Re: [PATCH 09/15] x86, amd: add accessor for number of cores per compute unit

Guenter Roeck
2015-09-01T16:07:01Z

On 09/01/2015 08:56 AM, Borislav Petkov wrote:
> On Mon, Aug 31, 2015 at 02:24:08PM -0700, Guenter Roeck wrote:
>> That is a matter of driver implementation. Very commonly hwmon drivers
>> implement value caching, where data from the device is only read at
>> minimum intervals, and the cached values are reported if the information
>> is polled too rapidly.
>
> I don't see how we can use cached values in that case as they'd be
> basically a lie as to how much power the CU/processor has consumed. I
> guess it would be fairer to the user to warn instead and not issue any
> values or to simply delay the read to a min timeout...
>

This is all a matter of ABI description. I personally don't see the
harm in caching values for up to <n> milliseconds and documenting that
readings may reflect power consumption from <n> milliseconds ago.
However, I don't mind any other solution either if that is considered
unacceptable, as long as that solution doesn't break the ABI.

Guenter