From: Peter Zijlstra <peterz@infradead.org>
To: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
Tony Luck <tony.luck@intel.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Heiko Carstens <hca@linux.ibm.com>
Subject: Re: [PATCH 4/5] irqtime: Move irqtime entry accounting after irq offset incrementation
Date: Tue, 1 Dec 2020 10:20:11 +0100 [thread overview]
Message-ID: <20201201092011.GS2414@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20201201001226.65107-5-frederic@kernel.org>
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);
}
next prev parent reply other threads:[~2020-12-01 9:21 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-01 0:12 [PATCH 0/5] irq: Reorder time handling against HARDIRQ_OFFSET on IRQ entry v2 Frederic Weisbecker
2020-12-01 0:12 ` [PATCH 1/5] sched/cputime: Remove symbol exports from IRQ time accounting Frederic Weisbecker
2020-12-01 0:12 ` [PATCH 2/5] sched/vtime: Consolidate " Frederic Weisbecker
2020-12-01 0:12 ` [PATCH 3/5] s390/vtime: Convert to consolidated " Frederic Weisbecker
2020-12-01 0:12 ` [PATCH 4/5] irqtime: Move irqtime entry accounting after irq offset incrementation Frederic Weisbecker
2020-12-01 9:20 ` Peter Zijlstra [this message]
2020-12-01 11:23 ` Frederic Weisbecker
2020-12-01 11:33 ` Thomas Gleixner
2020-12-01 11:40 ` Frederic Weisbecker
2020-12-01 13:34 ` Thomas Gleixner
2020-12-01 14:35 ` Frederic Weisbecker
2020-12-01 15:01 ` Peter Zijlstra
2020-12-01 15:53 ` Thomas Gleixner
2020-12-01 0:12 ` [PATCH 5/5] irq: Call tick_irq_enter() inside HARDIRQ_OFFSET Frederic Weisbecker
2020-12-02 11:57 [PATCH 0/5] irq: Reorder time handling against HARDIRQ_OFFSET on IRQ entry v3 Frederic Weisbecker
2020-12-02 11:57 ` [PATCH 4/5] irqtime: Move irqtime entry accounting after irq offset incrementation Frederic Weisbecker
2020-12-02 12:36 ` Peter Zijlstra
2020-12-28 2:15 ` Qais Yousef
2020-12-29 13:41 ` Frederic Weisbecker
2020-12-29 14:12 ` Qais Yousef
2020-12-29 14:30 ` Frederic Weisbecker
2020-12-29 15:58 ` Qais Yousef
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