[PATCHSET] 0/3 Dynamic cpufreq governor and updates to ACPI P-state driver

[PATCHSET] 0/3 Dynamic cpufreq governor and updates to ACPI P-state driver

[Pallipadi, Venkatesh]

Hi,

Most of the latest CPUs (laptop CPUs in particular) have feature 
which enable very low latency P-state transitions 
(like Enhanced Speedstep Technology-EST). Using this feature, 
we can have a lightweight in kernel cpufreq governor, 
to vary CPU frequency depending on the CPU usage. The 
advantage being low power consumption and also cooler laptops.

Another related change is enhancing the current ACPI P-state 
driver to handle:
EST (and MSR based P-state transitions), make the driver SMP 
aware and introduce HT coordination in the driver (HT siblings 
share the same CPU frequency).

The patches that follow this mail addresses the above issues. 
They are against 2.6-test7 kernel. Many thanks to Dominik for 
his comments and suggestions.

The patches will work on all laptops with EST technology 
(Centrino) and also on any other system that supports low 
latency frequency change. 

Reviews/testing of patches are most welcome.

Thanks,
-Venkatesh


Patches are split as follows:

Patch 1/3: Changes to ACPI P-state driver, to handle MSR 
based transitions frequency transitions and make the driver 
SMP aware.

Patch 2/3: Introduce HT-synchronization in the ACPI P-state 
Driver, to take care of shared CPU frequency between HT siblings.

Patch 3/3: New dynamic cpufreq driver (called 
DemandBasedSwitch driver), which periodically monitors CPU 
usage and changes the CPU frequency based on the demand.

Re: [PATCHSET] 0/3 Dynamic cpufreq governor and updates to ACPI P-state driver

[Måns Rullgård]

"Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com> writes:

> Most of the latest CPUs (laptop CPUs in particular) have feature 
> which enable very low latency P-state transitions 
> (like Enhanced Speedstep Technology-EST). Using this feature, 
> we can have a lightweight in kernel cpufreq governor, 
> to vary CPU frequency depending on the CPU usage. The 
> advantage being low power consumption and also cooler laptops.

So, how does this work?  I'd like to be able to set minimum and
maximum clock frequencies to allow, and CPU utilization thresholds at
which to switch frequencies.  Is that possible, or is it work yet to
be done?  Adjustable polling interval would also be nice.

> The patches will work on all laptops with EST technology 
> (Centrino) and also on any other system that supports low 
> latency frequency change. 

Does Pentium 4 M work?

-- 
Måns Rullgård
mru@kth.se

Re: [PATCHSET] 0/3 Dynamic cpufreq governor and updates to ACPI P-state driver

[Alexander Bokovoy]

On Tue, Oct 21, 2003 at 12:57:15PM +0200, M?ns Rullg?rd wrote:
> "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com> writes:
> 
> > Most of the latest CPUs (laptop CPUs in particular) have feature 
> > which enable very low latency P-state transitions 
> > (like Enhanced Speedstep Technology-EST). Using this feature, 
> > we can have a lightweight in kernel cpufreq governor, 
> > to vary CPU frequency depending on the CPU usage. The 
> > advantage being low power consumption and also cooler laptops.
> 
> So, I took this thing for a spin, but it didn't work at all.  I loaded
> the module, and did "echo demandbased > /sys/.../scaling_governor".
> This echo never returned, and the keyboard locked up.  After a little
> while, the fan started running at full speed.  I managed to cut and
> paste into an xterm and start top, which showed nothing unusual.  I
> could shut down and reboot normally.
I applied these patches to stock 2.6.0-test8 and selected 'demandbased' as
default governor. In result, everything worked from the very beginning, my
Centrino-based system went to 600MHz and was upping when load was going
higher during compilation or disk access but went down when load was
lowering. So it works well for me.
-- 
/ Alexander Bokovoy
Samba Team                      http://www.samba.org/
ALT Linux Team                  http://www.altlinux.org/
Midgard Project Ry              http://www.midgard-project.org/

Re: [PATCHSET] 0/3 Dynamic cpufreq governor and updates to ACPI P-state driver

[Alexander Bokovoy]

On Tue, Oct 21, 2003 at 10:39:16PM +0200, M?ns Rullg?rd wrote:
> Alexander Bokovoy <ab@altlinux.org> writes:
> 
> >> > Most of the latest CPUs (laptop CPUs in particular) have feature 
> >> > which enable very low latency P-state transitions 
> >> > (like Enhanced Speedstep Technology-EST). Using this feature, 
> >> > we can have a lightweight in kernel cpufreq governor, 
> >> > to vary CPU frequency depending on the CPU usage. The 
> >> > advantage being low power consumption and also cooler laptops.
> >> 
> >> So, I took this thing for a spin, but it didn't work at all.  I loaded
> >> the module, and did "echo demandbased > /sys/.../scaling_governor".
> >> This echo never returned, and the keyboard locked up.  After a little
> >> while, the fan started running at full speed.  I managed to cut and
> >> paste into an xterm and start top, which showed nothing unusual.  I
> >> could shut down and reboot normally.
> > I applied these patches to stock 2.6.0-test8 and selected 'demandbased' as
> > default governor. In result, everything worked from the very beginning, my
> > Centrino-based system went to 600MHz and was upping when load was going
> > higher during compilation or disk access but went down when load was
> > lowering. So it works well for me.
> 
> What's your /proc/cpuinfo?  Mine says
> 
> processor	: 0
> vendor_id	: GenuineIntel
> cpu family	: 15
> model		: 2
> model name	: Mobile Intel(R) Pentium(R) 4 - M CPU 1.80GHz
> stepping	: 7
> cpu MHz		: 2069.912
> cache size	: 512 KB
> fdiv_bug	: no
> hlt_bug		: no
> f00f_bug	: no
> coma_bug	: no
> fpu		: yes
> fpu_exception	: yes
> cpuid level	: 2
> wp		: yes
> flags		: fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe cid
> bogomips	: 4087.80
As I said, it is Centrino-based, with 1.3GHz Pentium M:

processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 9
model name	: Intel(R) Pentium(R) M processor 1300MHz
stepping	: 5
cpu MHz		: 597.592
cache size	: 1024 KB
fdiv_bug	: no
hlt_bug		: no
f00f_bug	: no
coma_bug	: no
fpu		: yes
fpu_exception	: yes
cpuid level	: 2
wp		: yes
flags		: fpu vme de pse tsc msr mce cx8 apic sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 tm
bogomips	: 1192.75

Note the current CPU MHz sticking to ~600 -- it is cpufreq's result.

-- 
/ Alexander Bokovoy
Samba Team                      http://www.samba.org/
ALT Linux Team                  http://www.altlinux.org/
Midgard Project Ry              http://www.midgard-project.org/

Re: [PATCHSET] 0/3 Dynamic cpufreq governor and updates to ACPI P-state driver

[Alexander Bokovoy]

On Tue, Oct 21, 2003 at 11:37:16PM +0200, M?ns Rullg?rd wrote:
> Alexander Bokovoy <ab@altlinux.org> writes:
> 
> >> What's your /proc/cpuinfo?  Mine says
> >> 
> >> processor	: 0
> >> vendor_id	: GenuineIntel
> >> cpu family	: 15
> >> model	: 2
> >> model name	: Mobile Intel(R) Pentium(R) 4 - M CPU 1.80GHz
> >> stepping	: 7
> 
> > As I said, it is Centrino-based, with 1.3GHz Pentium M:
> >
> > processor	: 0
> > vendor_id	: GenuineIntel
> > cpu family	: 6
> > model		: 9
> > model name	: Intel(R) Pentium(R) M processor 1300MHz
> > stepping	: 5
> 
> So, mine won't work, or what?
If you can boot into 2.4.22 or .23pre with ACPI enabled and can see
/proc/acpi/processor/CPU0/performance, then your processor should be
supported by speedstep-ich or speedstep-piix4 modules (don't know which
one exactly).
-- 
/ Alexander Bokovoy
Samba Team                      http://www.samba.org/
ALT Linux Team                  http://www.altlinux.org/
Midgard Project Ry              http://www.midgard-project.org/

RE: [PATCHSET] 0/3 Dynamic cpufreq governor and updates to ACPI P-state driver

[Pallipadi, Venkatesh]

> -----Original Message-----
> From: linux-kernel-owner@vger.kernel.org 
> [mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Måns Rullgård
> 
> So, how does this work?  I'd like to be able to set minimum and
> maximum clock frequencies to allow, and CPU utilization thresholds at
> which to switch frequencies.  Is that possible, or is it work yet to
> be done?  Adjustable polling interval would also be nice.
> 

Yes. You can set the maximum and minimum allowed frequencies using 
the standard cpufreq interface. Something like:
echo 800000 >  /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq

However, other interfaces to tune this particular governor is not 
there yet. Other tunables that will be exported to user in future are 
Polling interval and CPU utilization thresholds.

> > The patches will work on all laptops with EST technology 
> > (Centrino) and also on any other system that supports low 
> > latency frequency change. 
> 
> Does Pentium 4 M work?

AFAIK, P4M does not support EST. You can double check with 
/proc/cpuinfo and look out for EST flag.


Thanks,
-Venkatesh

RE: [PATCHSET] 0/3 Dynamic cpufreq governor and updates to ACPI P-state driver

[Pallipadi, Venkatesh]

> -----Original Message-----
> From: linux-kernel-owner@vger.kernel.org 
> [mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of 
> Alexander Bokovoy
> Sent: Tuesday, October 21, 2003 2:11 PM
> To: M?ns Rullg?rd
> Cc: cpufreq@www.linux.org.uk; linux-kernel@vger.kernel.org
> Subject: Re: [PATCHSET] 0/3 Dynamic cpufreq governor and 
> updates to ACPI P-state driver
> 
> 
> On Tue, Oct 21, 2003 at 10:39:16PM +0200, M?ns Rullg?rd wrote:
> > Alexander Bokovoy <ab@altlinux.org> writes:
> > 
> > >> > Most of the latest CPUs (laptop CPUs in particular) 
> have feature 
> > >> > which enable very low latency P-state transitions 
> > >> > (like Enhanced Speedstep Technology-EST). Using this feature, 
> > >> > we can have a lightweight in kernel cpufreq governor, 
> > >> > to vary CPU frequency depending on the CPU usage. The 
> > >> > advantage being low power consumption and also cooler laptops.
> > >> 
> > >> So, I took this thing for a spin, but it didn't work at 
> all.  I loaded
> > >> the module, and did "echo demandbased > 
> /sys/.../scaling_governor".
> > >> This echo never returned, and the keyboard locked up.  
> After a little
> > >> while, the fan started running at full speed.  I managed 
> to cut and
> > >> paste into an xterm and start top, which showed nothing 
> unusual.  I
> > >> could shut down and reboot normally.
> > > I applied these patches to stock 2.6.0-test8 and selected 
> 'demandbased' as
> > > default governor. In result, everything worked from the 
> very beginning, my
> > > Centrino-based system went to 600MHz and was upping when 
> load was going
> > > higher during compilation or disk access but went down 
> when load was
> > > lowering. So it works well for me.
> > 
> > What's your /proc/cpuinfo?  Mine says
> > 
> > processor	: 0
> > vendor_id	: GenuineIntel
> > cpu family	: 15
> > model		: 2
> > model name	: Mobile Intel(R) Pentium(R) 4 - M CPU 1.80GHz


AFAIK, Pentium 4 M does not support EST (Frequency transitions with low
latency). 
But that doesn't explain why it is hanging though. Which speedstep
driver are you using?
P4-clockmod? Or acpi? Can you send the complete dmesg.


Thanks,
-Venkatesh