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List:       openjdk-serviceability-dev
Subject:    Re: RFR: 8323680: SA PointerFinder code can do a better job of leveraging existing code to determine
From:       Chris Plummer <cjplummer () openjdk ! org>
Date:       2024-01-30 19:53:06
Message-ID: yPQF3hPQpl5Z0QO5hGoiPOIxN1NOT51vCsdEL2yCRpM=.e642e44a-e2cc-4434-9d98-c5ca2b6a9408 () github ! com
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On Fri, 26 Jan 2024 21:20:04 GMT, Chris Plummer <cjplummer@openjdk.org> wrote:

> > In PointerFinder.java we have some code to determine if a pointer is in a TLAB, \
> > but it only executes for the SerialGC. It should work for all GCs, so I moved the \
> > code out of the SerialGC block. 
> > I also cleaned up the printing in PointerLocation. java a bit so when not using \
> > verbose mode not as much info about the tlab address is printed. This is \
> > consistent with other addresses, such as java stack addresses, which is what I \
> > modeled this change on. 
> > It's hard to test this change since it is hard to consistently get an address to \
> > be in the tlab. I wrote a little test program that just sits in a loop doing \
> > allocations. I attached to it with clhsdb and ran the threadcontext command, \
> > which does a fincpc on each register. About half the time the main thread was \
> > suspended in a frame where some registers where pointing into the tlab, and I \
> > confirmed this was the case for both SerialGC and G1. Here's an example of one \
> > register with verbose off and verbose on: 
> > rsi: 0x000000008a5d4448: In TLAB for thread "main" \
> > sun.jvm.hotspot.runtime.JavaThread@0x00007ffa24029000 
> > rsi: 0x000000008a5d4448: In TLAB for thread ("main" #1 prio=5 \
> >                 tid=0x00007ffa24029000 nid=25392 runnable [0x0000000000000000]
> > java.lang.Thread.State: RUNNABLE
> > JavaThread state: _thread_in_java
> > )  [0x000000008a5d4448,0x000000008ab724b8,0x000000008b0c0250,{0x000000008b0c0490})
> >  
> > For testing I ran all tier1, tier2, and tier5 svc tests (still in progress)
> 
> Chris Plummer has updated the pull request incrementally with one additional commit \
> since the last revision: 
> Get rid of inTLAB field. Not needed

Thanks for the review Kevin. Can I get one more review please? Thanks!

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

PR Comment: https://git.openjdk.org/jdk/pull/17494#issuecomment-1917766779


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