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Date: Tue, 19 Mar 2013 16:57:37 +0200
From: Andriy Gapon <avg@FreeBSD.org>
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To: Freddie Cash <fjwcash@gmail.com>
Subject: Re: Strange slowdown when cache devices enabled in ZFS
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on 15/03/2013 16:58 Freddie Cash said the following:
> How does one do that?  I've never done that before.
> 
> Point me to some docs, and I'll see what I can find out.

hwpmc(4), pmcstat(8)
and/or
/usr/share/dtrace/toolkit/hotkernel
and/or (just an example)
dtrace -n 'profile:::profile-4001 { @stacks[pid, tid, execname, stack()] =
count(); } END { trunc(@stacks, 10); printa(@stacks); }'



> On Fri, Mar 15, 2013 at 4:34 AM, Andriy Gapon <avg@freebsd.org
> <mailto:avg@freebsd.org>> wrote:
> 
>     on 14/03/2013 20:13 Freddie Cash said the following:
>     > the l2arc_feed_thread of zfskern will spin until it takes up 100%
>     > of a CPU core
> 
>     If you see a thread taking 100% where it shouldn't, then just profile it and
>     actually see what it's doing.

-- 
Andriy Gapon