Messages in this thread |  | | From | Thomas Gleixner <> | Subject | Re: [PATCH 0/3] x86: Add initial support to discover Intel hybrid CPUs | Date | Sat, 03 Oct 2020 12:46:29 +0200 |
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On Fri, Oct 02 2020 at 19:17, Tony Luck wrote:
> On Sat, Oct 03, 2020 at 03:39:29AM +0200, Thomas Gleixner wrote: >> On Fri, Oct 02 2020 at 13:19, Ricardo Neri wrote: >> > Add support to discover and enumerate CPUs in Intel hybrid parts. A hybrid >> > part has CPUs with more than one type of micro-architecture. Thus, certain >> > features may only be present in a specific CPU type. >> > >> > It is useful to know the type of CPUs present in a system. For instance, >> > perf may need to handle CPUs differently depending on the type of micro- >> > architecture. Decoding machine check error logs may need the additional >> > micro-architecture type information, so include that in the log. >> >> 'It is useful' as justification just makes me barf. > > This isn't "hetero" ... all of the cores are architecturally the same.
The above clearly says:
>> > A hybrid part has CPUs with more than one type of micro-architecture.
Can you folks talk to each other and chose non-ambigous wording in changelogs and cover letters?
> If CPUID says that some feature is supported, then it will be supported > on all of the cores.
That's a different story.
> There might be some model specific performance counter events that only > apply to some cores. Or a machine check error code that is logged in the > model specific MSCOD field of IA32_MCi_STATUS. But any and all code can run > on any core.
Ok. The perf side should be doable, IIRC we already have something like that, but Peter should know better.
> Sure there will be some different power/performance tradeoffs on some > cores. But we already have that with some cores able to achieve higher > turbo frequencies than others.
Right, that's not a problem.
Thanks,
tglx
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