From: Peter Zijlstra <peterz@infradead.org>
To: Venkatesh Pallipadi <venki@google.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>,
Ingo Molnar <mingo@elte.hu>, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Balbir Singh <balbir@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org, Paul Turner <pjt@google.com>
Subject: Re: [PATCH] si time accounting accounts bh_disable'd time to si
Date: Thu, 30 Sep 2010 13:17:01 +0200 [thread overview]
Message-ID: <1285845421.2144.12.camel@laptop> (raw)
In-Reply-To: <1285619753-10892-1-git-send-email-venki@google.com>
On Mon, 2010-09-27 at 13:35 -0700, Venkatesh Pallipadi wrote:
> >> >> > You still do have the problem with local_bh_disable() though, since you
> >> >> > cannot distinguish between having bh disabled and processing softirq.
> >> >> >
> >> >> > So a hardirq that hits while you have bh disabled will inflate your
> >> >> > softirq time.
>
> >> >> Hmm, that bug is valid for CONFIG_VIRT_CPU_ACCOUNTING=y as well.
> >> >
> >> > And nobody ever noticed?
> >> >
> >> Yes. I inherited the API from VIRT_CPU_ACCOUNTING along with this
> >> local_bh_disable bug. Agree that we need one extra bit to handle this
> >> case. I will take a stab at fixing this along with refresh of this
> >> patchset if no one else has beaten me to it until then.
> >
> >Make sure to only fix the softirq processing on the hardirq tail, not
> > the ksoftirqd one :-)
>
> softirq processing from hardirq tail and ksoftirqd are currently
> handled in the same way and I didn't see any issues changing both of
> them. Am I missing something?
Well, ksoftirq is a task and its runtime should be accounted to that
task, not softirq.. otherwise softirq and task time get all funny, makes
sense?
next prev parent reply other threads:[~2010-09-30 11:17 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-17 1:56 [PATCH 0/6] Proper kernel irq time accounting Venkatesh Pallipadi
2010-09-17 1:56 ` [PATCH 1/6] Consolidate account_system_vtime extern declaration Venkatesh Pallipadi
2010-09-17 1:56 ` [PATCH 2/6] Add IRQ_TIME_ACCOUNTING, finer accounting of CPU irq time Venkatesh Pallipadi
2010-09-19 11:11 ` Peter Zijlstra
2010-09-20 17:13 ` Venkatesh Pallipadi
2010-09-20 17:23 ` Peter Zijlstra
2010-09-19 11:21 ` Peter Zijlstra
2010-09-19 11:42 ` Peter Zijlstra
2010-09-19 12:01 ` Peter Zijlstra
2010-09-20 7:27 ` Martin Schwidefsky
2010-09-20 9:27 ` Peter Zijlstra
2010-09-20 17:16 ` Venkatesh Pallipadi
2010-09-20 17:26 ` Peter Zijlstra
2010-09-27 20:35 ` [PATCH] si time accounting accounts bh_disable'd time to si Venkatesh Pallipadi
2010-09-27 20:53 ` Eric Dumazet
2010-09-27 21:11 ` Venkatesh Pallipadi
2010-09-27 21:16 ` Eric Dumazet
2010-09-30 11:17 ` Peter Zijlstra [this message]
2010-09-17 1:56 ` [PATCH 3/6] x86: Add IRQ_TIME_ACCOUNTING in x86 Venkatesh Pallipadi
2010-09-17 1:56 ` [PATCH 4/6] sched: Do not account irq time to current task Venkatesh Pallipadi
2010-09-19 11:28 ` Peter Zijlstra
2010-09-20 17:33 ` Venkatesh Pallipadi
2010-09-20 17:38 ` Peter Zijlstra
2010-09-20 17:40 ` Venkatesh Pallipadi
2010-09-17 1:56 ` [PATCH 5/6] sched: Remove irq time from available CPU power Venkatesh Pallipadi
2010-09-19 11:31 ` Peter Zijlstra
2010-09-20 17:38 ` Venkatesh Pallipadi
2010-09-17 1:56 ` [PATCH 6/6] Export per cpu hardirq and softirq time in proc Venkatesh Pallipadi
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