RFR: 8283199: Linux os::cpu_microcode_revision() stalls cold startup [v3]

[David Holmes]

On Mon, 21 Mar 2022 09:25:38 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> I looked through Linux kernel sources, and I believe it was added by https://github.com/torvalds/linux/commit/9a4b9efa1d39d7d31bed08fbe5a9b2a03b2759d4 back in 2006, and landed in 2.6.19. So even a relatively ancient RHEL 6 already has it.

My "Oracle Linux Server release 7.9" doesn't have it. But I'm not sure if I'm virtualized or not ... I suspect yes.

>> src/hotspot/os_cpu/linux_x86/os_linux_x86.cpp line 475:
>> 
>>> 473:         sscanf(data, "%x", &result);
>>> 474:       }
>>> 475:       fclose(fp);
>> 
>> The diff would be much simpler if you added a return here and so avoided the need for the if statement below.
>
> See new commit.

Yeah that change didn't really help.

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PR: https://git.openjdk.java.net/jdk/pull/7825