Date: Sun, 18 Jul 2010 22:41:09 +0300 From: Kostik Belousov <kostikbel@gmail.com> To: Doug Barton <dougb@freebsd.org> Cc: freebsd-current@freebsd.org, Rui Paulo <rpaulo@freebsd.org> Subject: Re: Why is intr taking up so much cpu? Message-ID: <20100718194109.GU2381@deviant.kiev.zoral.com.ua> In-Reply-To: <4C43541C.3060101@FreeBSD.org> References: <alpine.BSF.2.00.1007170013191.7378@qbhto.arg> <A81B337F-5932-44B1-BDB4-D9DD36332A16@lavabit.com> <alpine.BSF.2.00.1007171103060.1546@qbhto.arg> <F653FF83-D9CF-42A2-AE9A-B8F914090065@FreeBSD.org> <alpine.BSF.2.00.1007171208010.1538@qbhto.arg> <20100717192128.GM2381@deviant.kiev.zoral.com.ua> <alpine.BSF.2.00.1007180113370.1707@qbhto.arg> <20100718103003.GO2381@deviant.kiev.zoral.com.ua> <4C43541C.3060101@FreeBSD.org>
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On Sun, Jul 18, 2010 at 12:21:00PM -0700, Doug Barton wrote:
> On 07/18/10 03:30, Kostik Belousov wrote:
> > On Sun, Jul 18, 2010 at 01:14:41AM -0700, Doug Barton wrote:
> >> On Sat, 17 Jul 2010, Kostik Belousov wrote:
> >>
> >>> Run top in the mode where all system threads are shown separately
> >>> (e.g. top -HS seems to do it), then watch what thread eats the proces=
sor.
> >>
> >> And the winner is!
> >>
> >> 11 root -32 - 0K 168K WAIT 0 0:28 18.02% {swi4:=
=20
> >> clock}
> >> 11 root 21 -64 - 0K 168K WAIT 0 1:17 18.90% intr
> >>
> >> The first is with -H, the second without.
> >
> > Most likely it is some callout handling. Just in case, do you have
> > console screensaver active ?
>=20
> I assume you mean "saver=3Dyes" in rc.conf, and the answer is no, I am not
> using that. Usually I run xscreensaver, but at the time this happened I
> was not. I do have DPMS enabled in my X config though.
>=20
> Any suggestions on how to dig deeper on this? Are there any settings I
> can twiddle to try and mitigate it?
When intr time starts accumulating again, try to do
"procstat -kk <intr process pid>" and correlate the clock thread tid
with the backtrace. Might be, it helps to guess what callouts are eating
the CPU.
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