On 12/12/2019 1:07 am, Reingruber, Richard wrote:
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!
Apologies the above should read:
"Most of the details here are in areas I *can't* comment on in detail ..."
David
> 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
