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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: Wed, 2 Dec 2020 13:36:48 +0100	[thread overview]
Message-ID: <20201202123648.GI3021@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20201202115732.27827-5-frederic@kernel.org>

On Wed, Dec 02, 2020 at 12:57:31PM +0100, Frederic Weisbecker wrote:
> IRQ time entry is currently accounted before HARDIRQ_OFFSET or
> SOFTIRQ_OFFSET are incremented. This is convenient to decide to which
> index the cputime to account is dispatched.
> 
> Unfortunately it prevents tick_irq_enter() from being called under
> HARDIRQ_OFFSET because tick_irq_enter() has to be called before the IRQ
> entry accounting due to the necessary clock catch up. As a result we
> don't benefit from appropriate lockdep coverage on tick_irq_enter().
> 
> To prepare for fixing this, move the IRQ entry cputime accounting after
> the preempt offset is incremented. This requires the cputime dispatch
> code to handle the extra offset.
> 
> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

  reply	other threads:[~2020-12-02 12:37 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
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 1/5] sched/cputime: Remove symbol exports from IRQ time accounting Frederic Weisbecker
2020-12-02 19:23   ` [tip: irq/core] " tip-bot2 for Frederic Weisbecker
2020-12-02 19:28   ` [PATCH 1/5] " Christian Borntraeger
2020-12-02 11:57 ` [PATCH 2/5] s390/vtime: Use the generic IRQ entry accounting Frederic Weisbecker
2020-12-02 19:23   ` [tip: irq/core] " tip-bot2 for Frederic Weisbecker
2020-12-02 19:34   ` [PATCH 2/5] " Christian Borntraeger
2020-12-02 11:57 ` [PATCH 3/5] sched/vtime: Consolidate IRQ time accounting Frederic Weisbecker
2020-12-02 19:23   ` [tip: irq/core] " tip-bot2 for 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 [this message]
2020-12-02 19:23   ` [tip: irq/core] " tip-bot2 for Frederic Weisbecker
2020-12-28  2:15   ` [PATCH 4/5] " 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
2020-12-02 11:57 ` [PATCH 5/5] irq: Call tick_irq_enter() inside HARDIRQ_OFFSET Frederic Weisbecker
2020-12-02 19:23   ` [tip: irq/core] " tip-bot2 for Frederic Weisbecker
  -- strict thread matches above, loose matches on Subject: below --
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 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
2020-12-01 14:35           ` Frederic Weisbecker
2020-12-01 15:01             ` Peter Zijlstra
2020-12-01 15:53               ` Thomas Gleixner

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