Re: [PATCH v3 linux-next] cpufreq: ondemand: Calculate gradient ofCPU load to early increase frequency

[Viresh Kumar]

Hi Stratos,

On 4 April 2013 05:00, Stratos Karafotis <stratosk@xxxxxxxxxxxx> wrote:
> I tried to do some measurements simulating a CPU load with a loop that simply counts
> an integer. The first test simulates a CPU load that lasts 2 x sampling_rate = ~ 20000us.
> The second ~40000us and the third ~60000us.
> There are 5 runs in each test. In each run the benchmark program counts 20 times with
> early_demand off and 20 times with early_demand on and takes the average times.
>
> I run the benchmark program on 3.9-rc5 + early_demand patch. My CPU is the i7-3770 @ 3.40 GHz
>
> Please find below the results, and the benchmark code attached.
> Please note, that the idea of this patch is to push the CPU to max frequency few sampling
> periods (1 in most cases) earlier for a more responsive system.

Yes, your results show some improvements. BUT if performance is the only thing
we were looking for, then we will never use ondemand governor but performance
governor.

I suspect this little increase in performance must have increased power numbers
too (significantly). So, if you can get numbers in the form of power/performance
with and without your patch, it will be great.

--
viresh
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/