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Date: Sat, 31 Aug 2013 01:04:04 +0200 From: Frederic Weisbecker <fweisbec@...il.com> To: Sergey Senozhatsky <sergey.senozhatsky@...il.com> Cc: Stanislaw Gruszka <sgruszka@...hat.com>, Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>, Borislav Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org Subject: Re: [sched next] overflowed cpu time for kernel threads in /proc/PID/stat On Wed, Aug 21, 2013 at 06:39:57PM +0300, Sergey Senozhatsky wrote: > On (08/20/13 17:42), Frederic Weisbecker wrote: > > On Tue, Aug 20, 2013 at 06:35:50PM +0300, Sergey Senozhatsky wrote: > > > On (08/20/13 17:15), Frederic Weisbecker wrote: > > > > On Tue, Aug 20, 2013 at 02:14:26PM +0300, Sergey Senozhatsky wrote: > > > > Hello, > > > > > > > > Please upload your config. > > > > > > > > I'm adding Stanislaw in Cc in case it relates to cputime scaling. > > > > > > > > > > please find attached. > > > > > > -ss > > > > > # > > > # CPU/Task time and stats accounting > > > # > > > CONFIG_VIRT_CPU_ACCOUNTING=y > > > CONFIG_VIRT_CPU_ACCOUNTING_GEN=y > > > > So it happens with full dynticks cputime accounting. > > How reproducable is this? Does it always happen? > > Does it happen with CONFIG_TICK_CPU_ACCOUNTING as well? (you'll > > need to deactivate full dynticks.) > > in cputime_adjust() `stime' is greater than `rtime', so `utime = rtime - stime' > sets wrong value. But stime should always be below rtime due to the calculation done by scale_stime() which roughly sums up to: stime = (stime / stime + utime) * rtime So this shouldn't happen. I couldn't manage to reproduce it though. Can you still trigger it with latest -next? Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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