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Date: Mon, 19 Jul 2010 18:03:21 -0700 (PDT)
From: Doug Barton <dougb@FreeBSD.org>
To: Dan Nelson <dnelson@allantgroup.com>
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Cc: Kostik Belousov <kostikbel@gmail.com>, freebsd-current@freebsd.org,
	Rui Paulo <rpaulo@freebsd.org>
Subject: Re: Why is intr taking up so much cpu?
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I added options KDTRACE_HOOKS to my kernel config, built a new kernel, 
and rebooted. I decided to try your script before things went sideways 
so I'd have an idea of what to expect, and it didn't work:

dtrace: failed to initialize dtrace: DTrace device not available on 
system

Is there something else I need to do to enable it?


Doug


On Sun, 18 Jul 2010, Dan Nelson wrote:

> You can also use dtrace to get a count of callouts and their time spent.
> Run this for a few seconds then hit ^C:
>
> #! /usr/sbin/dtrace -s
> /* #pragma D option quiet */
>
> callout_execute:::callout_start
> {
>        this->start = timestamp;
> }
>
> callout_execute:::callout_end
> {
>        this->end = timestamp;
> /*      printf("%a %d\n",args[0]->c_func, this->end - this->start); */
>        @times[args[0]->c_func] = quantize(this->end - this->start);
> /*      @times[args[0]->c_func] = lquantize(this->end - this->start,0,300000,10000); */
>        @counts[args[0]->c_func] = count();
> }
>
> END
> {
>        printa("%a %@u\n",@times);
>        printa("%a %@u\n",@counts);
> }