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From: "Doug Smythies" <dsmythies@telus.net>
To: "'Rafael J. Wysocki'" <rafael@kernel.org>,
	"'Thomas Ilsche'" <thomas.ilsche@tu-dresden.de>
Cc: "'Linux PM'" <linux-pm@vger.kernel.org>,
	"'Peter Zijlstra'" <peterz@infradead.org>,
	"'Frederic Weisbecker'" <fweisbec@gmail.com>,
	"'Thomas Gleixner'" <tglx@linutronix.de>,
	"'Paul McKenney'" <paulmck@linux.vnet.ibm.com>,
	"'Rik van Riel'" <riel@surriel.com>,
	"'Aubrey Li'" <aubrey.li@linux.intel.com>,
	"'Mike Galbraith'" <mgalbraith@suse.de>,
	"'LKML'" <linux-kernel@vger.kernel.org>,
	"Doug Smythies" <dsmythies@telus.net>
Subject: RE: [RFT][PATCH v7 5/8] cpuidle: Return nohz hint from cpuidle_select()
Date: Thu, 22 Mar 2018 08:41:54 -0700
Message-ID: <000401d3c1f4$5043adb0$f0cb0910$@net> (raw)
In-Reply-To: ysl4eqMKwFfdwytebe4RNZ

On 2018.03.21 23:25 Doug Smythies wrote:
> On 2018.03.21 15:15 Rafael J. Wysocki wrote:
>> On Wed, Mar 21, 2018 at 6:59 PM, Thomas Ilsche wrote:
>>> On 2018-03-21 15:36, Rafael J. Wysocki wrote:
>>>>
>>>> So please disregard this one entirely and take the v7.2 replacement
>>>> instead of it:https://patchwork.kernel.org/patch/10299429/
>>>>
>>>> The current versions (including the above) is in the git branch at
>>>>
>>>>   git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git \
>>>>   idle-loop-v7.2
>>>
>>> With v7.2 (tested on SKL-SP from git) I see similar behavior in idle
>>> as with v5: several cores which just keep the sched tick enabled.
>>> Worse yet, some go only in C1 (not even C1E!?) despite sleeping the
>>> full sched tick.
>>> The resulting power consumption is ~105 W instead of ~ 70 W.
>>>
>>> https://wwwpub.zih.tu-dresden.de/~tilsche/powernightmares/v7_2_skl_sp_idle.png
>>>
>>> I have briefly ran v7 and I believe it was also affected.

I am not seeing any issues at all with V7.

>>
>> Then it looks like menu_select() stubbornly thinks that the idle
>> duration will be within the tick boundary on those cores.
>> 
>> That may be because the bumping up of the correction factor in
>> menu_reflect() is too conservative or it may be necessary to do
>> something radical to measured_us in menu_update() in case of a tick
>> wakeup combined with a large next_timer_us value.
>>
>> For starters, please see if the attached patch (on top of the
>> idle-loop-v7.2 git branch) changes this behavior in any way.
>
> O.K. I am seeing some weirdness.
> On my system with both V7.2 and V7.2 plus this patch, I observe
> A spike in Idle State 1 residency every 34+ minutes. And slightly
> higher average idle power than before.
> (I might not have done V7 idle tests long enough).

I re-did the idle test on V7, and for longer.
It is great.
See line added to the idle graph for V7.2+:

http://fast.smythies.com/rjw_v72p_v7_idle.png

>
> It can be seen in the frequency sweep I did earlier today, with V7.2:
>
> http://fast.smythies.com/rjw_freq_sweep_72_combined.png
>
> Despite the note on the graph that says it might be real, I don't think
> it is (I forgot to delete the note).
>
> With V7.2+ sometimes the event occurs at 17 minute intervals.
> Here is a idle graph (for reference: we have seen idle package power
> pretty steady at ~3.7 watts before).

Now shown on the new graph. Link above.

>
> http://fast.smythies.com/rjw_v72p_idle.png

... Doug
 

  parent reply index

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-20 15:12 [RFT][PATCH v7 0/8] sched/cpuidle: Idle loop rework Rafael J. Wysocki
2018-03-20 15:13 ` [RFT][PATCH v7 1/8] time: tick-sched: Reorganize idle tick management code Rafael J. Wysocki
2018-03-20 15:15 ` [RFT][PATCH v7 2/8] sched: idle: Do not stop the tick upfront in the idle loop Rafael J. Wysocki
2018-03-20 15:15 ` [RFT][PATCH v7 3/8] " Rafael J. Wysocki
2018-03-20 18:00   ` [Correction][RFT][PATCH v7 3/8] sched: idle: Do not stop the tick before cpuidle_idle_call() Rafael J. Wysocki
2018-03-20 15:16 ` [RFT][PATCH v7 4/8] jiffies: Introduce USER_TICK_USEC and redefine TICK_USEC Rafael J. Wysocki
2018-03-20 15:45 ` [RFT][PATCH v7 5/8] cpuidle: Return nohz hint from cpuidle_select() Rafael J. Wysocki
2018-03-21  6:48   ` [RFT][PATCH v7.1 " Rafael J. Wysocki
2018-03-21 11:52     ` Rafael J. Wysocki
2018-03-21 13:03   ` [RFT][PATCH v7.2 " Rafael J. Wysocki
2018-03-21 14:36   ` [RFT][PATCH v7 " Rafael J. Wysocki
2018-03-21 17:59     ` Thomas Ilsche
2018-03-21 22:15       ` Rafael J. Wysocki
2018-03-22 13:18         ` Thomas Ilsche
2018-03-22 17:23           ` Rafael J. Wysocki
2018-03-22  6:24       ` Doug Smythies
2018-03-22 15:41       ` Doug Smythies [this message]
2018-03-22 17:21         ` Rafael J. Wysocki
2018-03-21 18:23     ` Doug Smythies
2018-03-22 17:40   ` [RFT][PATCH v7.3 " Rafael J. Wysocki
2018-03-28  9:14     ` Thomas Ilsche
2018-03-30  9:39       ` Rafael J. Wysocki
2018-04-10 15:22         ` Thomas Ilsche
2018-03-22 20:46   ` Doug Smythies
2018-03-20 15:45 ` [RFT][PATCH v7 6/8] sched: idle: Select idle state before stopping the tick Rafael J. Wysocki
2018-03-27 21:50   ` Thomas Ilsche
2018-03-27 22:10     ` Rafael J. Wysocki
2018-03-28  8:13       ` Rafael J. Wysocki
2018-03-28  8:38         ` Thomas Ilsche
2018-03-28 10:37           ` Rafael J. Wysocki
2018-03-28 10:56             ` Rafael J. Wysocki
2018-03-28 15:15               ` Thomas Ilsche
2018-03-28 20:41               ` Doug Smythies
2018-03-28 23:11                 ` Rafael J. Wysocki
2018-03-20 15:46 ` [RFT][PATCH v7 7/8] cpuidle: menu: Refine idle state selection for running tick Rafael J. Wysocki
2018-03-20 15:47 ` [RFT][PATCH v7 8/8] cpuidle: menu: Avoid selecting shallow states with stopped tick Rafael J. Wysocki
2018-03-20 17:52 ` [RFT][PATCH v7 3/8] sched: idle: Do not stop the tick upfront in the idle loop Doug Smythies
2018-03-20 18:01   ` Rafael J. Wysocki
2018-03-21 12:31 ` [RFT][PATCH v7 0/8] sched/cpuidle: Idle loop rework Rik van Riel
2018-03-21 13:55   ` Rafael J. Wysocki
2018-03-21 14:53     ` Rik van Riel

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