llvm dev - Mar 2013 - [LLVMdev] Profiling LLVM JIT code

Hey guys,

I am currently working on a project that uses JIT compilation to compile
incoming user requests to native code. Are there some best practises
related to profiling the generated code?

My project uses gperftools pprof for profiling etc. Is there a way to hook
the two up? Are there any other profiling method that works? This page
describes how to debug JIT code with GDB. I wonder if something similar
could be done for gperftools/pprof?

Regards,
-- Priyendra
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Hi Priyendra,

There is support for oprofile and Intel(r) VTune(tm) Performance Analyzer, but
either one needs to be explicitly turned on during the build process.  If you
use MCJIT (as opposed to the older JIT) then oprofile support isn't in place
yet.

Both of these work by providing a JITEventListener that receives notification
when new code is emitted and hooks it up to the profiling tool via some
tool-specific notification API.  I'm not familiar with pprof, but it
probably wouldn't be very difficult to write a new event listener to add
support for pprof.

You can find the oprofile code in 'llvm/lib/ExecutionEngine/OProfileJIT'
to use as an example.

-Andy

From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On
Behalf Of Priyendra Deshwal
Sent: Sunday, March 03, 2013 3:11 AM
To: llvmdev at cs.uiuc.edu
Subject: [LLVMdev] Profiling LLVM JIT code

Hey guys,

I am currently working on a project that uses JIT compilation to compile
incoming user requests to native code. Are there some best practises related to
profiling the generated code?

My project uses gperftools pprof for profiling etc. Is there a way to hook the
two up? Are there any other profiling method that works? This page describes how
to debug JIT code with GDB. I wonder if something similar could be done for
gperftools/pprof?

Regards,
-- Priyendra

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Thanks for the info. I am using old JIT. So that should not be a problem.

I will take a look at using oprofile. I have never used it - so will be
somewhat of a learning curve.

I notice that the configure script has a --with-oprofile option. In
addition to enabling that, is there something else that also needs to be
done? My copy of LLVM is compiled with --enable-optimized. Will
--with-oprofile work fine with that or should I disable optimized?

Regards,
-- Priyendra

On Mon, Mar 4, 2013 at 11:54 AM, Kaylor, Andrew <andrew.kaylor at
intel.com>wrote:
>  Hi Priyendra,****
>
> ** **
>
> There is support for oprofile and Intel® VTune™ Performance Analyzer, but
> either one needs to be explicitly turned on during the build process.  If
> you use MCJIT (as opposed to the older JIT) then oprofile support isn’t in
> place yet.****
>
> ** **
>
> Both of these work by providing a JITEventListener that receives
> notification when new code is emitted and hooks it up to the profiling tool
> via some tool-specific notification API.  I’m not familiar with pprof, but
> it probably wouldn’t be very difficult to write a new event listener to add
> support for pprof.****
>
> ** **
>
> You can find the oprofile code in ‘llvm/lib/ExecutionEngine/OProfileJIT’
> to use as an example.****
>
> ** **
>
> -Andy****
>
> ** **
>
> *From:* llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at
cs.uiuc.edu] *On
> Behalf Of *Priyendra Deshwal
> *Sent:* Sunday, March 03, 2013 3:11 AM
> *To:* llvmdev at cs.uiuc.edu
> *Subject:* [LLVMdev] Profiling LLVM JIT code****
>
> ** **
>
> Hey guys,****
>
> ** **
>
> I am currently working on a project that uses JIT compilation to compile
> incoming user requests to native code. Are there some best practises
> related to profiling the generated code?****
>
> ** **
>
> My project uses gperftools pprof for profiling etc. Is there a way to hook
> the two up? Are there any other profiling method that works? This page
> describes how to debug JIT code with GDB. I wonder if something similar
> could be done for gperftools/pprof?****
>
> ** **
>
> Regards,****
>
> -- Priyendra****
>
> ** **
>
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