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Old 07-19-2011, 12:14 PM
Petr Sabata
 
Default Heads up: cpuspeed removed from f16+

To avoid some confusion:

I removed cpuspeed from Rawhide about 10 days ago. It no longer serves any
purpose in Fedora and has been effectively replaced by kernel cpufreq stack.

All cpufreq modules should now be built-in, with ondemand being the default
governor in Fedora.

In case you would to use a different governor and/or specific frequency, try the
new cpupower.service (provieded by cpupowerutils). Most people shouldn't need
this, though.

See https://bugzilla.redhat.com/show_bug.cgi?id=713572 for more info.

Regards,
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Old 07-19-2011, 01:04 PM
Rahul Sundaram
 
Default Heads up: cpuspeed removed from f16+

On 07/19/2011 05:44 PM, Petr Sabata wrote:
> To avoid some confusion:
>
> I removed cpuspeed from Rawhide about 10 days ago. It no longer serves any
> purpose in Fedora and has been effectively replaced by kernel cpufreq stack.
>
> All cpufreq modules should now be built-in, with ondemand being the default
> governor in Fedora.

Would you add a note to

https://fedoraproject.org/wiki/Fedora_16_Alpha_release_notes

Rahul
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Old 07-19-2011, 01:20 PM
Petr Sabata
 
Default Heads up: cpuspeed removed from f16+

On Tue, Jul 19, 2011 at 06:34:36PM +0530, Rahul Sundaram wrote:
> On 07/19/2011 05:44 PM, Petr Sabata wrote:
> > To avoid some confusion:
> >
> > I removed cpuspeed from Rawhide about 10 days ago. It no longer serves any
> > purpose in Fedora and has been effectively replaced by kernel cpufreq stack.
> >
> > All cpufreq modules should now be built-in, with ondemand being the default
> > governor in Fedora.
>
> Would you add a note to
>
> https://fedoraproject.org/wiki/Fedora_16_Alpha_release_notes

Done.

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Old 07-19-2011, 01:35 PM
"Nicolas Mailhot"
 
Default Heads up: cpuspeed removed from f16+

Le Mar 19 juillet 2011 14:14, Petr Sabata a crit :

> In case you would to use a different governor and/or specific frequency, try
> the
> new cpupower.service (provieded by cpupowerutils). Most people shouldn't need
> this, though.

Will cpupowerutils obsolete cpufreq so old deployments of cpufreq can be
garbage-collected ? (yes most people will not need it, but is it not better to
have something current installed rather than cpufreq living on forever? I'm
thinking of eternal yum-updated systems here)

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Old 07-19-2011, 01:41 PM
Petr Sabata
 
Default Heads up: cpuspeed removed from f16+

On Tue, Jul 19, 2011 at 03:35:36PM +0200, Nicolas Mailhot wrote:
>
> Le Mar 19 juillet 2011 14:14, Petr Sabata a crit :
>
> > In case you would to use a different governor and/or specific frequency, try
> > the
> > new cpupower.service (provieded by cpupowerutils). Most people shouldn't need
> > this, though.
>
> Will cpupowerutils obsolete cpufreq so old deployments of cpufreq can be
> garbage-collected ? (yes most people will not need it, but is it not better to
> have something current installed rather than cpufreq living on forever? I'm
> thinking of eternal yum-updated systems here)

It's not the case at the moment.

I was thinking about it before and didn't really like it. But it's
just a matter of taste and having yet another Obsoletes/Provides pair in
cpupowerutils.spec won't hurt.

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Old 07-19-2011, 02:59 PM
Jaroslav Skarvada
 
Default Heads up: cpuspeed removed from f16+

----- Original Message -----
> To avoid some confusion:
>
> I removed cpuspeed from Rawhide about 10 days ago. It no longer serves
> any
> purpose in Fedora and has been effectively replaced by kernel cpufreq
> stack.
>
> All cpufreq modules should now be built-in, with ondemand being the
> default
> governor in Fedora.
>
> In case you would to use a different governor and/or specific
> frequency, try the
> new cpupower.service (provieded by cpupowerutils). Most people
> shouldn't need
> this, though.
>
> See https://bugzilla.redhat.com/show_bug.cgi?id=713572 for more info.
>
> Regards,
> --
> # Petr Sabata
>
> --
> devel mailing list
> devel@lists.fedoraproject.org
> https://admin.fedoraproject.org/mailman/listinfo/devel

Sad that the daemon gone. It was able to dynamically switch speed
(and save power) on systems that have CPUs with high transition
latency (e.g. old P4, some Atoms, etc.). On such systems the
ondemand governor cannot be used and if you want to save power
you need to change the freq from userspace (of course, not too
frequently). It was not the best solution, but it worked, e.g.:
http://bugzilla.redhat.com/show_bug.cgi?id=697273
Is there any replacement?

regards

Jaroslav
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Old 07-19-2011, 03:06 PM
Petr Sabata
 
Default Heads up: cpuspeed removed from f16+

On Tue, Jul 19, 2011 at 10:59:30AM -0400, Jaroslav Skarvada wrote:
> ----- Original Message -----
> > To avoid some confusion:
> >
> > I removed cpuspeed from Rawhide about 10 days ago. It no longer serves
> > any
> > purpose in Fedora and has been effectively replaced by kernel cpufreq
> > stack.
> >
> > All cpufreq modules should now be built-in, with ondemand being the
> > default
> > governor in Fedora.
> >
> > In case you would to use a different governor and/or specific
> > frequency, try the
> > new cpupower.service (provieded by cpupowerutils). Most people
> > shouldn't need
> > this, though.
> >
> > See https://bugzilla.redhat.com/show_bug.cgi?id=713572 for more info.
> >
> > Regards,
> > --
> > # Petr Sabata
> >
> > --
> > devel mailing list
> > devel@lists.fedoraproject.org
> > https://admin.fedoraproject.org/mailman/listinfo/devel
>
> Sad that the daemon gone. It was able to dynamically switch speed
> (and save power) on systems that have CPUs with high transition
> latency (e.g. old P4, some Atoms, etc.). On such systems the
> ondemand governor cannot be used and if you want to save power
> you need to change the freq from userspace (of course, not too
> frequently). It was not the best solution, but it worked, e.g.:
> http://bugzilla.redhat.com/show_bug.cgi?id=697273
> Is there any replacement?

In my opinion, the proper way to deal with this is to fix kernel drivers
and/or governors, not some special userspace hacks.
https://bugzilla.redhat.com/show_bug.cgi?id=713572#c9

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Old 07-19-2011, 03:07 PM
Eric Sandeen
 
Default Heads up: cpuspeed removed from f16+

On 07/19/2011 09:59 AM, Jaroslav Skarvada wrote:
> ----- Original Message -----
>> To avoid some confusion:
>>
>> I removed cpuspeed from Rawhide about 10 days ago. It no longer serves
>> any
>> purpose in Fedora and has been effectively replaced by kernel cpufreq
>> stack.
>>
>> All cpufreq modules should now be built-in, with ondemand being the
>> default
>> governor in Fedora.
>>
>> In case you would to use a different governor and/or specific
>> frequency, try the
>> new cpupower.service (provieded by cpupowerutils). Most people
>> shouldn't need
>> this, though.
>>
>> See https://bugzilla.redhat.com/show_bug.cgi?id=713572 for more info.
>>
>> Regards,
>> --
>> # Petr Sabata
>>
>> --
>> devel mailing list
>> devel@lists.fedoraproject.org
>> https://admin.fedoraproject.org/mailman/listinfo/devel
>
> Sad that the daemon gone. It was able to dynamically switch speed
> (and save power) on systems that have CPUs with high transition
> latency (e.g. old P4, some Atoms, etc.). On such systems the

Actually, no...

http://codemonkey.org.uk/2009/01/18/forthcoming-p4clockmod/

> So the 1.00GHz ‘frequency’ is actually “run at 2GHz, but only do work 50% of the time”.
>
> On the surface, this sounds like a good idea. The other 50%, the CPU is idle, so you’re saving power, right?
> Not so much. In fact, you could be burning more power. The reason for this is that when the processor is sitting there doing nothing, it isn’t lower frequency, and more importantly, it very likely isn’t entering C states. So you’re burning the same amount of power, but now you’re only doing work for 50% of the time. As a result of this, your workload takes twice as long to complete.

I've measured it, and Dave is right. You might get something saying
"1.0Ghz" but you're not saving anything at all.

-Eric
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Old 07-19-2011, 03:21 PM
Jaroslav Skarvada
 
Default Heads up: cpuspeed removed from f16+

----- Original Message -----
> On 07/19/2011 09:59 AM, Jaroslav Skarvada wrote:
> > ----- Original Message -----
> >> To avoid some confusion:
> >>
> >> I removed cpuspeed from Rawhide about 10 days ago. It no longer
> >> serves
> >> any
> >> purpose in Fedora and has been effectively replaced by kernel
> >> cpufreq
> >> stack.
> >>
> >> All cpufreq modules should now be built-in, with ondemand being the
> >> default
> >> governor in Fedora.
> >>
> >> In case you would to use a different governor and/or specific
> >> frequency, try the
> >> new cpupower.service (provieded by cpupowerutils). Most people
> >> shouldn't need
> >> this, though.
> >>
> >> See https://bugzilla.redhat.com/show_bug.cgi?id=713572 for more
> >> info.
> >>
> >> Regards,
> >> --
> >> # Petr Sabata
> >>
> >> --
> >> devel mailing list
> >> devel@lists.fedoraproject.org
> >> https://admin.fedoraproject.org/mailman/listinfo/devel
> >
> > Sad that the daemon gone. It was able to dynamically switch speed
> > (and save power) on systems that have CPUs with high transition
> > latency (e.g. old P4, some Atoms, etc.). On such systems the
>
> Actually, no...
>
> http://codemonkey.org.uk/2009/01/18/forthcoming-p4clockmod/
>
> > So the 1.00GHz ‘frequency’ is actually “run at 2GHz, but only do
> > work 50% of the time”.
> >
> > On the surface, this sounds like a good idea. The other 50%, the CPU
> > is idle, so you’re saving power, right?
> > Not so much. In fact, you could be burning more power. The reason
> > for this is that when the processor is sitting there doing nothing,
> > it isn’t lower frequency, and more importantly, it very likely isn’t
> > entering C states. So you’re burning the same amount of power, but
> > now you’re only doing work for 50% of the time. As a result of this,
> > your workload takes twice as long to complete.
>
> I've measured it, and Dave is right. You might get something saying
> "1.0Ghz" but you're not saving anything at all.
>
> -Eric

It is heating less, but you are not saving power? Sorry, but I cannot
understand. The more energy consumed for the same computational
load is another story

Jaroslav
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Old 07-19-2011, 03:23 PM
Przemek Klosowski
 
Default Heads up: cpuspeed removed from f16+

On 07/19/2011 11:07 AM, Eric Sandeen wrote:
> On 07/19/2011 09:59 AM, Jaroslav Skarvada wrote:

>> Sad that the daemon gone. It was able to dynamically switch speed
>> (and save power) on systems that have CPUs with high transition
>> latency (e.g. old P4, some Atoms, etc.). On such systems the
>
> Actually, no...
>
> http://codemonkey.org.uk/2009/01/18/forthcoming-p4clockmod/
>
>> So the 1.00GHz ‘frequency’ is actually “run at 2GHz, but only do work 50% of the time”.
>>
>> On the surface, this sounds like a good idea. The other 50%, the CPU is idle, so you’re saving power, right?
>> Not so much. In fact, you could be burning more power. The reason for this is that when the processor is sitting there doing nothing, it isn’t lower frequency, and more importantly, it very likely isn’t entering C states. So you’re burning the same amount of power, but now you’re only doing work for 50% of the time. As a result of this, your workload takes twice as long to complete.
>
> I've measured it, and Dave is right. You might get something saying
> "1.0Ghz" but you're not saving anything at all.

There are second-order effects---the processor probably doesn't use
significantly less power but the graphic card and chipset do, for some
overall system effects---people quoted numbers like 20% battery savings
for 50% slowdown (if p4_clockmod really stopped the CPU 50% of the time,
it'd double the battery life, so this really is a very inefficient and
crude method).
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