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 <xlp...@linux.alibaba.com> > AuthorDate: Mon, 9 Jul 2018 22:58:43 +0800 > Committer: Ingo Molnar <mi...@kernel.org> > 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.
