RFR: 8354938: ZGC: Disable UseNUMA when ZFakeNUMA is used

Tue Apr 22 06:07:40 UTC 2025

On Thu, 17 Apr 2025 12:00:27 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

> ZFakeNUMA is used to fake a number of NUMA nodes within ZGC. The intention was to make ZFakeNUMA mutually exclusive with UseNUMA, but the current code allows the user to enable UseNUMA and set ZFakeNUMA, which will trigger to the "mutual exclusion" assert in ZNUMA::initialize.
> 
> Verified on NUMA machine with -XX:+UseNUMA -XX:ZFakeNUMA=<count>. Will run this through our lower tiers.

lgtm. 

In the future we could probably make UseNUMA work with ZFakeNUMA.

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Marked as reviewed by aboldtch (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24721#pullrequestreview-2782853524