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Message-ID: <5bdc1c8b0510101412n714c4798v1482254f6f8e0386@mail.gmail.com>
Date: Mon, 10 Oct 2005 14:12:18 -0700
From: Mark Knecht <markknecht@gmail.com>
To: Daniel Walker <dwalker@mvista.com>
Subject: Re: Latency data - 2.6.14-rc3-rt13
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
       Lee Revell <rlrevell@joe-job.com>
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On 10/10/05, Daniel Walker <dwalker@mvista.com> wrote:
> On Mon, 2005-10-10 at 13:16 -0700, Mark Knecht wrote:
> > Hi,
>
> >
> > How can I get data that would be more useful in terms of real debug?
>
> The IRQ off times look like the worst . If you do "make menuconfig"
>
> then goto Kernel Hacking and select
> "Interrupts-off critical section latency timing"
> Then select "Latency tracing"
>
> Then when you boot the system before run the following,
>
> "echo 0 > /proc/sys/kernel/preempt_max_latency"

So this disables the tracing of preempt times but keeps IRQ times on? Cool.
>
>
> That will record a trace for every maximum latency observed for IRQ
> latency . You can view the trace with this command
> "cat /proc/latency_trace" , and you can attach the trace to an email to
> LKML so we can review it (compress it if it's big though) .
>
> Daniel

Will do. Building now. I'll be back later.

Is there anything specific I should look for in the traces myself?
Anyway to help narrow it down?

Cheers,
Mark
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