Re: Latency data - 2.6.14-rc3-rt13

From: Daniel Walker
Date: Mon Oct 10 2005 - 15:49:44 EST

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"

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) .


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