[jdk17u-dev] RFR: 8283199: Linux os::cpu_microcode_revision() stalls cold startup

[Aleksey Shipilev]

On Mon, 24 Oct 2022 09:23:07 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Unclean backport to fix the startup time regression.
> 
> The backport is not clean, because [JDK-8238161](https://bugs.openjdk.org/browse/JDK-8238161) is not present in JDK 17, and thus we have `fopen` instead of `os::fopen` in these hunks. I changed the code back to `fopen` to be consistent with the rest of JDK 17.
> 
> Verified the startup time improves, using the scripts from the issue.
> 
> 
> # Before
> real	0m0.042s
> real	0m0.043s
> real	0m0.043s
> 
> # After
> real	0m0.025s
> real	0m0.024s
> real	0m0.024s
> 
> 
> Additional testing:
>  - [x] Linux x86_64 fastdebug `tier1`

Got the push approval.

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PR: https://git.openjdk.org/jdk17u-dev/pull/820