From: Peter Zijlstra <peterz@infradead.org>
To: Jan Engelhardt <jengelh@medozas.de>
Cc: Arjan van de Ven <arjan@infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: System tick rate
Date: Fri, 13 Mar 2009 09:49:27 +0100 [thread overview]
Message-ID: <1236934167.5188.195.camel@laptop> (raw)
In-Reply-To: <alpine.LSU.2.00.0903121541410.8068@fbirervta.pbzchgretzou.qr>
On Thu, 2009-03-12 at 15:45 +0100, Jan Engelhardt wrote:
> On Thursday 2009-03-12 15:21, Arjan van de Ven wrote:
> >On Thu, 12 Mar 2009 14:38:19 +0100 (CET) Jan Engelhardt wrote:
> >>
> >> is there an "official" way of obtaining the current tick rate when
> >> CONFIG_NO_HZ?
> >
> >what does "current tick rate" mean for you in a no-hz situation ?
> >is it the HZ value (which is supposed to be invisible from userspace,
> >so good luck) or the wakeup count ?
>
> Hm, I guess what I want is the number of timer interrupts which
> occurred within the observation period that called the scheduler
> code. (So that excludes RTC on usual x86en.)
There is no tick rate with NO_HZ mode, only a max tick rate, but as
Arjan said, not even that is exposed to user-space.
I think Dave's Niagra has the crown here, because he ran into some bug
in the NO_HZ code some while back because he idled longer than we ever
seen before. I think it was in the order of 30 minutes or something
without a single wakeup of the CPU.
next prev parent reply other threads:[~2009-03-13 8:49 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-12 13:38 System tick rate Jan Engelhardt
2009-03-12 14:21 ` Arjan van de Ven
2009-03-12 14:45 ` Jan Engelhardt
2009-03-13 8:49 ` Peter Zijlstra [this message]
2009-03-16 18:11 ` Jan Engelhardt
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