It seems to be rather a scheduler issue than a governor issue b/c the issue went away after unsetting CONFIG_FAIR_GROUP_SCHED.
If I unselect CONFIG_FAIR_GROUP_SCHED then the %CPU value raises 80% - which forces the ondemand governor do speed up the CPU frequency: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 7137 tfoerste 20 0 1796 488 428 R 95.5 0.0 0:01.40 factor 7083 dnetc 39 19 664 348 264 R 2.1 0.0 3:08.33 dnetc 4033 root 20 0 97252 9420 4008 R 0.7 0.9 0:09.43 X Am Samstag, 26. Januar 2008 schrieben Sie: > Toralf Förster wrote: > > > I use a 1-liner for a simple performance check : "time factor > > 819734028463158891" > > Here is the result for the new (Gentoo) kernel 2.6.24: > > > > With the ondemand governor of the I get: > > > > [EMAIL PROTECTED] ~/tmp $ time factor 819734028463158891 > > 819734028463158891: 3 273244676154386297 > > > > real 0m32.997s > > user 0m15.732s > > sys 0m0.014s > > > > With the ondemand governor the CPU runs at 600 MHz, > > whereas with the performance governor I get : > > > > [EMAIL PROTECTED] ~/tmp $ time factor 819734028463158891 > > 819734028463158891: 3 273244676154386297 > > > > real 0m10.893s > > user 0m5.444s > > sys 0m0.000s > > > > (~5.5 sec as I expected) b/c the CPU is set to 1.7 GHz. > > > > The ondeman governor of previous kernel versions however automatically > > increased > > the CPU speed from 600 MHz to 1.7 GHz. > > > > My system is a ThinkPad T41, I'll attach the .config > > During the test, run top, and watch your CPU usage. Does it go above 80% > (the default for > /sys/devices/system/cpu/cpu0/cpufreq/ondemand/up_threshold). > > ondemand CPUfreq governor has a few tunables, described in > Documentation/cpu-freq. One of them is up_threshold: > > up_threshold: defines what the average CPU usaged between the samplings > of 'sampling_rate' needs to be for the kernel to make a decision on > whether it should increase the frequency. For example when it is set > to its default value of '80' it means that between the checking > intervals the CPU needs to be on average more than 80% in use to then > decide that the CPU frequency needs to be increased. > > What CPUFreq processor driver are you using? > > > I had a similar problem with CPUfreq and dm-crypt (slow reads), see > (more setup problem than something kernel-related): > > http://blog.wpkg.org/2008/01/22/cpufreq-and-dm-crypt-performance-problems/ > > -- MfG/Sincerely Toralf Förster pgp finger print: 7B1A 07F4 EC82 0F90 D4C2 8936 872A E508 7DB6 9DA3
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