RE: [PATCH] cacheinfo: Introduce cache id

[Yu, Fenghua]

> From: Borislav Petkov [mailto:bp@xxxxxxx]
> Sent: Friday, July 01, 2016 11:29 AM
> To: Luck, Tony <tony.luck@xxxxxxxxx>
> Cc: Yu, Fenghua <fenghua.yu@xxxxxxxxx>; Thomas Gleixner
> <tglx@xxxxxxxxxxxxx>; Ingo Molnar <mingo@xxxxxxx>; Anvin, H Peter
> <h.peter.anvin@xxxxxxxxx>; Peter Zijlstra <peterz@xxxxxxxxxxxxx>;
> Stephane Eranian <eranian@xxxxxxxxxx>; Shankar, Ravi V
> <ravi.v.shankar@xxxxxxxxx>; Vikas Shivappa
> <vikas.shivappa@xxxxxxxxxxxxxxx>; linux-kernel <linux-
> kernel@xxxxxxxxxxxxxxx>; x86 <x86@xxxxxxxxxx>
> Subject: Re: [PATCH] cacheinfo: Introduce cache id
> 
> On Fri, Jul 01, 2016 at 11:00:35AM -0700, Luck, Tony wrote:
> > For CAT we only need the IDs to be unique at each level. Our tentative
> > syntax for the schema file for CAT looks like this (for a theoretical
> > system supporting CAT in both L2 and L3 with two L3 caches and eight
> > L2 caches)
> >
> > L3:id0=fff;id1=ff0
> > L2:id0=3;id1=c;id2=30;id3=c0;id4=3;id5=c;id6=30;id7=c0
> 
> So wouldn't it be straightforward and natural to do the following
> nomenclature (which basically suggests itself):
> 
> ID<level>.<num>

We has prefix "L3" or "L2" in the syntax, id is for that level in each line.b

> 
> ?
> 
> So that the ID hierarchy above is:
> 
> ID3.0 ID3.1
> ID2.0 ID2.1 ID2.2 ID2.3 ... ID2.7
> 
> I don't know if that's useful though.
> 
> I mean, we have that info in the path anyway:
> 
> /sys/devices/system/cpu/cpu0/cache/index3/id = 0xfff ...
> 
> and so on.
> 
> Whatever you do, as long as the nomenclature is documented somewhere,
> say Documentation/x86/topology.txt, for example, we should be fine.
> 
> --
> Regards/Gruss,
>     Boris.
> 
> SUSE Linux GmbH, GF: Felix ImendÃrffer, Jane Smithard, Graham Norton,
> HRB 21284 (AG NÃrnberg)
> --