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

From: Guenter Roeck
Date: Tue Sep 01 2015 - 12:07:06 EST

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.


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