From: Peter Zijlstra <peterz@infradead.org>
To: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: linux-kernel@vger.kernel.org,
Fernando Luis Vazquez Cao <fernando_b1@lab.ntt.co.jp>,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
Frederic Weisbecker <fweisbec@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Arjan van de Ven <arjan@linux.intel.com>,
Oleg Nesterov <oleg@redhat.com>,
Preeti U Murthy <preeti@linux.vnet.ibm.com>,
Denys Vlasenko <vda.linux@googlemail.com>,
stable@vger.kernel.org
Subject: Re: [PATCH 1/2] nohz: stop updating sleep stats from get_cpu_{idle,iowait}_time_us()
Date: Tue, 15 Apr 2014 10:48:54 +0200 [thread overview]
Message-ID: <20140415084854.GL11096@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <53466027.3040705@jp.fujitsu.com>
On Thu, Apr 10, 2014 at 06:11:03PM +0900, Hidetoshi Seto wrote:
> - if (ts->idle_active) {
> - delta = ktime_sub(now, ts->idle_entrytime);
> - if (nr_iowait_cpu(cpu) > 0)
> - ts->iowait_sleeptime = ktime_add(ts->iowait_sleeptime, delta);
> - else
> - ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
> - ts->idle_entrytime = now;
> - }
> -
> - if (last_update_time)
> - *last_update_time = ktime_to_us(now);
> -
> -}
> -
> -static void tick_nohz_stop_idle(struct tick_sched *ts, ktime_t now)
> -{
> - update_ts_time_stats(smp_processor_id(), ts, now, NULL);
> + /* Updates the per cpu time idle statistics counters */
> + delta = ktime_sub(now, ts->idle_entrytime);
> + if (nr_iowait_cpu(smp_processor_id()) > 0)
Now I know the old code also uses nr_iowait_cpu(), but that function is
crackbrained. This cannot possibly be right.
Anything using nr_iowait_cpu() is broken beyond repair.
next prev parent reply other threads:[~2014-04-15 8:48 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-10 9:07 [PATCH v3 0/2] nohz: fix idle accounting in NO_HZ kernels Hidetoshi Seto
2014-04-10 9:11 ` [PATCH 1/2] nohz: stop updating sleep stats from get_cpu_{idle,iowait}_time_us() Hidetoshi Seto
2014-04-15 8:48 ` Peter Zijlstra [this message]
2014-04-15 8:49 ` Peter Zijlstra
2014-04-10 9:13 ` [PATCH 2/2] nohz: use delayed iowait accounting to avoid race on idle time stats Hidetoshi Seto
2014-04-15 10:04 ` Peter Zijlstra
2014-04-16 6:30 ` Hidetoshi Seto
2014-04-15 10:19 ` Peter Zijlstra
2014-04-16 6:33 ` Hidetoshi Seto
2014-04-16 9:36 ` Peter Zijlstra
2014-04-17 0:42 ` Hidetoshi Seto
2014-04-17 10:05 ` Peter Zijlstra
2014-04-17 10:09 ` Peter Zijlstra
2014-04-18 5:52 ` Hidetoshi Seto
2014-04-18 8:44 ` Peter Zijlstra
2014-04-15 3:11 ` [PATCH v3 0/2] nohz: fix idle accounting in NO_HZ kernels Hidetoshi Seto
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