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12th gen Intel cpu's

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loaded:
This feature is also available in the program called Process Explorer;
The desired application can be run on the desired kernel.
If they have been able to do this, it can be done in Lazarusta.

PascalDragon:

--- Quote from: 440bx on December 02, 2021, 09:17:44 am ---
--- Quote from: PascalDragon on December 02, 2021, 08:59:25 am ---As both kind of cores have the same feature set there is nothing the compiler needs to do.

--- End quote ---
From what I've read, the efficiency cores are missing some instructions such as AVX512.

--- End quote ---

AVX512 is disabled by default. The efficiency cores need to be disabled so that AVX512 can be enabled for the power cores. See here. This is precisely for the reason that the operating system (and the CPU) can't know whether the program uses AVX512 instructions and thus might migrate a thread of such a program from a power core to an efficiency core (or start it there) and then there'd be an illegal instruction exception. (*) The point is that user applications should be able to run unmodified and thus great care is taken that the feature sets of both kind of cores match (there was a BIG.little ARM variant in the past where the cache line sizes of the two kinds of cores didn't match and that lead to all kinds of funny problems).

(*) Yes, in theory the OS could examine the instruction and reschedule the thread on a power core if the instruction is supported there, but that's apparently not done.

speter:
Thanks everyone. A very interesting discussion. :)

cheers
S.

Leledumbo:
AFAIK, there's no userland API to tell the OS which core the app should run on anyway. So, OS' CPU scheduler is what you can rely on.

marcov:

--- Quote from: Leledumbo on December 07, 2021, 09:30:21 am ---AFAIK, there's no userland API to tell the OS which core the app should run on anyway. So, OS' CPU scheduler is what you can rely on.

--- End quote ---

The term is called "Processor affinity", and it exists both for *nix (sched_setaffinity or so?) and Windows (https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-setprocessaffinitymask)

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