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Subject: RE: Latency traces I cannot interpret (sa1100, 2.6.15-rc7-rt1)
From: Daniel Walker <dwalker@mvista.com>
To: kus Kusche Klaus <kus@keba.com>
Cc: Ingo Molnar <mingo@elte.hu>, Lee Revell <rlrevell@joe-job.com>,
       linux-kernel <linux-kernel@vger.kernel.org>
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Date: Mon, 02 Jan 2006 06:14:55 -0800
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On Mon, 2006-01-02 at 08:57 +0100, kus Kusche Klaus wrote:
>          
>   <idle>-0     0D...    1us+: preempt_schedule_irq (svc_preempt)
>   <idle>-0     0....    5us!: default_idle (cpu_idle)
>   <idle>-0     0D..1 8700us+: asm_do_IRQ (c021da48 1a 0)

Your trace appears to be showing an actual latency of 300us . The trace
starts at 8700us . The default_idle line above is showing interrupts are
enable, and preemption is enabled . So the tracing code really should be
ignoring the default_idle line since there is no reason to be tracing. 

Daniel

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