From: Ingo Molnar <mingo@kernel.org>
To: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Borislav Petkov <bp@alien8.de>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH -tip] sched/cputime: do not scale when utime == 0
Date: Wed, 4 Sep 2013 14:33:50 +0200 [thread overview]
Message-ID: <20130904123350.GA9773@gmail.com> (raw)
In-Reply-To: <20130904120857.GB2564@redhat.com>
* Stanislaw Gruszka <sgruszka@redhat.com> wrote:
> scale_stime() silently assumes that stime < rtime, otherwise when
> stime == rtime and both values are big (operations on them do not fit
> in 32 bits), the resulting scaling stime can be bigger than rtime.
> In consequence utime = rtime - stime results in negative value.
Please also describe observed/expected symptoms of this bug in apps, so
that we can later on redirect bugreporters to this fix and filter out new
symptoms (if any).
Thanks,
Ingo
next prev parent reply other threads:[~2013-09-04 12:33 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-20 11:14 [sched next] overflowed cpu time for kernel threads in /proc/PID/stat Sergey Senozhatsky
2013-08-20 15:15 ` Frederic Weisbecker
2013-08-20 15:35 ` Sergey Senozhatsky
2013-08-20 15:42 ` Frederic Weisbecker
2013-08-20 15:53 ` Sergey Senozhatsky
2013-08-20 18:48 ` Sergey Senozhatsky
2013-08-21 15:39 ` Sergey Senozhatsky
2013-08-30 23:04 ` Frederic Weisbecker
2013-08-31 19:01 ` Sergey Senozhatsky
2013-09-08 10:56 ` Frederic Weisbecker
2013-09-08 10:59 ` Frederic Weisbecker
2013-09-02 12:28 ` Sergey Senozhatsky
2013-09-02 13:07 ` Frederic Weisbecker
2013-09-02 13:39 ` Sergey Senozhatsky
2013-09-02 13:50 ` Stanislaw Gruszka
2013-09-02 14:00 ` Sergey Senozhatsky
2013-09-03 8:43 ` Stanislaw Gruszka
2013-09-03 9:33 ` Sergey Senozhatsky
2013-09-03 13:15 ` Sergey Senozhatsky
2013-09-03 18:09 ` Sergey Senozhatsky
2013-09-03 18:32 ` Ingo Molnar
2013-09-04 12:08 ` [PATCH -tip] sched/cputime: do not scale when utime == 0 Stanislaw Gruszka
2013-09-04 12:33 ` Ingo Molnar [this message]
2013-09-04 13:16 ` [PATCH -tip v2] " Stanislaw Gruszka
2013-09-04 14:31 ` Ingo Molnar
2013-09-04 14:37 ` [tip:timers/urgent] sched/cputime: Do " tip-bot for Stanislaw Gruszka
2013-09-04 15:35 ` Frederic Weisbecker
2013-09-02 14:13 ` [sched next] overflowed cpu time for kernel threads in /proc/PID/stat Frederic Weisbecker
2013-09-02 14:24 ` Sergey Senozhatsky
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