linux-kernel - perf top: losing events?

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Date:	Thu, 21 Jan 2010 06:42:08 +0100
From:	Mike Galbraith <efault@....de>
To:	Arnaldo Carvalho de Melo <acme@...hat.com>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	LKML <linux-kernel@...r.kernel.org>
Subject: perf top: losing events?

Greetings Arnaldo,

------------------------------------------------------------------------------------------------------------------------------
   PerfTop:     670 irqs/sec  kernel:14.6% [1000Hz cycles],  (all, cpu: 3)
------------------------------------------------------------------------------------------------------------------------------

             samples  pcnt function            DSO
             _______ _____ ___________________ ________________________________________________________________

            12535.00 82.1% main                /root/bin/pert
              302.00  2.0% clear_page_c        [kernel.kallsyms]
              169.00  1.1% _int_malloc         /lib64/libc-2.9.so
              168.00  1.1% page_fault          [kernel.kallsyms]
              138.00  0.9% yylex               /usr/local/src/kernel/linux-2.6.33.git/scripts/genksyms/genksyms
              121.00  0.8% __GI_memset         /lib64/libc-2.9.so
              117.00  0.8% copy_page_c         [kernel.kallsyms]
               96.00  0.6% _raw_spin_lock      [kernel.kallsyms]
               79.00  0.5% use_config          /usr/local/src/kernel/linux-2.6.33.git/scripts/basic/fixdep

If only 100% userland hog (pert) is running, I see the expected 1KHz
irqs/sec.  As soon as I start a kbuild with it, irqs/sec drops, though
NMIs are indeed happening at 1KHz.

Bisection points to 5b2bb75 perf top: Support userspace symbols too.

	-Mike

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