Messages in this thread | | | From | Mac Lin <> | Date | Sat, 27 Aug 2016 23:13:43 +0800 | Subject | Re: Random abnormal high CPU sys usage related to timer |
| |
Hi Vegard, Thanks for the prompt response. The commit is introduced since 4.6, but the issue can be reproduced at 3.10 (earliest I have ever test). And testing on buildroot+4.7 with the commit reverted, the issue still happen.
In fact, I did a test that ran a script that keep increase a counter for 10 seconds on the same CPU. If I ran 2 of it, the number is half of running 1. But if I ran it while the issue happened, the counter reported is around the same value as the 1 process case. So I doubt that it might be an issue of reported number.
Is there other way to ensure the CPU is "really" doing something?
x=0 trap 'echo x=$x;exit 1' SIGHUP SIGINT SIGTERM while : ; do x=$(($x+1)); # echo $x; done
On Sat, Aug 27, 2016 at 5:12 AM, Vegard Nossum <vegard.nossum@gmail.com> wrote: > On 26 August 2016 at 19:10, Mac Lin <mkl0301@gmail.com> wrote: >> We were having issue with our userspace application which >> __sometimes__ result in high CPU sys usage at each execution. The high >> sys CPU usage persist until the application is killed. > [...] >> Googling found one issue that seems related, but no further action. > > Was it this one? https://lkml.org/lkml/2016/8/23/360 > > If so you may try to revert commit ff9a9b4c4334 ("sched, time: Switch > VIRT_CPU_ACCOUNTING_GEN to jiffy granularity") to see if it helps. > > > Vegard
| |