From: Thomas Gleixner <tglx@linutronix.de>
To: Pedro R <eusou15@yahoo.com>
Cc: Nicholas Mc Guire <mcguire@lzu.edu.cn>, linux-rt-users@vger.kernel.org
Subject: Re: Strange spikes using linux-rt kernel
Date: Mon, 6 Jul 2009 17:30:38 +0200 (CEST) [thread overview]
Message-ID: <alpine.LFD.2.00.0907061726190.19480@localhost.localdomain> (raw)
In-Reply-To: <190013.60215.qm@web112503.mail.gq1.yahoo.com>
Pedro,
please do not top post and please fix your mailer to do proper
linewraps at around 78 chars.
On Fri, 3 Jul 2009, Pedro R wrote:
> The posixcputmr/0 and watchdog/0 seem to be running at a higher
> priority! Is this normal?
Yes, but they do not interfere and are not the cause of your latency
problems.
> I looked at the distribution of the jitter and these are very rare
> spikes. I ran cyclictest with 5 threads for 30000 cycles and the
> delay is always around 10-35 us except when there is a spike, which
> goes from 1000 to 7000us. These spikes are one-time ocurrences -
> they only last for one sample and sometimes only one of the threads
> is delayed, on other occasions 2 or 3 threads are delayed...
Can you please add "nohz=off" to the kernel command line and check
whether the problem persists ?
Thanks,
tglx
next prev parent reply other threads:[~2009-07-06 15:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-03 15:50 Strange spikes using linux-rt kernel Pedro R
2009-07-06 15:30 ` Thomas Gleixner [this message]
-- strict thread matches above, loose matches on Subject: below --
2009-07-03 14:04 Pedro R
2009-07-03 14:48 ` Nicholas Mc Guire
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