Re: Latency data - 2.6.14-rc3-rt13

[Sven-Thorsten Dietrich <sven@mvista.com>]

On Mon, 2005-10-10 at 20:45 -0700, Mark Knecht wrote:
> On 10/10/05, Mark Knecht <markknecht@gmail.com> wrote:
> >
> > ( softirq-timer/0-3    |#0): new 3997 us maximum-latency critical section.
> 
> So the root cause of this 4mS delay is the 250Hz timer. If I change
> the system to use the 1Khz timer then the time in this section drops,
> as expected, to 1mS.
> 
> ( softirq-timer/0-3    |#0): new 998 us maximum-latency critical section.
>  => started at timestamp 121040020: <acpi_processor_idle+0x20/0x379>
>  =>   ended at timestamp 121041019: <thread_return+0xb5/0x11a>
> 
> So, thinking very interesting here I think.
> 

Maximum preemption latencies near the timer period 
are sometimes indicative of mismatched 
preempt_disable/preempt_enable pairs in the code.

Usually the scheduler warns about that on the console, however.

Sven

> Back to the drawing board as to my xruns.
> 
> - Mark
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