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Date:      Tue, 20 Jul 2010 16:26:43 +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:  <20100720132643.GH2381@deviant.kiev.zoral.com.ua>
In-Reply-To: <alpine.BSF.2.00.1007192302300.1725@qbhto.arg>
References:  <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> <20100718194109.GU2381@deviant.kiev.zoral.com.ua> <alpine.BSF.2.00.1007192302300.1725@qbhto.arg>

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On Mon, Jul 19, 2010 at 11:05:26PM -0700, Doug Barton wrote:
> On Sun, 18 Jul 2010, Kostik Belousov wrote:
>=20
> >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.
>=20
> Ok, I thought I was going to be able to do this easily but I didn't=20
> realize that the numbers in the second column were thread ids, and I=20
> don't know how to "correlate the clock thread tid with the backtrace."=20
> Can you give me a hint? :)

It already printed the thread names, so no need. Unfortunately,
the clock threads were running instead of blocking etc (I suspected
that this would be a case), so procstat cannot get the backtrace.
Another option is to do a backtrace from ddb.

I cannot get much information from the dtrace snippets you posted in
parallel. I can only see that some threads used msleep (?) with timeout
a lot, and something at the address 0xc67bbe90 also raised a head.
Can you manually lookup nearby symbol for 0xc67bbe90 ?

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