Re: [PATCH] sched/cputime: Fix steal time accounting vs. cpu hotplug

2016-03-04 Thread Rik van Riel
On Fri, 2016-03-04 at 15:59 +0100, Thomas Gleixner wrote: > On cpu hotplug the steal time accounting can keep a stale rq- > >prev_steal_time > value over cpu down and up. So after the cpu comes up again the delta > calculation in steal_account_process_tick() wreckages itself due to > the > unsigned

[PATCH] sched/cputime: Fix steal time accounting vs. cpu hotplug

2016-03-04 Thread Thomas Gleixner
On cpu hotplug the steal time accounting can keep a stale rq->prev_steal_time value over cpu down and up. So after the cpu comes up again the delta calculation in steal_account_process_tick() wreckages itself due to the unsigned math: u64 steal = paravirt_steal_clock(smp_processor_id());