Messages in this thread | | | Date | Tue, 1 Dec 2020 12:23:38 +0100 | From | Frederic Weisbecker <> | Subject | Re: [PATCH 4/5] irqtime: Move irqtime entry accounting after irq offset incrementation |
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On Tue, Dec 01, 2020 at 10:20:11AM +0100, Peter Zijlstra wrote: > On Tue, Dec 01, 2020 at 01:12:25AM +0100, Frederic Weisbecker wrote: > > +static s64 irqtime_get_delta(struct irqtime *irqtime) > > { > > + int cpu = smp_processor_id(); > > s64 delta; > > > > delta = sched_clock_cpu(cpu) - irqtime->irq_start_time; > > irqtime->irq_start_time += delta; > > > > + return delta; > > +} > > + > > +/* Called after incrementing preempt_count on {soft,}irq_enter */ > > +void irqtime_account_enter(struct task_struct *curr) > > +{ > > + struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime); > > + u64 delta; > > + > > + if (!sched_clock_irqtime) > > + return; > > + > > + delta = irqtime_get_delta(irqtime); > > + /* > > + * We do not account for softirq time from ksoftirqd here. > > + * We want to continue accounting softirq time to ksoftirqd thread > > + * in that case, so as not to confuse scheduler with a special task > > + * that do not consume any time, but still wants to run. > > + */ > > + if ((irq_count() == (SOFTIRQ_OFFSET | HARDIRQ_OFFSET)) && > > + curr != this_cpu_ksoftirqd()) > > + irqtime_account_delta(irqtime, delta, CPUTIME_SOFTIRQ); > > +} > > + > > +/* Called before decrementing preempt_count on {soft,}irq_exit */ > > +void irqtime_account_exit(struct task_struct *curr) > > +{ > > + struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime); > > + u64 delta; > > + > > + if (!sched_clock_irqtime) > > + return; > > + > > + delta = irqtime_get_delta(irqtime); > > /* > > * We do not account for softirq time from ksoftirqd here. > > * We want to continue accounting softirq time to ksoftirqd thread > > > Urgh... > > > Why not something like: > > void irqtime_account_irq(struct task_struct *curr, unsigned int offset) > { > struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime); > unsigned int pc = preempt_count() - offset; > s64 delta; > int cpu; > > if (!sched_clock_irqtime) > return; > > cpu = smp_processor_id(); > delta = sched_clock_cpu(cpu) - irqtime->irq_start_time; > irqtime->irq_start_time += delta; > > /* > * We do not account for softirq time from ksoftirqd here. > * We want to continue accounting softirq time to ksoftirqd thread > * in that case, so as not to confuse scheduler with a special task > * that do not consume any time, but still wants to run. > */ > if (pc & HARDIRQ_MASK) > irqtime_account_delta(irqtime, delta, CPUTIME_IRQ); > else if ((pc & SOFTIRQ_OFFSET) && curr != this_cpu_ksoftirqd()) > irqtime_account_delta(irqtime, delta, CPUTIME_SOFTIRQ); > } > >
Right that's better, I'll do that.
Thanks.
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