From: Peter Zijlstra <peterz@infradead.org>
To: Uladzislau Rezki <urezki@gmail.com>
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: Mon, 13 Feb 2017 14:51:49 +0100 [thread overview]
Message-ID: <20170213135149.GQ6515@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <CA+KHdyUow0R_0syySvazFRe2gM2AnZFmCqH_x+KD=yBAOew6Xw@mail.gmail.com>
On Thu, Feb 09, 2017 at 07:54:05PM +0100, Uladzislau Rezki wrote:
> > 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".
So that is useful information that should have been in the Changelog.
OK, can you respin this patch with adjusted Changelog and taking Mike's
feedback?
Also, I worry about the effects of this on !PREEMPT kernels, the first
hunk (which explicitly states is about latency) should be under
CONFIG_PREEMPT to match the similar case we already have in
detach_tasks().
But your second hunk, which ignores the actual load of tasks in favour
of just moving _something_ already, is utterly dangerous if not coupled
with these two other conditions, so arguably that too should be under
CONFIG_PREEMPT.
next prev parent reply other threads:[~2017-02-13 13:51 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
2017-02-13 13:51 ` Peter Zijlstra [this message]
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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