Re: [PATCH v2 1/2] cpufreq/ondemand: Introduce op to customize mapping of load to frequency

From: Andreas Herrmann
Date: Tue Oct 11 2016 - 02:30:32 EST


On Wed, Oct 05, 2016 at 09:31:18AM +0530, Viresh Kumar wrote:
> On 23-09-16, 19:02, Andreas Herrmann wrote:
> > Introduce op for ondemand governor that is used to map load to
> > frequency. It allows a cpufreq driver to provide a specific mapping
> > function if the generic function is not optimal for the driver.
> >
> > Performance results (kernel compile with different number of jobs)
> > based on 4.8.0-rc7 (with and w/o my patches on top) from
> > an HP ProLiant DL580 Gen8 system using pcc-cpufreq:
> > - Intel(R) Xeon(R) CPU E7-4890 v2 @ 2.80GHz
> > - 60 CPUs, 128GB RAM
> >
> > vanilla generic_map_load_to_freq function
> > # of jobs user sys elapsed % CPU user sys elapsed % CPU
> > 2 445.44 110.51 272.99 203.00 445.56 111.22 273.35 203.00
> > 4 444.41 126.20 142.81 399.00 445.61 126.10 143.12 399.00
> > 8 483.04 150.58 82.19 770.40 483.51 150.84 82.17 771.40
> > 16 626.81 185.01 55.00 1475.40 628.01 185.54 55.02 1477.80
> > 32 816.72 204.39 37.26 2740.00 818.58 205.51 37.02 2765.40
> > 64 406.59 51.12 14.04 3257.80 406.22 51.84 13.84 3308.80
> > 120 413.00 48.39 14.36 3211.20 413.61 49.06 14.54 3181.00
> >
> > Similar tests on another system using acpi_cpufreq didn't show
> > significant performance differences between these two kernel versions.
> >
> > Link: https://marc.info/?i=20160819121814.GA17296%40suselix.suse.de
> > Signed-off-by: Andreas Herrmann <aherrmann@xxxxxxxx>
> > ---
> > drivers/cpufreq/cpufreq_governor.h | 5 +++++
> > drivers/cpufreq/cpufreq_ondemand.c | 35 ++++++++++++++++++++++++++++++-----
> > 2 files changed, 35 insertions(+), 5 deletions(-)
>
> NAK.
>
> If we are absolutely required to hack it in some way, then I would
> prefer your first patchset as the noise was limited to only your
> driver.
>
> We aren't going to provide such operations from the governors, sorry.

Yep, understandable.


Andreas