[lkml]   [2018]   [Mar]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH V2 0/7] CPU cooling device new strategies
On Thu, Mar 08, 2018 at 12:03:52PM +0000, Daniel Thompson wrote:
> On Wed, Mar 07, 2018 at 07:57:17PM +0100, Daniel Lezcano wrote:
> > >> The preliminary benchmarks show the following changes:
> > >>
> > >> On the hikey6220, dhrystone shows a throughtput increase of 40% for an
> > >> increase of the latency of 16% while sysbench shows a latency increase
> > >> of 5%.
> > >
> > > I don't follow these numbers. Throughput increase while injecting idle?
> > > compared to what? percentages of what? Please be more specific to better
> > > describer your work..
> >
> > The dhrystone throughput is based on the virtual timer, when we are
> > running, it is at max opp, so the throughput increases. But regarding
> > the real time, it takes obviously more time to achieve as we are
> > artificially inserting idle cycles. With the cpufreq governor, we run at
> > a lower opp, so the throughput is less for dhrystone but it takes less
> > time to achieve.
> >
> > Percentages are comparing cpufreq vs cpuidle cooling devices. I will
> > take care of presenting the results in a more clear way in the next version.
> I think we should also note that the current hikey settings for cpufreq
> are very badly tuned for this platform. It has a single temp threshold
> and it jumps from max freq to min freq.
> IIRC Leo's work on Hikey thermals correctly it would be much better if
> it used the power-allocator thermal governor or if if copied some of
> the Samsung 32-bit platform by configuring the step governor with a
> graduated with a slightly lower threshold that moves two stops back in
> the OPP table (which is still fairly high clock speed... but it
> thermally sustainable).

I think Daniel L. is working on this patch set with 'power-allocator'
governor, and the parameters 'sustainable-power = <3326>' and
'dynamic-power-coefficient = <311>' are profiling value on Hikey
platform. Now we only consider dynamic power and skip static leakage
for 'power-allocator' governor. And all these parameters are merged
into Linux mainline kernel.

Daniel L. could correct me if I misunderstand the testing conditions.

Leo Yan

 \ /
  Last update: 2018-03-26 16:32    [W:0.122 / U:0.472 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site