perf top: losing events?

From: Mike Galbraith
Date: Thu Jan 21 2010 - 00:42:26 EST


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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