Messages in this thread | | | Date | Mon, 23 Jan 2017 10:57:26 -0800 (PST) | From | Shivappa Vikas <> | Subject | Re: [PATCH 1/8] Documentation, x86: Documentation for Intel Mem b/w allocation user interface |
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On Wed, 18 Jan 2017, Thomas Gleixner wrote:
> On Tue, 17 Jan 2017, Shivappa Vikas wrote: >> On Mon, 16 Jan 2017, Thomas Gleixner wrote: >>> This interface is really crap. The natural way to express it is: >>> >>> Requested Bandwidth = X % >> >> I wanted to do it this way which did seem more intuitive but the issue is with >> the non-linear scale which the hardware does not guarantee a particular >> percentage for a particular value. Or we don't know the curve for delay value >> vs. actual b/w throttled. >> >> ex: in non linear scale , the granularity is 2^n. >> Max : 512 >> >> Say a value of 256 is not guaranteed to have 50% or even follow a curve where >> we can calculate the corresponding percentage. > > The question is whether this non linear scale thing is just a first > implementation attempt and any sane hardware in the future will use the > percentage value (which is an approximation as well). > > If that non-linear scale is not going to be prevalent, then we really can > live with the fallout of a particular CPU type. > > If it's going to stay, then Intel should be able to provide simple tables > which give us the required information for a particular CPU model.
By sample table - does this mean we can map a throttle value in non-linear scale to its percentage ?
Thanks, Vikas
> > Thanks, > > tglx >
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