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From: Thomas Gleixner <tglx@linutronix.de>
To: Oliver Nittka <oly@nittka.com>
Cc: RT <linux-rt-users@vger.kernel.org>
Subject: Re: Beginner's questions on userspace latency
Date: Fri, 22 Mar 2013 21:23:06 +0100 (CET)	[thread overview]
Message-ID: <alpine.LFD.2.02.1303222121100.22263@ionos> (raw)
In-Reply-To: <514CB285.4050100@nittka.com>

On Fri, 22 Mar 2013, Oliver Nittka wrote:
> The timing is fine most of the time, but putting the system under heavy
> CPU and USB load leads to occasional glitches where the time between two
> ioctl calls can be as high as 50ms.

The kernel tracer is your friend. Enable the kernel function tracer
and add a check into your application which detects the issue and then
stops the trace. See the cyclictest source code for an example how to
do that.

Thanks,

	tglx

  parent reply	other threads:[~2013-03-22 20:23 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-22 19:35 Beginner's questions on userspace latency Oliver Nittka
2013-03-22 20:06 ` Staffan Tjernstrom
2013-03-22 20:21 ` Tim Sander
2013-03-22 20:23 ` Thomas Gleixner [this message]
2013-03-24 20:09 ` Oliver Nittka

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