RFR: JDK-8301661: Enhance os::pd_print_cpu_info on macOS and Windows [v6]

[Matthias Baesken]

On Fri, 17 Feb 2023 08:17:52 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

>> Enhance os::pd_print_cpu_info on macOS and Windows by information about CPU frequency and caches.
>> On Windows , this info can be obtained by the Processor Power Information API or "powerbase" (CallNtPowerInformation , see https://learn.microsoft.com/en-us/windows/win32/api/powerbase/nf-powerbase-callntpowerinformation ); this is available since Windows Server 2003/XP.
>> On macOS, sysctlbyname can be used.
>
> Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Rename variables, adjust output, add a break

Hi David I adjusted the output, renamed some variables and added a break where you suggested.

> In this case shouldn't the function have returned STATUS_BUFFER_TOO_SMALL

I think this would be the case, but I was not sure so I added the check.

> How is the caller supposed to know what size buffer to pass? Are they just supposed to guess and hope it is big enough??

I think this is the same for most of the print_  functions from
src/hotspot/share/runtime/os.hpp
getting a buffer 'buf'  and a buf-length value, they are unfortunately not very specific on the size passed.

https://github.com/openjdk/jdk/blob/master/src/hotspot/share/runtime/os.hpp#L754

  // Print out system information; they are called by fatal error handler.
  // Output format may be different on different platforms.

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PR: https://git.openjdk.org/jdk/pull/12403