Date: Tue, 18 Jul 2006 14:41:26 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-hackers@freebsd.org Cc: Deomid Ryabkov <myself@rojer.pp.ru>, Gareth McCaughan <gmccaughan@synaptics-uk.com> Subject: Re: "swiN: clock sio" process taking 75% CPU Message-ID: <200607181441.26875.jhb@freebsd.org> In-Reply-To: <200607181804.44813.gmccaughan@synaptics-uk.com> References: <200607181317.33416.gmccaughan@synaptics-uk.com> <44BD044A.4090509@rojer.pp.ru> <200607181804.44813.gmccaughan@synaptics-uk.com>
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On Tuesday 18 July 2006 13:04, Gareth McCaughan wrote: > On Tuesday 2006-07-18 16:54, Deomid Ryabkov wrote: > > Gareth McCaughan wrote: > > > > > About 6 minutes after booting (on three occasions, but I > > > don't guarantee this doesn't vary), a process (well, a > > > kernel interrupt thread, I guess) that appears in the > > > output of "ps" as "[swi4: clock sio]" begins to use > > > about 3/4 of the machine's CPU. > > > > I recall seeing similar behavior on a Sun V20z, running 5.x at the time. > > I have definitely seen a lot of interrupts and CPU usage on the sio interrupt > > corresponding to serial console. Needless to say there was no activity > > on the console itself. > > I think turning off serial console solved that for me. > > Do you mean commenting out the entries in /etc/ttys related to > serial TTYs, or something else? (I've tried the former, and it > didn't help.) > > In the spirit of grotesque voodoo chicken-waving, I also tried > taking the "sio" device out of my kernel entirely. The problem > remains unaltered. In that case, something is scheduling a lot of timeouts (via callout_reset() or timeout()) or you have timeout handlers that are taking a very long time to run. There aren't any easy ways to debug this. :-P You can try turning on the DIGANOSTIC check in kern_timeout.c to catch long-running timeouts, and you can try adding some KTR traces to softclock() to see which timeout functions are running and try to do some analysis on that. -- John Baldwin
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