On Mon, Jul 16, 2018 at 03:37:51PM +0200, Peter Zijlstra wrote: > On Sun, Jul 15, 2018 at 04:36:17PM -0700, tip-bot for Xunlei Pang wrote: > > Commit-ID: 8d4c00dc38a8aa30dae8402955e55e7b34e74bc8 > > Gitweb: https://git.kernel.org/tip/8d4c00dc38a8aa30dae8402955e55e7b34e74bc8 > > Author: Xunlei Pang <xlpang@xxxxxxxxxxxxxxxxx> > > AuthorDate: Mon, 9 Jul 2018 22:58:43 +0800 > > Committer: Ingo Molnar <mingo@xxxxxxxxxx> > > CommitDate: Mon, 16 Jul 2018 00:28:31 +0200 > > > > sched/cputime: Ensure accurate utime and stime ratio in cputime_adjust() > > > > If users access "/proc/pid/stat", the utime and stime ratio in the > > current SAMPLE period are excepted, but currently cputime_adjust() > > always calculates with the ratio of the WHOLE lifetime of the process. > > > > This results in inaccurate utime and stime in "/proc/pid/stat". For > > example, a process runs for a while with "50% usr, 0% sys", then > > followed by "100% sys". For later while, the following is excepted: > > > > 0.0 usr, 100.0 sys > > > > but we get: > > > > 10.0 usr, 90.0 sys > > > > This patch uses the accurate ratio in cputime_adjust() to address the > > issue. A new 'task_cputime' type field is added in prev_cputime to record > > previous 'task_cputime' so that we can get the elapsed times as the accurate > > ratio. > > Ingo, please make this one go away. I still have no idae what the > problem is and I've not had time to reverse engineer the patch. > > The previous (v1) Changelog was a pile of incoherent rambling and the > above doesn't explain anything much. > > I want a clear description of the problem and a coherent explanation of > the proposed solution without having to reverse engineer the actual > patch. I must confess I'm having trouble to understand what the real problem is. -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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