On Fri, 24 Feb 2023 07:39:15 GMT, Robbin Ehn <r...@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 :-) ------------- PR: https://git.openjdk.org/jdk/pull/12708
