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List:       openjdk-serviceability-dev
Subject:    Re: RFR: 8320239: add dynamic switch for JvmtiVTMSTransitionDisabler sync protocol [v3]
From:       Serguei Spitsyn <sspitsyn () openjdk ! org>
Date:       2023-11-30 17:01:22
Message-ID: 5g-8z-piS7aZSv_WxK0Nq4i3nCB6nCban162zPn73dQ=.678b827b-0363-44a5-8782-a1d0802e1b6a () github ! com
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On Thu, 30 Nov 2023 07:34:23 GMT, Serguei Spitsyn <sspitsyn@openjdk.org> wrote:

> > This is an update for a performance/scalability enhancement.
> > 
> > The `JvmtiVTMSTransitionDisabler`sync protocol is on a performance critical path \
> > of the virtual threads mount state transitions (VTMS transitions). It has a \
> > noticeable performance overhead (about 10%) which contributes to the combined \
> > JVMTI performance overhead when Java apps are executed with loaded JVMTI agents. 
> > Please, also see another/related performance issue which contributes around 70% \
> > of total performance overhead: \
> > [8308614](https://bugs.openjdk.org/browse/JDK-8308614): Enabling JVMTI ClassLoad \
> > event slows down vthread creation by factor 10 
> > Testing:
> > - Ran mach5 tiers 1-6 with no regressions noticed.
> 
> Serguei Spitsyn has updated the pull request incrementally with one additional \
> commit since the last revision: 
> review: addressed a race condition

Leonid, Alex and Patricio thank you for review!

-------------

PR Comment: https://git.openjdk.org/jdk/pull/16688#issuecomment-1834166897


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