llvm dev - Jun 2013 - [LLVMdev] RFC - Profile Guided Optimization in LLVM

>
> After the basic profile-based transformations are working, I would like to
> add new sources of profile.  Mainly, I am thinking of implementing Auto
> FDO.
>
For those who are not familiar with what autoFDO is -- Auto FDO is
originally called Sample Based FDO. Its main author is Dehao Chen @google,
and Robert Hundt is the one of the main pushers of technology in Google.
The latest incarnation of this technology uses LBR events available on
Nehalem and above.
http://www.computer.org/csdl/trans/tc/2013/02/ttc2013020376-abs.html

Cheers,

David
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Apple folks are also gearing up to push on the PGO front. We are primarily
interested in using instrumentation, rather than sampling, to collect profile
info. However, I suspect the way profile ended up being used in the various
optimization and codegen passes would be largely similar.

There is also some interests in pursuing profile directed specialization. But
that can wait. I think it makes sense for us to get together and discuss our
plans to make sure there won't be duplication of efforts.

Evan

Sent from my iPad

On Jun 12, 2013, at 4:26 PM, Xinliang David Li <xinliangli at gmail.com>
wrote:
> 
>> 
>> After the basic profile-based transformations are working, I would like
to add new sources of profile.  Mainly, I am thinking of implementing Auto FDO.
> 
> For those who are not familiar with what autoFDO is -- Auto FDO is
originally called Sample Based FDO. Its main author is Dehao Chen @google, and
Robert Hundt is the one of the main pushers of technology in Google. The latest
incarnation of this technology uses LBR events available on Nehalem and above. 
http://www.computer.org/csdl/trans/tc/2013/02/ttc2013020376-abs.html
> 
> Cheers,
> 
> David
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
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On 2013-06-15 14:18 , Evan Cheng wrote:
> Apple folks are also gearing up to push on the PGO front. We are 
> primarily interested in using instrumentation, rather than sampling, 
> to collect profile info. However, I suspect the way profile ended up 
> being used in the various optimization and codegen passes would be 
> largely similar.
>
Excellent!  We are initially interested in instrumentation, as well.  
This is where we draw most of our performance with GCC. Sampling is 
showing a lot of promise, however.  And it really is not much different 
than instrumentation.  Most of what changes is the source of profile data.
> There is also some interests in pursuing profile directed 
> specialization. But that can wait. I think it makes sense for us to 
> get together and discuss our plans to make sure there won't be 
> duplication of efforts.
Sure. My initial plan is fairly simple.  Triage the existing 
instrumentation code and see what needs fixing.  I'm starting this in 
the next week or so.  What are your plans?


Diego.
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