Messages in this thread | | | Date | Mon, 28 Nov 2011 22:43:24 +0100 | From | Michal Hocko <> | Subject | Re: [REGRESSION] [Linux 3.2] top/htop and all other CPU usage metering applications has gone crackers |
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On Mon 28-11-11 22:41:25, Michal Hocko wrote: > Hi, > > On Mon 28-11-11 21:19:26, Rafael J. Wysocki wrote: > > On Monday, November 28, 2011, Tino Keitel wrote: > > > On Sun, Nov 27, 2011 at 12:45:57 +0100, Rafael J. Wysocki wrote: > > > > On Sunday, November 27, 2011, Tino Keitel wrote: > > > > > On Thu, Nov 24, 2011 at 21:05:53 +0100, Tino Keitel wrote: > > > > > > On Thu, Nov 24, 2011 at 10:30:15 +0000, Artem S. Tashkinov wrote: > > > > > > > Hello, > > > > > > > > > > > > > > I'd like to report a weird regression in Linux 3.2 (running rc3 now) - all CPU metering applications have gone terribly mad > > > > > > > under this kernel: > > > > > > > > > > > > I get the same using top, htop and the gnome system monitor with kernel > > > > > > 3.2 on a Sandy Bridge quad core box, running Debian unstable. > > > > > > > > > > I just tested 3.2-rc2, and see the same bug. > > > > > > > > I'm seeing that too on one of my test boxes, but not all the time > > > > (i.e. there are periods in which the readings are correct). The other boxes > > > > I've tested with 3.2-rc are fine in that respect. > > > > > > > > Also, it seems that it shows 100%-(real load) when it is wrong. So, it looks > > > > like there's an overflow somewhere in the CPU load measuring code, at least > > > > on some CPUs. > > > > > > Hi, > > > > > > I reverted this commit and so far it looks good: > > > > > > commit a25cac5198d4ff2842ccca63b423962848ad24b2 > > > Author: Michal Hocko <mhocko@suse.cz> > > > Date: Wed Aug 24 09:40:25 2011 +0200 > > > > > > proc: Consider NO_HZ when printing idle and iowait times > > > > > > I'll report back tomorrow how the kernel behaves. > > > > Hmm. Michal, can you have a look at that, please? > > Hmm, my testing didn't show anything like that. Could you post > cat /proc/stat collected every second during 30s or so? > > Here is the output of my run with 3.2.0-rc3-00004-gdd38d29 and the attached config: > for i in `seq 30`; > do > cat /proc/stat > `date +'%s'` > sleep 1 > done > export old_user=0 old_nice=0 old_sys=0 old_idle=0 old_iowait=0; > grep cpu0 * | while read cpu user nice sys idle iowait rest; > do > echo $cpu $(($user-$old_user)) $(($nice-$old_nice)) $(($sys-$old_sys)) $(($idle-$old_idle)) $(($iowait-$old_iowait)) > old_user=$user old_nice=$nice old_sys=$sys old_idle=$idle old_iowait=$iowait > done > > Mostly no workload (idle desktop) - few seconds of bosy loop: > 1322516060:cpu0 621150 1978 148367 299773 196163 > 1322516061:cpu0 4 0 3 92 0 > 1322516062:cpu0 16 0 9 79 0 > 1322516063:cpu0 0 0 0 97 0 [...]
Forgot to add, but cpu1 looks similar 1322516060:cpu1 641344 832 137307 132871 44144 1322516061:cpu1 4 0 4 92 0 1322516062:cpu1 19 0 11 74 0 1322516063:cpu1 2 0 2 96 0 1322516064:cpu1 7 0 4 89 0 1322516065:cpu1 0 0 0 97 0 1322516066:cpu1 2 0 3 88 6 1322516067:cpu1 59 0 1 40 0 1322516068:cpu1 101 0 0 0 0 1322516069:cpu1 100 0 0 0 0 1322516070:cpu1 1 0 1 96 0 1322516071:cpu1 1 0 3 90 7 1322516072:cpu1 2 0 0 97 0 1322516073:cpu1 1 0 1 98 0 1322516074:cpu1 1 0 3 97 0 1322516075:cpu1 0 0 0 98 0 1322516076:cpu1 2 0 1 98 0 1322516077:cpu1 1 0 2 98 0 1322516078:cpu1 0 0 1 99 0 1322516079:cpu1 1 0 2 99 0 1322516080:cpu1 0 0 1 98 0 1322516081:cpu1 1 0 1 98 0 1322516082:cpu1 1 0 2 98 0 1322516083:cpu1 0 0 1 99 0 1322516084:cpu1 2 0 1 98 0 1322516085:cpu1 1 0 2 97 0 1322516086:cpu1 1 0 0 99 0 1322516087:cpu1 0 0 2 97 0 1322516088:cpu1 2 0 2 98 0 1322516089:cpu1 1 0 1 97 0
-- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic
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