[crac] RFR: RFC: -XX:CPUFeatures=0xnumber for CPU migration [v24]

[Jan Kratochvil]

On Wed, 31 May 2023 09:47:17 GMT, Anton Kozlov <akozlov at openjdk.org> wrote:

>> Jan Kratochvil has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   +-XX:CPUFeatures=ignore
>
> src/hotspot/os/linux/os_linux.cpp line 5962:
> 
>> 5960:   initialize_processor_count();
>> 5961:   if (_cpu_to_node != NULL)
>> 5962:     rebuild_cpu_to_node_map();
> 
> It seems the only place where number of processors is updated, so it's not clear how safe the operation. Please add a debug option for processor count update, I propose that to be disabled by default.

OK, moved under `-XX:+CRaCCPUCountInit`. It was crashing (asserting IIRC) for me when moving between 4 and 20 vCPUs but I was unable to reproduce it now.

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PR Review Comment: https://git.openjdk.org/crac/pull/41#discussion_r1213275788