On 25 February 2018 at 12:30, Zbigniew Jędrzejewski-Szmek
<zbyszek(a)in.waw.pl> wrote:
On Sun, Feb 25, 2018 at 01:19:24PM +0100, Florian Weimer wrote:
> On 02/25/2018 12:45 PM, Zbigniew Jędrzejewski-Szmek wrote:
> >>What's our current take on using LTO for Fedora package builds?
>
> >systemd would like to use it.
>
> Why? What are the benefits?
There's a small change in size. When I tested recently it was ~7%, but
it was higher in the past. Fedora builds usually enable almost all optional
code, but if some parts are disabled (which happens also in RHEL), I think
the gains are bigger.
Apart from that, we hope the code is faster, which is the usual
motivation for flto.
BTW size. Did you try to compile systemd with optimisation for size (-Os)?
There are many Linux packages which should be optimised for size
because they provide binaries which are speed critical like boot
loaders and boot tools (grub, lilo, gubby) some diagnostics and system
tools (dmidecode, strace, parted, shadow-utils, util-linux, lvm, mdadm
..)
In many cases optimisations for size provides faster code at it has
lower probability generate CPU cache misses.
kloczek
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