Re: [PATCH 3/6 v4] cpufreq: tolerate inexact values when collecting stats

Mark Langsdorf
2012-11-12T16:35:36Z

On 11/11/2012 10:38 AM, Borislav Petkov wrote:
> On Wed, Nov 07, 2012 at 12:32:43PM -0600, Mark Langsdorf wrote:
>> When collecting stats, if a frequency doesn't match the table, go through
>> the table again with both the search frequency and table values shifted
>> left by 10 bits.
>
> Why would that second pass succeed?

It's effectively a divide by 1024 and minimizes any jitter in the
measured frequency value.

> And why is this in generic code (I'm assuming this is a Calxeda-specific
> case)?

The function is buried pretty deep in the cpufreq_stat code. It didn't
seem appropriate to make it a function pointer as part of struct
cpufreq_driver.

--Mark Langsdorf
Calxeda, Inc.