From mboxrd@z Thu Jan  1 00:00:00 1970
To: 9fans@cse.psu.edu
Subject: Re: [9fans] syscall spikes
From: "Russ Cox" <rsc@swtch.com>
Date: Wed, 18 Apr 2007 12:53:12 -0400
In-Reply-To: <9ab217670704170715i1e62ed48k9817177886add100@mail.gmail.com>
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> I've been having syscall spikes. It's really weird. There will be
>>40,000 in 1 second, (according to stats(8)) and it appears at a
> fairly regular interval. I've tried running kprof, but I'm not sure
> that it's running a global profile. Namely, when I come out of it, I
> have tons of time spent in ``halt'', with very, very few (<100)
> syscalls. Any ideas what I can do to find the culprit? It's gapping
> sound playback, which is really annoying.

You figured out that this is caused by two timesyncs.

However, it might not be caused by the timesyncs actually
issuing that many system calls as much as fighting over
what time means.  So probably you're not having 40,000
system calls but in fact the clock is being slowed/stopped
in the kernel, which makes the devaudio sleep take too long.

Russ