Messages in this thread | | | Date | Tue, 1 Dec 2020 10:20:11 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 4/5] irqtime: Move irqtime entry accounting after irq offset incrementation |
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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); }
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