RFR: 8365633: Incorrect info is reported on hybrid CPU [v2]

[David Holmes]

On Thu, 21 Aug 2025 15:23:25 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> I removed number of threads information on hybrid CPU. @dholmes-ora Can you review?  
>> We can get following strings on hybrid CPU after this change:
>> 
>> 
>> CPU: total 14 (initial active 14)  family 6 model 181 stepping 0 microcode 0xffffffff, cx8, cmov, fxsr, ht, mmx, 3dnowpref, sse, sse2, sse3, ssse3, sse4.1, sse4.2, popcnt, lzcnt, tsc, tscinvbit, avx, avx2, aes, erms, clmul, bmi1, bmi2, adx, sha, fma, vzeroupper, clflush, clflushopt, clwb, hv, serialize, rdtscp, rdpid, fsrm, gfni, f16c, cet_ibt, cet_ss, hybrid
>> CPU Model and flags from /proc/cpuinfo:
>> model name      : Intel(R) Core(TM) Ultra 5 225U
>
> @YaSuenag  Is it possible to find from CPUID or OS calls the information about hybrid CPU configuration?
> 
> "( 2 P cores, 8 E cores, 2 LP cores)" in you case.  I would prefer if for hybrid CPU we print that info instead of "(7 cores per cpu, 2 threads per core) ".
> 
> It is important information when we debug issue on such CPUs.

@vnkozlov I'd like it if we could produce accurate information too but the OS doesn't supply it to us and doing it via CPUID is absurdly complicated. VMVersion is not setup to handle different kinds of cores.

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PR Comment: https://git.openjdk.org/jdk/pull/26808#issuecomment-3212532526