From: Thomas Gleixner <tglx@linutronix.de>
To: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
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, 01 Dec 2020 14:34:49 +0100 [thread overview]
Message-ID: <87blfdhcp2.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20201201114026.GB72897@lothringen>
On Tue, Dec 01 2020 at 12:40, Frederic Weisbecker wrote:
> On Tue, Dec 01, 2020 at 12:33:26PM +0100, Thomas Gleixner wrote:
>> > /*
>> > * 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);
>> > }
>>
>> Why not making all of this explicit instead of these conditionals?
>
> Hmm, I'm not sure I get what you suggest?
Instead of playing games with preeempt count and offsets and checking
for ksoftirqd, can't you just have:
account_hardirqtime()
account_softirqtime()
and call them from the right spots. See the below for illustration (it's
obviously incomplete).
Thanks,
tglx
---
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -377,6 +377,7 @@ static inline void invoke_softirq(void)
return;
if (!force_irqthreads) {
+ account_softirq_enter_time(current);
#ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
/*
* We can safely execute softirq on the current stack if
@@ -391,6 +392,7 @@ static inline void invoke_softirq(void)
* to prevent from any overrun.
*/
do_softirq_own_stack();
+ account_softirq_exit_time(current);
#endif
} else {
wakeup_softirqd();
@@ -417,7 +419,7 @@ static inline void __irq_exit_rcu(void)
#else
lockdep_assert_irqs_disabled();
#endif
- account_irq_exit_time(current);
+ account_hardirq_exit_time(current);
preempt_count_sub(HARDIRQ_OFFSET);
if (!in_interrupt() && local_softirq_pending())
invoke_softirq();
next prev parent reply other threads:[~2020-12-01 13:35 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
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 [this message]
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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