset the balancing interval */ sd->balance_interval = sd->min_interval; } else {Active balance is potentially already been done when we reach this code. See 'if (need_active_balance(&env))' and 'if (!busiest->active_balance)' further up. Here we only reset sd->balance_interval in case: (A) the last load balance wasn't an active one (B) the reason for the active load balance was: (1) asym packing (2) capacity of src_cpu is reduced compared to the one of dst_cpu (3) misfit handling (B) is done to not unnecessarily increase of balance interval, see commit 46a745d90585 ("sched/fair: Fix unnecessary increase of balance interval").
