[LLVMdev] Announcement - A tool to convert Perf profiles to use with LLVM's sample profiler

[Eric Christopher]

Awesome! Thanks Diego!

-eric

On Tue, Apr 15, 2014 at 10:38 AM, Diego Novillo <dnovillo at google.com> wrote:
>
> I'm glad to announce the availability of the AutoFDO converter for LLVM.
> This tool reads a profile generated with Linux Perf
> (https://perf.wiki.kernel.org/) and converts it into a format readable with
> LLVM's sample-based profiler. The converter shares a significant amount of
> code with GCC's converter tool (authored by Dehao Chen), so we can support
> both compilers with it.
>
> At this time, I'm looking for volunteers to try out the tool and use it with
> their own code. There will be missing documentation, sharp edges and other
> issues typical of a tool that so far has had limited use.
>
> To download and build the converter:
>
> $ git clone https://github.com/google/autofdo.git autofdo
> $ cd autofdo && ./configure && make
>
> Note that you will need a compiler with C++11 support (either gcc 4.7+ or a
> recent Clang/LLVM).
>
> To use the converter, you need to use Perf with a kernel that supports LBR
> (any kernel post 3.4 should suffice) and LLVM from trunk (there is some
> support in the 3.4 release, but there were changes post 3.4 that are only
> present in trunk).  The workflow is:
>
> $ clang++ -O2 -gline-tables-only code.cc -o code
> $ perf record -b ./code
> $ create_llvm_prof --binary=./code --out=code.prof
> $ clang++ -O2 -fprofile-sample-use=code.prof code.cc -o code
>
> The second version of 'code' should run faster than the first one. In
> theory.
>
> For issues with the tool itself, please use the issue tracker in github
> (https://github.com/google/autofdo/issues). There is also a mailing list
> where you can ask questions about it
> (https://groups.google.com/forum/#!forum/autofdo).
>
>
> Thanks. Diego.
>
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