From: Uladzislau Rezki <urezki@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Uladzislau 2 Rezki <uladzislau2.rezki@sonymobile.com>
Subject: Re: [RFC,v2 3/3] sched: ignore task_h_load for CPU_NEWLY_IDLE
Date: Thu, 9 Feb 2017 19:54:05 +0100 [thread overview]
Message-ID: <CA+KHdyUow0R_0syySvazFRe2gM2AnZFmCqH_x+KD=yBAOew6Xw@mail.gmail.com> (raw)
In-Reply-To: <20170209122218.GE6500@twins.programming.kicks-ass.net>
On Thu, Feb 9, 2017 at 1:22 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Wed, Feb 08, 2017 at 09:43:29AM +0100, Uladzislau Rezki wrote:
>> From: Uladzislau 2 Rezki <uladzislau2.rezki@sonymobile.com>
>>
>> A load balancer calculates imbalance factor for particular shed
>> domain and tries to steal up the prescribed amount of weighted load.
>> However, a small imbalance factor would sometimes prevent us from
>> stealing any tasks at all. When a CPU is newly idle, it should
>> steal first task which passes a migration criteria.
>>
>
> So ideally we'd reduce the number of special cases instead of increase
> them.
>
I agree.
>
> Does this patch make an actual difference, if so how much and with
> what workload?
>
Yes, it does. I see a slight improvement when it comes to frame drops
(in my case drops per/two seconds). Basically a test case is left finger
swipe on the display (21 times, duration is 2 seconds + 1 second sleep
between iterations):
0 Framedrops: 7 5
1 Framedrops: 5 3
2 Framedrops: 8 5
3 Framedrops: 4 5
4 Framedrops: 3 3
5 Framedrops: 6 4
6 Framedrops: 3 2
7 Framedrops: 3 4
8 Framedrops: 5 3
9 Framedrops: 3 3
10 Framedrops: 7 4
11 Framedrops: 3 4
12 Framedrops: 3 3
13 Framedrops: 3 3
14 Framedrops: 3 5
15 Framedrops: 7 3
16 Framedrops: 5 3
17 Framedrops: 3 2
18 Framedrops: 5 3
19 Framedrops: 4 3
20 Framedrops: 3 2
max is 8 vs 5; min is 2 vs 3.
As for applied load, it is not significant and i would say is "light".
--
Uladzislau Rezki
next prev parent reply other threads:[~2017-02-09 19:01 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-08 8:43 [RFC,v2 1/3] sched: set loop_max after rq lock is taken Uladzislau Rezki
2017-02-08 8:43 ` [RFC,v2 2/3] sched: set number of iterations to h_nr_running Uladzislau Rezki
2017-02-09 12:20 ` Peter Zijlstra
2017-02-09 18:59 ` Uladzislau Rezki
2017-02-08 8:43 ` [RFC,v2 3/3] sched: ignore task_h_load for CPU_NEWLY_IDLE Uladzislau Rezki
2017-02-08 9:19 ` Mike Galbraith
2017-02-09 10:12 ` Uladzislau Rezki
2017-02-09 12:22 ` Peter Zijlstra
2017-02-09 18:54 ` Uladzislau Rezki [this message]
2017-02-13 13:51 ` Peter Zijlstra
2017-02-13 17:17 ` Uladzislau Rezki
2017-02-14 18:28 ` Uladzislau Rezki
2017-02-15 18:58 ` Dietmar Eggemann
2017-02-16 11:20 ` Uladzislau Rezki
2017-03-08 15:35 ` Uladzislau Rezki
2017-02-09 12:14 ` [RFC,v2 1/3] sched: set loop_max after rq lock is taken Peter Zijlstra
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