Re: [Patch] Losing many samples when profiling multiple JVMs

On Wed, 2015-07-15 at 15:03 -0400, William Cohen wrote:
> 
> I tried the test on rhel7 ppc64 and it doesn't work because of the way
> that calls operates.  The ppc64 generated code is treating the address
> returned by 
> initialize_anon_func as a pointer to a descriptor rather than the
> address that the branch should branch to.  The first 3 double word in
> the generated anon_func are used as a descriptor and the branch goes
> off to the wrong location
> (https://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi-1.9.html#FUNC-DES)
> 
> Is this code working on ppc64le? How is the code being compiled on
> your machine? Or does it have a similar problem?  Any suggestions on
> how to best address this?


Note that the PPC64le platform (which uses the ELF ABIv2) does not use
function descriptors, so it is possible the code actually just works on
ppc64le.
I've not actually tried this patch, but saw the comment go past, and
thought I should chime in in case folks were off scratching their heads
in confusion.. :-)
  I don't immediately see any existing if/else logic in the oprofile
code that specifically handles those cases differently, aside from the
description I see at the top of bfd_info::get_synth_symbols() in
 oprofile/libutil++/bfd_support.cpp

Thanks, 
-Will (Schmidt)


------------------------------------------------------------------------------
Don't Limit Your Business. Reach for the Cloud.
GigeNET's Cloud Solutions provide you with the tools and support that
you need to offload your IT needs and focus on growing your business.
Configured For All Businesses. Start Your Cloud Today.
https://www.gigenetcloud.com/