linux-kernel - Re: v4.18-rc1 on droid 4: very bad CPU performance

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Date:   Mon, 25 Jun 2018 11:49:49 +0200
From:   Pavel Machek <pavel@....cz>
To:     Tony Lindgren <tony@...mide.com>
Cc:     kernel list <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-omap@...r.kernel.org, sre@...nel.org, nekit1000@...il.com,
        mpartap@....net, merlijn@...zup.org
Subject: Re: v4.18-rc1 on droid 4: very bad CPU performance

Hi!

> > > V4.18 is slower than it should be.
> > > 
> > > user@...uan:~$ time cat /dev/urandom | head -c 10000000 |  bzip2 -9 -
> > > | wc -c
> > > 10044291
> > > 52.73user 2.40system 61.53 (1m1.534s) elapsed 89.60%CPU
> > > user@...uan:~$ uname -a
> > > Linux devuan 4.18.0-rc1-87964-gfa19934-dirty #743 SMP Sun Jun 17
> > > 19:26:37 CEST 2018 armv7l GNU/Linux
> > > 
> > > That bzip should take 12 seconds, not minute.
> > > 
> > > Any ideas? Do you see it, too?
> > 
> > I've noticed firefox is super slow.. Git bisect time?
> 
> Hmm not happening for me at least on duovero and droid4,
> I'm getting about 20s for v4.17 and v4.18-rc1.

Something weird is going on here. My notes say it should be 12
seconds.

It is indeed 20 seconds for v4.17, but it is 12 seconds in v4.14.

v4.14 is:
# CONFIG_CPU_FREQ is not set
CONFIG_CPU_IDLE=y
# CONFIG_CPU_IDLE_GOV_LADDER is not set
CONFIG_CPU_IDLE_GOV_MENU=y
# CONFIG_ARM_CPUIDLE is not set

In v4.18, I have:

CONFIG_CPU_FREQ=y
CONFIG_CPU_FREQ_GOV_ATTR_SET=y
CONFIG_CPU_FREQ_GOV_COMMON=y
CONFIG_CPU_FREQ_STAT=y
CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND=y

CONFIG_CPU_IDLE=y
CONFIG_CPU_IDLE_GOV_MENU=y
CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED=y


									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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