Re: Compiling binaries with PGO

[Matthias Klose <doko@debian.org>]

On 09.07.2018 12:13, Alexander Zaitsev wrote:
> Hello.
>
> As far as I know binaries in Debian repositories most binaries are compiled without
> PGO (profile-guided optimization). Also I don't know any LInux-based OS
> where all (or significant part) binaries are precompiled with PGO. With PGO we
> can improve
> performance of binaries for typical use-cases without compiling for some
> specific architecture (so binaries with PGO will be architecture-independent).
>
> Question: why PGO isn't used by maintainers for packages? Lack of
> profile data for compilation with PGO? Isn't interested for
> mainatainers? Lack of build resources? Something else? Will you try to use PGO
> for your packages,
> if will be available repository with profile data for different
> applications, where you can pick profile data for your application,
> recompile package with this information and, probably, increase
> performance of your application?

it is used to some extent. E.g. the python interpreter packages are built using 
PGO/LTO optimization on some architectures, and some upstreams support building 
using PGO as well.  You need to find some way to create the profile data, which 
usually requires some extra packaging work.  There is also autofdo, using a more 
general profile data format suitable for both GCC and LLVM, so you could try to 
include that data into the packaging, and use it in the build process.

Don't assume too much speed improvements. I usually see around 3-6%.

Matthias