[dpdk-dev] librte_power w/ intel_pstate cpufreq governor

[longtb5 at viettel.com.vn]

Hi Dave,

Unfortunately I do not have access to our server BIOS settings. The power management task for our appliance is also on pending. I'm expecting to return to this task in April. Maybe we can still work out a patch before 18.05 (not sure about DPDK roadmap).

Regards,
-BL 

> -----Original Message-----
> From: david.hunt at intel.com [mailto:david.hunt at intel.com]
> Sent: Monday, March 5, 2018 6:26 PM
> To: longtb5 at viettel.com.vn; dev at dpdk.org
> Subject: Re: [dpdk-dev] librte_power w/ intel_pstate cpufreq governor
> 
> 
> Hi BL,
> 
> 
> On 5/3/2018 10:48 AM, longtb5 at viettel.com.vn
> <mailto:longtb5 at 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.hunt at intel.com <mailto:david.hunt at intel.com>
> [mailto:david.hunt at intel.com]
> 		Sent: Monday, March 5, 2018 5:16 PM
> 		To: longtb5 at viettel.com.vn <mailto:longtb5 at viettel.com.vn>
> ; dev at dpdk.org <mailto:dev at 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, longtb5 at viettel.com.vn
> <mailto:longtb5 at viettel.com.vn>  wrote:
> 
> 			Forgot to link the original thread.
> 
> 			http://dpdk.org/ml/archives/dev/2016-
> January/030930.html
> 
> 			-BL
> 
> 
> 				-----Original Message-----
> 				From: longtb5 at viettel.com.vn
> <mailto:longtb5 at viettel.com.vn>  [mailto:longtb5 at viettel.com.vn]
> 				Sent: Friday, March 2, 2018 2:19 PM
> 				To: dev at dpdk.org <mailto:dev at dpdk.org>
> 				Cc: david.hunt at intel.com
> <mailto:david.hunt at intel.com> ; mhall at mhcomputing.net
> <mailto:mhall at mhcomputing.net> ;
> 				helin.zhang at intel.com
> <mailto:helin.zhang at intel.com> ; longtb5 at viettel.com.vn
> <mailto:longtb5 at 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.
> 
> 
> 
>