How to mearsure the average cpu frequency in linux?

Hi ,

I'm trying to measure the average cpu frequency in an DVFS enabled cpu for specific interval , the obvious way of periodically sampling /proc/cpuinfo has very large variants. The cpufreq-stats driver gave me some hope ,e.g.

cat /sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state 
2600000 118148
2000000 8562
1600000 11041
1200000 3428602    # lots of ticks is idle ticks

but unfortunately it is mixed with idle ticks(see patch "Do not account for idle time when tracking time_in_state"). During idle time it is probable that cpu will fall back to the lowest frequency ,thus skew the frequency distribution significantly .

The patch above utilize the account_idle_tick function to remove the idle ticks from statics, but it seems only works for xen kernel. Is there alternative way to measure average cpu frequency?

From serverfault Zhen

• Hi Zhen,

  perhaps sar is what you are looking for. As of release 9.0.0 of sysstat, sar can collect the cpu frequency. From man sar:

  -m     Report  power management statistics.  Note that these statistics
         depend on sadc option "-S POWER" to be collected.  The following
         value is displayed:
  
         MHz
           CPU clock frequency in MHz.
  

  Zhen : Hi Christian , I've checked the sysstat(9.0+) source code, it turns out that sysstat simply periodically check /proc/cpuinfo for the "MHz" line. So its reading is not very useful to me . Thanks anyway
  From Christian