On Mon, 28 Oct 2024 16:12:39 GMT, Robert Toyonaga <d...@openjdk.org> wrote:
>> ### Summary >> This PR just replaces `ThreadCritical` with a lock specific to NMT. >> `ThreadCritical` is a big lock and is unnecessary for the purposes of NMT. >> I've implemented the new lock with a semaphore so that it can be used early >> before VM init. There is also the possibility of adding assertions in >> places we expect NMT to have synchronization. I haven't added assertions yet >> in many places because some code paths such as the (NMT tests) don't lock >> yet. I think it makes sense to close any gaps in locking in another PR in >> which I can also add more assertions. >> >> Testing: >> - hotspot_nmt >> - gtest:VirtualSpace >> - tier1 > > Robert Toyonaga has updated the pull request incrementally with two > additional commits since the last revision: > > - add a comment explaining lock rank > - remove unnecessary dropping of tracking level We should get rid of this awful value correcting for arenas. I get headaches trying to think about this every time. To remind everyone including me, some of the stuff is explained here: [complex](https://bugs.openjdk.org/browse/JDK-8325890) . About locking around os::free - not sure if we can do this. Are all paths inside os::free lock free? It does call NMT. I think all cases inside NMT that touches are lock free, but am not sure. Have to think about this a biot. ------------- PR Comment: https://git.openjdk.org/jdk/pull/20852#issuecomment-2447570321
