Red Hat ENTERPRISE LINUX 5.4 - SYSTEMTAP BEGINNERS GUIDE Informations techniques télécharger pdf (Page 116)

102 System Analysis and Tuning Guide

File Description

reset_pmds_count Number of times

pfm_reset_pmds() is called

set_switch_count Number of event set switches

set_switch_ns Number of nanoseconds spent in the

set switching rountine

Average cost of switching sets =

set_switch_ns /

set_switch_count

This might be useful to compare your metrics before and after the perfmon run. For

example, collect your data first:

for i in /sys/kernel/debug/perfmon/cpu0/*; do

echo "$i:"; cat $i

done >> pfmon-before.txt

Run your performance monitoring, maybe restrict it to a specific CPU:

pfmon --cpu-list=0 ...

Collect your data again:

for i in /sys/kernel/debug//perfmon/cpu0/*; do

echo "$i:"; cat $i

done >> pfmon-after.txt

Compare these two files:

diff -u pfmon-before.txt pfmon-after.txt

7.5 For More Information

This chapter only provides a short overview. Refer to the following links for more in-

formation:

http://perfmon2.sourceforge.net/

The project home page.

http://www.iop.org/EJ/arti

cle/1742-6596/119/4/042017/jpconf8_119_042017.pdf

A good overview as PDF.

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Red Hat ENTERPRISE LINUX 5.4 - SYSTEMTAP BEGINNERS GUIDE Informations techniques Page 116