On Fri, 24 Feb 2023 10:12:52 GMT, Martin Doerr <mdo...@openjdk.org> wrote:
> > > ~I don't think we've done that much testing with UseSystemMemoryBarrier > > > since it was added~. I'm a bit nervous about turning it on by default > > > since it's currently also used for JNI. Let's see what Robbin thinks. > > > > > > For reliability: On every Oracle tier 5 we run these test two groups: > > vmTestbase_nsk_jvmti, open/test/hotspot/jtreg/:hotspot_runtime For each of > > linux_x64_debug, windows_x64, linux_aarch64_debug with sysmembar on. I > > picked jvmti as this is very heavy on 'JNI'. No issues reported that I know > > about. We also have this test: SystemMembarHandshakeTransitionTest.java > > which only JNI transisition with this options. > > For performance, the heavy lifting is on reader of thread state and the > > only case I have identified is JFR. > > I suggest changing the default now, if there is issues we have time to > > revert it back before RDP1. > > Thanks for your prompt reply! I agree, this is a good time to enable it. Do > you want to do it? We'll support it and run tests on our machines and > platforms. I think JFR users who want a very high sampling rate can switch it > off. Making the flag diagnostic is fine with me, but that shouldn't get > discussed in this PR :-) I will be skiing next week, if you want it now, I suggest you do it, otherwise I can when I'm back. ------------- PR: https://git.openjdk.org/jdk/pull/12708
