On 7/15/14 1:48 AM, Volker Simonis wrote:
On Mon, Jul 14, 2014 at 10:35 PM, serguei.spit...@oracle.com
<serguei.spit...@oracle.com> wrote:
Hi Volker,
It looks good in general.
But I don't understand all the details.
For instance, your email description of the fix tells that the the event is
posted by:
RuntimeStub::new_runtime_stub() -> CodeBlob::trace_new_stub() ->
JvmtiExport::post_dynamic_code_generated()
I see the new_runtime_stub() call in the generate_throw_exception() but
there is no such call
in the generate_icache_flush() and generate_handler_for_unsafe_access() .
Probably, the StubCodeMark just needs to be removed there.
Could you, please, explain this a little bit?
Hi Serguei,
Thank you for looking at my change. I tried to explain your questions
in my initial mail but maybe I wasn't clear enough:
- in generate_icache_flush() and generate_verify_oop() we DO NOT
GENERATE any stub code. We don't use dynamically generated stubs on
ppc64 for flushing the icache or verifying oops but call C-functions
instead. So there's no need to generate post_dynamic_code_generated()
events for them and also no need for a StubCodeMark.
- for generate_throw_exception() we dynamically generate a runtime
stub instead of an simple stub and for runtime stubs the JVMT dynamic
code event is already generated by RuntimeStub::new_runtime_stub() ->
CodeBlob::trace_new_stub() ->
JvmtiExport::post_dynamic_code_generated(). This is exactly the way
how it works on other CPU architectures. The usage of a StubCodeMark
in generate_throw_exception() was simply a "day one" bug in the ppc64
port.
Thank you for the extra details!
I asked for that as my knowledge in this area is limited.
The fix looks good to me.
I can be a sponsor for integration if needed.
But a Review is still required.
- I haven't changed generate_handler_for_unsafe_access() so I don't
actually understand your concerns.
I accidentally copied a wrong name. Sorry.
I had to copy: generate_verify_oop().
Thanks,
Serguei
generate_handler_for_unsafe_access() correctly contains a StubCodeMark
because it dynamically generates stub code - even if it is just the
output of a "not yet implemented" message.
Regards,
Volker
We also need someone from the compiler team to look at this.
I also included into the cc-list Oleg, who recently touched this area.
Thanks,
Serguei
On 7/14/14 11:24 AM, Volker Simonis wrote:
Hi everybody,
can somebody PLEASE review and sponsor this tiny, ppc64-only change.
Thanks,
Volker
On Tue, Jul 8, 2014 at 5:45 PM, Daniel D. Daugherty
<daniel.daughe...@oracle.com> wrote:
Adding the Serviceability Team since JVM/TI belongs to them.
Dan
On 7/8/14 9:41 AM, Volker Simonis wrote:
Hi,
could somebody please review and push the following small, PPC64-only
change to any of the hs team repositories:
http://cr.openjdk.java.net/~simonis/webrevs/8049441/
https://bugs.openjdk.java.net/browse/JDK-8049441
Background:
For some stubs we actually do not really generate code on PPC64 but
instead we use a native C-function with inline-assembly. If the
generators of these stubs contain a StubCodeMark, they will trigger
JvmtiExport::post_dynamic_code_generated_internal events with a zero
length code size. These events may fool clients like Oprofile which
register for these events (thanks to Maynard Johnson who reported this
- see
http://mail.openjdk.java.net/pipermail/ppc-aix-port-dev/2014-June/002032.html).
This change simply removes the StubCodeMark from
ICacheStubGenerator::generate_icache_flush() and generate_verify_oop()
because they don't generate assembly code. It also removes the
StubCodeMark from generate_throw_exception() because it doesn't really
generate a plain stub but a runtime stub for which the JVMT dynamic
code event is already generated by RuntimeStub::new_runtime_stub() ->
CodeBlob::trace_new_stub() ->
JvmtiExport::post_dynamic_code_generated().
Thank you and best regards,
Volker
