makepkg-optimize

makepkg-optimize^AUR is a collection of supplemental tidy, buildenv, and executable scripts for pacman which provide macros for several kinds of optimization in the build() and package() stages.

Note: As with any package in the Arch User Repository, makepkg-optimize^AUR has no official support. You should read, and you may post comments on its AUR page.

Installation

Install makepkg-optimize^AUR and, to make available optimizations requiring them, install backends: openmp, upx, optipng, svgo^AUR, and polly.

Configuration

makepkg-optimize^AUR generates a redundant configuration file, /etc/makepkg-optimize.conf, from your current makepkg.conf(5) configuration.

This file lists supplementary COMPILE FLAGS, BUILD ENVIRONMENT options, GLOBAL PACKAGE OPTIONS, PACKAGE OUTPUT options, and COMPRESSION DEFAULTS, all of which are disabled by default.

Build an optimized package

Warning: Some packages may fail to build with certain optimizations and over-optimization may cause problems for some programs--such as decreased performance and segmentation faults.

After selecting your preferred optimizations, pass the configuration file when building:

$ makepkg -c --config /etc/makepkg-optimize.conf

Tip: Use -c with makepkg to prevent packages reusing stale optimization flags. See Makepkg#Usage.

Note: Profile-guided optimization requires that a package be built and installed twice. The first phase initiates profile generation in $PROFDEST/pkgbase.gen; the second moves them to $PROFDEST/pkgbase.used and applies them.

Build an optimized package in a clean chroot

Alternatively, makepkg-optimize can be used to build optimized packages within a chroot.

Chroot setup

After setting up a chroot, a few additional steps are needed.

Install makepkg-optimize and backends

First, install some of the backends for the optimization macros to the base chroot:

$ arch-nspawn "$CHROOT"/root pacman -S openmp upx optipng polly

Then download and build makepkg-optimize^AUR and svgo^AUR.

To install them in the base chroot, copy their package files into it and install them, e.g.:

# cp svgo-1.2.2-2-any.pkg.tar.xz "$CHROOT"/root/root/
$ arch-nspawn "$CHROOT"/root pacman -U /root/svgo-1.2.2-2-any.pkg.tar.xz

Warning: This voids the warranty on your "clean" chroot!

Using the chroot

Build a package

First, edit $CHROOT/root/etc/makepkg-optimize.conf and select your preferred optimizations.

When building, pass the configuration file to makepkg:

$ makechrootpkg -c -r "$CHROOT" -- -c --config /etc/makepkg-optimize.conf

Building with PGO

The pgo option for BUILDENV enables either generation or application of profiles, depending on if this is the first or second build of the package with this flag enabled. Clean chroot building complicates this because the software is run outside of the chroot to generate profiles, but the profiles need to be applied from inside the chroot when recompiling later. The solution is to bridge the three filesystems with a bind mounted folder.

Create a PGO cache

Create and bind a folder to store profiles:

# mkdir -m 777 {"$CHROOT"/{root,"$USER"},}/mnt/pgo
# mount -o bind {,"$CHROOT"/root}/mnt/pgo
# mount -o bind "$CHROOT"/{root,"$USER"}/mnt/pgo

Tip: Use fstab to bind these folders at boot.

#PGODEST
/full/path/to/$CHROOT/$USER/mnt/pgo/ /mnt/pgo/ none bind,x-gvfs-hide 0 0
/mnt/pgo/ /full/path/to/$CHROOT/root/mnt/pgo/ none bind,x-gvfs-hide 0 0

Note: Type out the full path to the chroot pgo directories, without using any $VARIABLES

Edit $CHROOT/root/etc/makepkg-optimize.conf and set PROFDEST=/mnt/pgo.

Profile a program

Build, then install the package and test-run its executables.

Note: Profiles are generated on program exit(). Persistent daemons, such as systemd, may require a reboot to produce profiles.

After thoroughly utilizing the software, close it, then rebuild and reinstall its package.