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From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Byungchul Park <byungchul.park@lge.com>,
	Chris Metcalf <cmetcalf@ezchip.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Luiz Capitulino <lcapitulino@redhat.com>,
	Christoph Lameter <cl@linux.com>,
	"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
	Mike Galbraith <efault@gmx.de>, Rik van Riel <riel@redhat.com>
Subject: Re: [RFC PATCH 0/4] sched: Improve cpu load accounting with nohz
Date: Thu, 14 Jan 2016 22:23:46 +0000	[thread overview]
Message-ID: <56981FF2.6030700@arm.com> (raw)
In-Reply-To: <20160114212704.GJ6357@twins.programming.kicks-ass.net>

On 01/14/2016 09:27 PM, Peter Zijlstra wrote:
> On Thu, Jan 14, 2016 at 09:19:00PM +0000, Dietmar Eggemann wrote:
>> @@ -4346,7 +4346,10 @@ static void __update_cpu_load(struct rq *this_rq, unsigned long this_load,
>>
>>                  /* scale is effectively 1 << i now, and >> i divides by scale */
>>
>> -               old_load = this_rq->cpu_load[i] - tickless_load;
>> +               if (this_rq->cpu_load[i] > tickless_load)
>> +                       old_load = this_rq->cpu_load[i] - tickless_load;
>> +               else
>> +                       old_load = 0;
>
> Yeah, yuck. That'd go bad quick.
>

... because I set it to 0? But after the decay function we add
tickless_load to old_load. Maybe in case tickless_load >
this_rq->cpu_load[i] we decay this_rq->cpu_load[i] and do not add
tickless_load afterwards.


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  reply	other threads:[~2016-01-14 22:27 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-13 16:01 [RFC PATCH 0/4] sched: Improve cpu load accounting with nohz Frederic Weisbecker
2016-01-13 16:01 ` [PATCH 1/4] sched: Don't account tickless CPU load on tick Frederic Weisbecker
2016-01-19 13:08   ` Peter Zijlstra
2016-01-19 16:22     ` Frederic Weisbecker
2016-01-19 18:56       ` Peter Zijlstra
2016-01-19 22:33         ` Frederic Weisbecker
2016-01-20  5:43           ` Byungchul Park
2016-01-20 10:26             ` Byungchul Park
2016-01-28 16:01               ` Frederic Weisbecker
2016-01-29  9:50                 ` Peter Zijlstra
2016-02-01 10:05                   ` Byungchul Park
2016-02-01 10:09                     ` [PATCH] sched: calculate sched_clock_cpu without tick handling during nohz Byungchul Park
2016-02-01 10:34                     ` [PATCH 1/4] sched: Don't account tickless CPU load on tick Peter Zijlstra
2016-02-01 23:51                       ` Byungchul Park
2016-02-02  0:50                       ` Byungchul Park
2016-02-01  6:33               ` Byungchul Park
2016-01-20  8:42     ` Thomas Gleixner
2016-01-20 17:36       ` Frederic Weisbecker
2016-01-22  8:40       ` Byungchul Park
2016-01-13 16:01 ` [PATCH 2/4] sched: Consolidate nohz CPU load update code Frederic Weisbecker
2016-01-14  2:30   ` Byungchul Park
2016-01-19 13:13     ` Peter Zijlstra
2016-01-20  0:51       ` Byungchul Park
2016-01-14  5:18   ` Byungchul Park
2016-01-19 13:13     ` Peter Zijlstra
2016-01-19 16:49     ` Frederic Weisbecker
2016-01-20  1:41       ` Byungchul Park
2016-02-29 11:14   ` [tip:sched/core] sched/fair: " tip-bot for Frederic Weisbecker
2016-01-13 16:01 ` [RFC PATCH 3/4] sched: Move cpu load stats functions above fair queue callbacks Frederic Weisbecker
2016-01-13 16:01 ` [RFC PATCH 4/4] sched: Upload nohz full CPU load on task enqueue/dequeue Frederic Weisbecker
2016-01-19 13:17   ` Peter Zijlstra
2016-01-19 17:03     ` Frederic Weisbecker
2016-01-20  9:09       ` Peter Zijlstra
2016-01-20 14:54         ` Frederic Weisbecker
2016-01-20 15:11           ` Thomas Gleixner
2016-01-20 15:19             ` Christoph Lameter
2016-01-20 16:52               ` Frederic Weisbecker
2016-01-20 16:45             ` Frederic Weisbecker
2016-01-20 16:56           ` Peter Zijlstra
2016-01-20 17:21             ` Frederic Weisbecker
2016-01-20 18:25               ` Peter Zijlstra
2016-01-21 13:25                 ` Frederic Weisbecker
2016-01-20  9:03   ` Thomas Gleixner
2016-01-20 14:31     ` Frederic Weisbecker
2016-01-20 14:43       ` Thomas Gleixner
2016-01-20 16:40         ` Frederic Weisbecker
2016-01-20 16:42           ` Christoph Lameter
2016-01-20 16:47             ` Frederic Weisbecker
2016-01-14 21:19 ` [RFC PATCH 0/4] sched: Improve cpu load accounting with nohz Dietmar Eggemann
2016-01-14 21:27   ` Peter Zijlstra
2016-01-14 22:23     ` Dietmar Eggemann [this message]
2016-01-15  7:07       ` Byungchul Park
2016-01-15 16:56         ` Dietmar Eggemann
2016-01-18  0:23           ` Byungchul Park
2016-01-19 13:04           ` Peter Zijlstra
2016-01-20  0:48             ` Byungchul Park
2016-01-20 13:04               ` Dietmar Eggemann
2016-02-29 11:14         ` [tip:sched/core] sched/fair: Avoid using decay_load_missed() with a negative value tip-bot for Byungchul Park

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