Hi BL,
On 5/3/2018 10:48 AM, long...@viettel.com.vn wrote:
Hi Dave,
Actually in my test lab which is a HP box running CentOS 7 on kernel version
3.10.0-693.5.2.el7.x86_64, the default cpufreq driver is pcc_cpufreq. So I guess
disabling intel_pstate wouldn't help in my case.
# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver
pcc-cpufreq
# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
conservative userspace powersave ondemand performance
According to kernel doc, pcc_cpufreq also doesn't export
scaling_availabe_frequencies
in sysfs.
From kernel doc:
"scaling_available_frequencies is not created in /sys. No intermediate
frequencies need to be listed because the BIOS will try to achieve any
frequency, within limits, requested by the governor. A frequency does not have
to be strictly associated with a P-state."
The lack of scaling_availabe_frequencies makes power_acpi_cpufreq_init()
complains, similar to the problem with intel_pstate as in the other thread.
I have tried (though with not much effort) to force the kernel
to use acpi-cpufreq instead but without success.
Luckily, as quoted above pcc_cpufreq supports setting of arbitrary frequency,
so a simple workaround for now is to fake a scaling_available_frequencies file
in another directory, then edit the code in librte_power to use that file
instead.
Regards,
-BL
-----Original Message-----
From: david.h...@intel.com [mailto:david.h...@intel.com]
Sent: Monday, March 5, 2018 5:16 PM
To: long...@viettel.com.vn; dev@dpdk.org
Subject: Re: [dpdk-dev] librte_power w/ intel_pstate cpufreq governor
Hi BL,
I have always used "intel_pstate=disable" in my kernel parameters at boot so
as to disable the intel_pstate driver, and force the kernel to use the acpi-
cpufreq driver:
# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver
acpi-cpufreq
This then gives me the following options for the governor:
['conservative', 'ondemand', 'userspace', 'powersave', 'performance',
'schedutil']
Because DPDK threads typically poll, they appear as 100% busy to the p_state
driver, so if you want to be able to change core frequency down (as in l3fwd-
power), you need to use the acpi-cpufreq driver.
I had a read through the docs just now, and this does not seem to be
mentioned, so I'll do up a patch to give some information on the correct
kernel parameters to use when using the power library.
Regards,
Dave.
On 2/3/2018 7:20 AM, long...@viettel.com.vn wrote:
Forgot to link the original thread.
http://dpdk.org/ml/archives/dev/2016-January/030930.html
-BL
-----Original Message-----
From: long...@viettel.com.vn [mailto:long...@viettel.com.vn]
Sent: Friday, March 2, 2018 2:19 PM
To: dev@dpdk.org
Cc: david.h...@intel.com; mh...@mhcomputing.net;
helin.zh...@intel.com; long...@viettel.com.vn
Subject: librte_power w/ intel_pstate cpufreq governor
Hi everybody,
I know this thread was from over 2 years ago but I ran into the same
problem
with l3fwd-power today.
Any updates on this?
-BL
Good to hear you found a workaround.
So the issue really is "Getting the Power Library working with the
ppc-cpufreq kernel driver" :)
From wiki.archlinux.org:
ppc-cpufreq: his driver supports Processor Clocking Control interface by
Hewlett-Packard and Microsoft Corporation which is useful on some
ProLiant servers.
In the following doc:
https://www.kernel.org/doc/Documentation/cpu-freq/pcc-cpufreq.txt
it mentions - "When PCC mode is enabled, the platform will not expose
processor performance or throttle states (_PSS, _TSS and related ACPI
objects) to OSPM. Therefore,the native P-state driver (such as
acpi-cpufreq for Intel, powernow-k8 forAMD) will not load".
Is there a way to disable PPC mode in the BIOS on that server? From that
wording, it seems to imply imply that there is a way to disable PPC
(seeing that it can be enabled).
If you can't disbale PPC, I would suggest that a patch may be needed to
allow the power library detect if it's using acpi or ppc, and obtain a
list of cpu frequencies accordingly. However, I don't have any HP
servers available to me, so I'm currently unable to research a method of
getting a list of valid cpu frequencies on a machine using the ppc driver.
If you come up with a snippet of code for listing available frequencies
on that server, let me know and we can look at adding that into the
power library. :)
Regards,
Dave.
