[gentoo-user] Would constant max CPU speed cause lockups?

[gentoo-user] Would constant max CPU speed cause lockups?

[Walter Dnes]

  A few years ago, I cheaped out and bought a low-powered Atom desktop
with 8 gigs of RAM.  Looking back, that was a mistake.  It would default
to 480p or at best 720p on Youtube.  But I wrote a nifty bash script
that manually put the CPU into "userspace" mode, and selected the
maximum available CPU speed.  I finally got Youtube with steady playback
at 1080p... YAY!  I'd leave it at max speed during my waking hours, and
drop it to min speed at night before going to bed.

  I saw the occasional mysterious lockups as I mentioned in recent
threads.  I wonder if pushing the CPU to max speed most of the day would
cause overheating and lockups.  I'm leaving my current, more powerfull,
machine in "conservative" mode.

  Should I stay in conservative mode?  Or forget about speed control
entirely, and let "Intel Speed Step" handle things for me?  Also, is
there a way to enable CPU throttling based on temperature?

-- 
Walter Dnes <waltdnes@waltdnes.org>
I don't run "desktop environments"; I run useful applications

Re: [gentoo-user] Would constant max CPU speed cause lockups?

[tastytea]

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On 2021-06-05 13:18-0400 "Walter Dnes" <waltdnes@waltdnes.org> wrote:

>   A few years ago, I cheaped out and bought a low-powered Atom desktop
> with 8 gigs of RAM.  Looking back, that was a mistake.  It would
> default to 480p or at best 720p on Youtube.  But I wrote a nifty bash
> script that manually put the CPU into "userspace" mode, and selected
> the maximum available CPU speed.  I finally got Youtube with steady
> playback at 1080p... YAY!  I'd leave it at max speed during my waking
> hours, and drop it to min speed at night before going to bed.
> 
>   I saw the occasional mysterious lockups as I mentioned in recent
> threads.  I wonder if pushing the CPU to max speed most of the day
> would cause overheating and lockups.  I'm leaving my current, more
> powerfull, machine in "conservative" mode.

The CPU will automatically throttle when a certain temperature is
reached. This may be the cause of the lockups.

>   Should I stay in conservative mode?  Or forget about speed control
> entirely, and let "Intel Speed Step" handle things for me?  Also, is
> there a way to enable CPU throttling based on temperature?

Have you tried ondemand mode? It ramps up the speed faster than
conservative mode and drops equally fast if there is not much to do. I
have it enabled everywhere and didn't notice any problems.

-- 
Get my PGP key with `gpg --locate-keys tastytea@tastytea.de` or at
<https://tastytea.de/tastytea.asc>.

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Re: [gentoo-user] Would constant max CPU speed cause lockups?

[Michael]

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On Saturday, 5 June 2021 18:37:26 BST tastytea wrote:
> On 2021-06-05 13:18-0400 "Walter Dnes" <waltdnes@waltdnes.org> wrote:
> >   A few years ago, I cheaped out and bought a low-powered Atom desktop
> > 
> > with 8 gigs of RAM.  Looking back, that was a mistake.  It would
> > default to 480p or at best 720p on Youtube.  But I wrote a nifty bash
> > script that manually put the CPU into "userspace" mode, and selected
> > the maximum available CPU speed.  I finally got Youtube with steady
> > playback at 1080p... YAY!  I'd leave it at max speed during my waking
> > hours, and drop it to min speed at night before going to bed.
> > 
> >   I saw the occasional mysterious lockups as I mentioned in recent
> > 
> > threads.  I wonder if pushing the CPU to max speed most of the day
> > would cause overheating and lockups.  I'm leaving my current, more
> > powerfull, machine in "conservative" mode.
> 
> The CPU will automatically throttle when a certain temperature is
> reached. This may be the cause of the lockups.
> 
> >   Should I stay in conservative mode?  Or forget about speed control
> > 
> > entirely, and let "Intel Speed Step" handle things for me?  Also, is
> > there a way to enable CPU throttling based on temperature?
> 
> Have you tried ondemand mode? It ramps up the speed faster than
> conservative mode and drops equally fast if there is not much to do. I
> have it enabled everywhere and didn't notice any problems.

If thermal throttling takes place there will be entries in dmesg and syslog to 
this effect.

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Re: [gentoo-user] Would constant max CPU speed cause lockups?

[Dottie Keogh]

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Have you ran memtest? 


Sent from Yahoo Mail for iPhone


On Saturday, June 5, 2021, 5:21 PM, Michael <confabulate@kintzios.com> wrote:

On Saturday, 5 June 2021 18:37:26 BST tastytea wrote:
> On 2021-06-05 13:18-0400 "Walter Dnes" <waltdnes@waltdnes.org> wrote:
> >  A few years ago, I cheaped out and bought a low-powered Atom desktop
> > 
> > with 8 gigs of RAM.  Looking back, that was a mistake.  It would
> > default to 480p or at best 720p on Youtube.  But I wrote a nifty bash
> > script that manually put the CPU into "userspace" mode, and selected
> > the maximum available CPU speed.  I finally got Youtube with steady
> > playback at 1080p... YAY!  I'd leave it at max speed during my waking
> > hours, and drop it to min speed at night before going to bed.
> > 
> >  I saw the occasional mysterious lockups as I mentioned in recent
> > 
> > threads.  I wonder if pushing the CPU to max speed most of the day
> > would cause overheating and lockups.  I'm leaving my current, more
> > powerfull, machine in "conservative" mode.
> 
> The CPU will automatically throttle when a certain temperature is
> reached. This may be the cause of the lockups.
> 
> >  Should I stay in conservative mode?  Or forget about speed control
> > 
> > entirely, and let "Intel Speed Step" handle things for me?  Also, is
> > there a way to enable CPU throttling based on temperature?
> 
> Have you tried ondemand mode? It ramps up the speed faster than
> conservative mode and drops equally fast if there is not much to do. I
> have it enabled everywhere and didn't notice any problems.

If thermal throttling takes place there will be entries in dmesg and syslog to 
this effect.



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Re: [gentoo-user] Would constant max CPU speed cause lockups?

[Frank Steinmetzger]

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Am Sat, Jun 05, 2021 at 01:18:15PM -0400 schrieb Walter Dnes:
>   A few years ago, I cheaped out and bought a low-powered Atom desktop
> with 8 gigs of RAM.  Looking back, that was a mistake.  It would default
> to 480p or at best 720p on Youtube.  But I wrote a nifty bash script
> that manually put the CPU into "userspace" mode, and selected the
> maximum available CPU speed.  I finally got Youtube with steady playback
> at 1080p... YAY!

OT, but an input to this aspect:
in-browser playback has always been a lackluster for me. It gobbles up CPU
cycles and makes the fans spin. Therefore by now it’s been engraved into my
muscle memory to copy the URL, download it and play it with
$FAVORITE_VIDEO_PLAYER.

I had a go at my Eeepc Atom netbook a few months back to see whether I could
use it as a little home server for Nextcloud and the likes. I noticed that
it drew 14 W from the socket at idle. And its performance was actually much
worse than my raspi’s (which suckles maybe 4 W). So I stowed it for good.
Pity, the haptic was not bad, but that’s the circle of life.

-- 
Grüße | Greetings | Qapla’
Please do not share anything from, with or about me on any social network.

If your laundry just wouldn’t become white,
may be that’s because it is coloured.

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Re: [gentoo-user] Would constant max CPU speed cause lockups?

[Manuel McLure]

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On Sat, Jun 5, 2021 at 10:18 AM Walter Dnes <waltdnes@waltdnes.org> wrote:

>   A few years ago, I cheaped out and bought a low-powered Atom desktop
> with 8 gigs of RAM.  Looking back, that was a mistake.  It would default
> to 480p or at best 720p on Youtube.  But I wrote a nifty bash script
> that manually put the CPU into "userspace" mode, and selected the
> maximum available CPU speed.  I finally got Youtube with steady playback
> at 1080p... YAY!  I'd leave it at max speed during my waking hours, and
> drop it to min speed at night before going to bed.
>
>   I saw the occasional mysterious lockups as I mentioned in recent
> threads.  I wonder if pushing the CPU to max speed most of the day would
> cause overheating and lockups.  I'm leaving my current, more powerfull,
> machine in "conservative" mode.
>
>   Should I stay in conservative mode?  Or forget about speed control
> entirely, and let "Intel Speed Step" handle things for me?  Also, is
> there a way to enable CPU throttling based on temperature?
>
>
Depending on the specific generation of Atom/Celeron processor, there may
be some issues with processor power control (cstates) that can result in a
lockup. This is a processor bug that affects "Bay Trail" CPUs, including
several Atom processors:
https://ark.intel.com/content/www/us/en/ark/products/codename/55844/products-formerly-bay-trail.html
. I ran into this on a J1900 Celeron that I use to control my 3D printer.

There are a couple of workarounds:
- Disable all cstates >1 with the kernel command line option
"intel_idle.max_cstate=1". This will mean that the processor will not be
able to microsleep to save power.
- Disable cstate 6 (the one that causes the problem) and enable cstate 7
with a shell script like the following:

#!/bin/sh

#title:       c6off+c7on.sh
#description: Disables all C6 and enables all C7 core states for Baytrail
CPUs
#author:      Wolfgang Reimer <linuxball (at) gmail.com>
#date:        2016014
#version:     1.0
#usage:       sudo <path>/c6off+c7on.sh
#notes:       Intended as test script to verify whether erratum VLP52 (see
#             [1]) is the root cause for kernel bug 109051 (see [2]). In
order
#             for this to work you must _NOT_ use boot parameter
#             intel_idle.max_cstate=<number>.
#
# [1]
http://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/pentium-n3520-j2850-celeron-n2920-n2820-n2815-n2806-j1850-j1750-spec-update.pdf
# [2] https://bugzilla.kernel.org/show_bug.cgi?id=109051

# Disable ($1 == 1) or enable ($1 == 0) core state, if not yet done.
disable() {
        local action
        read disabled <disable
        test "$disabled" = $1 && return
        echo $1 >disable || return
        action=ENABLED; test "$1" = 0 || action=DISABLED
        printf "%-8s state %7s for %s.\n" $action "$name" $cpu
}

# Iterate through each core state and for Baytrail (BYT) disable all C6
# and enable all C7 states.
cd /sys/devices/system/cpu
for cpu in cpu[0-9]*; do
        for dir in $cpu/cpuidle/state*; do
                cd "$dir"
                read name <name
                case $name in
                        C6*) disable 1;;
                        C7*) disable 0;;
                esac
                cd ../../..
        done
done

I have been using the above script successfully for over a year.

-- 
Manuel A. McLure WW1FA <manuel@mclure.org> <http://www.mclure.org>
...for in Ulthar, according to an ancient and significant law,
no man may kill a cat.                       -- H.P. Lovecraft

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