> Subject: Re: [PATCH] cputime: fix invalid gtime > > On Thu, Sep 03, 2015 at 12:45:50AM +0000, Hiroshi Shimamoto wrote: > > From: Hiroshi Shimamoto <h-shimam...@ct.jp.nec.com> > > > > /proc/stats shows invalid gtime when the thread is running in guest. > > Why is this a problem?
In host, when I monitored cpu usage in guest I noticed that the cpu time is not stable. > > > When vtime accounting is not enabled, we cannot get a valid delta. > > Just return gtime when vtime accounting is not enabled in task_gtime(). > > But isn't other stuff then also broken, like fetch_task_cputime(). Tell > me more about why you think your patch is the right one. No, because I think vtime_snap_whence keeps VTIME_SLEEPING until vtime_accounting_enabled() returns true. Then no delta is added. > > > Before > > 10987 (qemu-kvm) S 1 10923 10923 0 -1 138428608 7521 0 90 0 3776 460 0 0 20 > > 0 24 0 11960 8090398720 151288 18446744073709551615 > 1 1 0 0 0 0 2147220671 4096 25155 18446744073709551615 0 0 -1 9 0 0 0 3554 0 > 0 0 0 0 0 0 0 0 > > It would have been helpful if you'd used a small script to take out the > right column. As is I've no clue which field to look at. Sorry for inconvenience with little explanation. I watched /proc/<pid>/stats. When guest running busy, gtime looks big number. 10987 (qemu-kvm) S ... 3554 ... 10987 (qemu-kvm) R ... 21415 ... and keep it busy. after 1 second. 10987 (qemu-kvm) R ... 21616 ... few second later, I stopped busy program on guest. The gtime back to sane value. 10987 (qemu-kvm) S ... 4084 ... thanks, Hiroshi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
