On Sun, Jan 27, 2008 at 04:06:17PM +0100, Toralf Förster wrote: > > The third line (giving overall cpu usage stats) is what is interesting here. > > If you have more than one cpu, you can get cpu usage stats for each cpu > > in top by pressing 1. Can you provide this information with and w/o > > CONFIG_FAIR_GROUP_SCHED? > > This is what I get if I set CONFIG_FAIR_GROUP_SCHED to "y" > > top - 16:00:59 up 2 min, 1 user, load average: 2.56, 1.60, 0.65 > Tasks: 84 total, 3 running, 81 sleeping, 0 stopped, 0 zombie > Cpu(s): 49.7%us, 0.3%sy, 49.7%ni, 0.0%id, 0.0%wa, 0.3%hi, 0.0%si, 0.0%st > Mem: 1036180k total, 322876k used, 713304k free, 13164k buffers > Swap: 997880k total, 0k used, 997880k free, 149208k cached > > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND > 6070 dnetc 39 19 664 348 264 R 49.7 0.0 1:09.71 dnetc > 6676 tfoerste 20 0 1796 488 428 R 49.3 0.0 0:02.72 factor > > Stopping dnetc gives: > > top - 16:02:36 up 4 min, 1 user, load average: 2.50, 1.87, 0.83 > Tasks: 89 total, 3 running, 86 sleeping, 0 stopped, 0 zombie > Cpu(s): 99.3%us, 0.7%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st > Mem: 1036180k total, 378760k used, 657420k free, 14736k buffers > Swap: 997880k total, 0k used, 997880k free, 180868k cached > > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND > 6766 tfoerste 20 0 1796 488 428 R 84.9 0.0 0:05.41 factor
Thanks for this respone. This confirms that cpu's idle time is close to zero, as I intended to verify. > > If I am not mistaken, cpu ondemand gov goes by the cpu idle time stats, > > which should not be affected by FAIR_GROUP_SCHED. I will lookaround for > > other possible causes. On further examination, ondemand governor seems to have a tunable to ignore nice load. In your case, I see that dnetc is running at a positive nice value (19) which could explain why ondemand gov thinks that the cpu is only ~50% loaded. Can you check what is the setting of this knob in your case? # cat /sys/devices/system/cpu/cpu0/cpufreq/ondemand/ignore_nice_load You can set that to 0 to ask ondemand gov to include nice load into account while calculating cpu freq changes: # echo 0 > /sys/devices/system/cpu/cpu0/cpufreq/ondemand/ignore_nice_load This should restore the behavior of ondemand governor as seen in 2.6.23 in your case (even with CONFIG_FAIR_GROUP_SCHED enabled). Can you pls confirm if that happens? > As I stated our in http://lkml.org/lkml/2008/1/26/207 the issue is solved > after unselecting FAIR_GROUP_SCHED. I understand, but we want to keep CONFIG_FAIR_GROUP_SCHED enabled by default. Ingo, Most folks seem to be used to a global nice-domain, where a nice 19 task gives up cpu in competetion to a nice-0 task (irrespective of which userid's they belong to). CONFIG_FAIR_USER_SCHED brings noticeable changes wrt that. We could possibly let it be as it is (since that is what a server admin may possibly want when managing university servers) or modify it to be aware of nice-level (priority of user-sched entity is equivalent to highest prio task it has). In any case, I will send across a patch to turn off CONFIG_FAIR_USER_SCHED by default (and instead turn on CONFIG_FAIR_CGROUP_SCHED by default). -- Regards, vatsa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
