Re: Latency data - 2.6.14-rc3-rt13
From: Mark Knecht
Date: Mon Oct 10 2005 - 16:12:40 EST
On 10/10/05, Daniel Walker <dwalker@xxxxxxxxxx> 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) .
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?
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