From: Prarit Bhargava <prarit@redhat.com>
To: John Stultz <johnstul@us.ibm.com>
Cc: paulmck@linux.vnet.ibm.com,
Linux Kernel <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: RCU NOHZ, tsc, and clock_gettime
Date: Tue, 13 Nov 2012 10:18:30 -0500 [thread overview]
Message-ID: <50A264C6.4010906@redhat.com> (raw)
In-Reply-To: <50A185D7.9080902@us.ibm.com>
On 11/12/2012 06:27 PM, John Stultz wrote:
> Hey Prarit,
> Just back from being on leave, and wanted to check in on this. Did you ever
> get to run with an increase sample size to see how that affected things? Its
> exactly your point that the non-NOHZ case could align the execution of a short
> run in a way that you always see good results, where as with NOHZ the alignment
> might not be the same, so you see periodic delays from timer interrupts, etc.
>
> Anyway, let me know if this got resolved or not.
Hey John,
I never did narrow this down, although this "disappears" with the move to the
lower resolution patches in upstream. I have not, however, done any testing to
see if the situation is actually resolved or if we just reduced the problem by a
factor of 1000 ;)
P.
next prev parent reply other threads:[~2012-11-13 15:18 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-11 18:52 RCU NOHZ, tsc, and clock_gettime Prarit Bhargava
2012-10-11 19:51 ` John Stultz
2012-10-11 20:21 ` Paul E. McKenney
2012-10-12 15:40 ` Prarit Bhargava
2012-10-15 14:56 ` Paul E. McKenney
2012-11-12 23:27 ` John Stultz
2012-11-13 15:18 ` Prarit Bhargava [this message]
2012-10-12 18:27 ` Prarit Bhargava
2012-10-14 22:51 ` Paul E. McKenney
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