Messages in this thread | | | Date | Thu, 28 Sep 2023 23:26:58 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] psi: update psi irqtime when the irq delta is nozero |
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* Lu Jialin <lujialin4@huawei.com> wrote:
> If update psi irqtime whether the irq delta is zero or not, the performance > will be degradation when update_rq_clock_task works frequently. > Therefore, just update psi irqtime whether the irq delta is nozero. > performace test of times(libmicro): > 1) without psi_account_irqtime in update_rq_clock_task > [root@arm64_perf]# ./times -E -C 200 -L -S -W -N "times" -I 200 > Running: times# ./../bin-arm64/times -E -C 200 -L -S -W -N times -I 200 > prc thr usecs/call samples errors cnt/samp > times 1 1 0.45210 188 0 500 > > 2) psi_account_irqtime in update_rq_clock_task > [root@arm64_perf]# ./times -E -C 200 -L -S -W -N "times" -I 200 > Running: times# ./../bin-arm64/times -E -C 200 -L -S -W -N times -I 200 > prc thr usecs/call samples errors cnt/samp > times 1 1 0.49408 196 0 500 > > 3) psi_account_irqtime in update_rq_clock_task when irq delta is nozero > [root@arm64_perf]# ./times -E -C 200 -L -S -W -N "times" -I 200 > Running: times# ./../bin-arm64/times -E -C 200 -L -S -W -N times -I 200 > prc thr usecs/call samples errors cnt/samp > times 1 1 0.45158 195 0 500 > > Signed-off-by: Lu Jialin <lujialin4@huawei.com> > --- > kernel/sched/core.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index c52c2eba7c73..69c4f229d6d1 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -722,7 +722,8 @@ static void update_rq_clock_task(struct rq *rq, s64 delta) > > rq->prev_irq_time += irq_delta; > delta -= irq_delta; > - psi_account_irqtime(rq->curr, irq_delta); > + if (irq_delta) > + psi_account_irqtime(rq->curr, irq_delta); > delayacct_irq(rq->curr, irq_delta);
Erm, if irq_delta is zero, then a whole bunch of code around the place you modified becomes NOP as well, right?
Thanks,
Ingo
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