Hi David,
> Most of the details here are in areas I can comment on in detail, but I
> did take an initial general look at things.
Thanks for taking the time!
> The only thing that jumped out at me is that I think the
> DeoptimizeObjectsALotThread should be a hidden thread.
>
> + bool is_hidden_from_external_view() const { return true; }
Yes, it should. Will add the method like above.
> Also I don't see any testing of the DeoptimizeObjectsALotThread. Without
> active testing this will just bit-rot.
DeoptimizeObjectsALot is meant for stress testing with a larger workload. I
will add a minimal test
to keep it fresh.
> Also on the tests I don't understand your @requires clause:
>
> @requires ((vm.compMode != "Xcomp") & vm.compiler2.enabled &
> (vm.opt.TieredCompilation != true))
>
> This seems to require that TieredCompilation is disabled, but tiered is
> our normal mode of operation. ??
>
I removed the clause. I guess I wanted to target the tests towards the code
they are supposed to
test, and it's easier to analyze failures w/o tiered compilation and with just
one compiler thread.
Additionally I will make use of
compiler.whitebox.CompilerWhiteBoxTest.THRESHOLD in the tests.
Thanks,
Richard.
-----Original Message-----
From: David Holmes <david.hol...@oracle.com>
Sent: Mittwoch, 11. Dezember 2019 08:03
To: Reingruber, Richard <richard.reingru...@sap.com>;
serviceability-dev@openjdk.java.net; hotspot-compiler-...@openjdk.java.net;
hotspot-runtime-...@openjdk.java.net
Subject: Re: RFR(L) 8227745: Enable Escape Analysis for Better Performance in
the Presence of JVMTI Agents
Hi Richard,
On 11/12/2019 7:45 am, Reingruber, Richard wrote:
> Hi,
>
> I would like to get reviews please for
>
> http://cr.openjdk.java.net/~rrich/webrevs/2019/8227745/webrev.3/
>
> Corresponding RFE:
> https://bugs.openjdk.java.net/browse/JDK-8227745
>
> Fixes also https://bugs.openjdk.java.net/browse/JDK-8233915
> And potentially https://bugs.openjdk.java.net/browse/JDK-8214584 [1]
>
> Vladimir Kozlov kindly put webrev.3 through tier1-8 testing without issues
> (thanks!). In addition the
> change is being tested at SAP since I posted the first RFR some months ago.
>
> The intention of this enhancement is to benefit performance wise from escape
> analysis even if JVMTI
> agents request capabilities that allow them to access local variable values.
> E.g. if you start-up
> with -agentlib:jdwp=transport=dt_socket,server=y,suspend=n, then escape
> analysis is disabled right
> from the beginning, well before a debugger attaches -- if ever one should do
> so. With the
> enhancement, escape analysis will remain enabled until and after a debugger
> attaches. EA based
> optimizations are reverted just before an agent acquires the reference to an
> object. In the JBS item
> you'll find more details.
Most of the details here are in areas I can comment on in detail, but I
did take an initial general look at things.
The only thing that jumped out at me is that I think the
DeoptimizeObjectsALotThread should be a hidden thread.
+ bool is_hidden_from_external_view() const { return true; }
Also I don't see any testing of the DeoptimizeObjectsALotThread. Without
active testing this will just bit-rot.
Also on the tests I don't understand your @requires clause:
@requires ((vm.compMode != "Xcomp") & vm.compiler2.enabled &
(vm.opt.TieredCompilation != true))
This seems to require that TieredCompilation is disabled, but tiered is
our normal mode of operation. ??
Thanks,
David
> Thanks,
> Richard.
>
> [1] Experimental fix for JDK-8214584 based on JDK-8227745
>
> http://cr.openjdk.java.net/~rrich/webrevs/2019/8214584/experiment_v1.patch
>
