From: Thomas Gleixner <tglx@linutronix.de>
To: "Sarin, Suseelan" <suseelan@gmail.com>
Cc: linux-rt-users@vger.kernel.org
Subject: Re: Calculating latency using high resolution timer
Date: Wed, 9 Jun 2010 20:30:38 +0200 (CEST) [thread overview]
Message-ID: <alpine.LFD.2.00.1006092028280.2933@localhost.localdomain> (raw)
In-Reply-To: <AANLkTinCc-TibWfphYTZtXhDh2flvrcXNW_bO3SUetyV@mail.gmail.com>
On Wed, 9 Jun 2010, Sarin, Suseelan wrote:
> Hi All,
>
> My real-time program has a thread which needs to run at every 2ms. I
> want to calculate the latency of this thread and I am using
> clock_gettime for this. I am bit confused here that whether I can do
> this. My doubt is, if the system is loaded to the extend that an RT
> task can have considerable latency, can I trust the time read from the
> high resolution timer of the system?
Yes, it's accurate. cyclictest relies on that as well.
> Also, with these measurements, I am seeing a ~5msec latency. Is there
> a way I can exactly point out the reason for this latency?
Tracing. See cyclictest.c for how that's done.
Thanks,
tglx
next prev parent reply other threads:[~2010-06-09 18:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <AANLkTikuWI08hHb2BdzicdEYKO4SdQlCL17gDQgqwrKz@mail.gmail.com>
2010-06-09 16:21 ` Calculating latency using high resolution timer Sarin, Suseelan
2010-06-09 18:30 ` Thomas Gleixner [this message]
2010-06-10 6:13 ` Sarin, Suseelan
[not found] ` <4C0FD3E4.9090304@gmail.com>
2010-06-10 6:11 ` Sarin, Suseelan
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