Re: [systemd-devel] lto issues
On Tue, Aug 06, 2019 at 09:34:36AM +0200, Michael Biebl wrote:
> Am Di., 6. Aug. 2019 um 09:26 Uhr schrieb Zbigniew Jędrzejewski-Szmek
> :
> >
> > On Sat, Aug 03, 2019 at 07:03:47PM +0200, Michael Biebl wrote:
> > > Hi,
> > >
> > > today I tried compiling systemd v242 (on Debian sid) once using lto
> > > (-Db_lto=true) and once without lto (-Db_lto=false).
> > >
> > > The lto build took approximately twice as long on my laptop (using
> > > dpkg-buildpackage, which introduces a bit of overhead):
> > >
> > > lto:
> > > real 11m22,605s
> > > user 37m9,675s
> > > sys 2m51,041s
> > >
> > > nolto:
> > > real 6m35,615s
> > > user 18m51,782s
> > > sys 2m12,934s
> > >
> > > That's kinda expected. What suprised me though is that using lto
> > > produced larger binaries:
> >
> > I built systemd in F31 (-Doptimization=2 -Db_lto=true/false, and I saw
> > a big increase in binary sizes *before stripping*. After stripping,
> > binaries with lto=true are smaller:
> >
> > $ ls -l build-rawhide{,-lto}/{systemd,src/shared/libsystemd-shared-243.so}
> > 7116384 Aug 6 09:08 build-rawhide/systemd*
> > 11951256 Aug 6 09:07 build-rawhide/src/shared/libsystemd-shared-243.so*
> > 1594912 Aug 6 09:12 build-rawhide-lto/systemd*
> > 3167096 Aug 6 09:11
> > build-rawhide-lto/src/shared/libsystemd-shared-243.so*
> > $ strip build-rawhide{,-lto}/{systemd,src/shared/libsystemd-shared-243.so}
> > $ ls -l build-rawhide{,-lto}/{systemd,src/shared/libsystemd-shared-243.so}
> > 1439640 Aug 6 09:19 build-rawhide/systemd*
> > 2806456 Aug 6 09:19 build-rawhide/src/shared/libsystemd-shared-243.so*
> > 1370008 Aug 6 09:19 build-rawhide-lto/systemd*
> > 2806288 Aug 6 09:19
> > build-rawhide-lto/src/shared/libsystemd-shared-243.so*
>
>
> The sizes I posted i.e. the debdiff is after stripping.
>
> gcc --version
> gcc (Debian 8.3.0-19) 8.3.0
> Copyright (C) 2018 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions. There is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
>
> ld --version
> GNU ld (GNU Binutils for Debian) 2.32.51.20190727
> Copyright (C) 2019 Free Software Foundation, Inc.
> This program is free software; you may redistribute it under the terms of
> the GNU General Public License version 3 or (at your option) a later version.
>
> So with the toolchain I have, mostly has downsides. The only benefit
> it seems to have is that it optimizes unnecessary library dependencies
> away (see how the udev subpackage does not depend on libcap2 (>=
> 1:2.10), libidn2-0 (>= 0.6)
In Fedora, lto seems to have good returns. The final package size was
~10% smaller. We disabled it for a while because there were linking
failures, but I think it's all resolved now.
I forgot to mention. In my test:
gcc-9.1.1-2.fc31.1.x86_64
binutils-2.32-19.fc31.x86_64
Zbyszek
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Re: [systemd-devel] lto issues
On Sa, 03.08.19 19:03, Michael Biebl (mbi...@gmail.com) wrote: > Hi, > > today I tried compiling systemd v242 (on Debian sid) once using lto > (-Db_lto=true) and once without lto (-Db_lto=false). > > The lto build took approximately twice as long on my laptop (using > dpkg-buildpackage, which introduces a bit of overhead): > > lto: > real 11m22,605s > user 37m9,675s > sys 2m51,041s > > nolto: > real 6m35,615s > user 18m51,782s > sys 2m12,934s > > That's kinda expected. What suprised me though is that using lto > produced larger binaries: Have you pinged the toolchain maintainers of your distro about this? Note that systemd doesn't really do much lto stuff on its own anymore, it's now entirely between meson and your toolchain afaics. Lennart -- Lennart Poettering, Berlin ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] lto issues
Am Di., 6. Aug. 2019 um 09:26 Uhr schrieb Zbigniew Jędrzejewski-Szmek
:
>
> On Sat, Aug 03, 2019 at 07:03:47PM +0200, Michael Biebl wrote:
> > Hi,
> >
> > today I tried compiling systemd v242 (on Debian sid) once using lto
> > (-Db_lto=true) and once without lto (-Db_lto=false).
> >
> > The lto build took approximately twice as long on my laptop (using
> > dpkg-buildpackage, which introduces a bit of overhead):
> >
> > lto:
> > real 11m22,605s
> > user 37m9,675s
> > sys 2m51,041s
> >
> > nolto:
> > real 6m35,615s
> > user 18m51,782s
> > sys 2m12,934s
> >
> > That's kinda expected. What suprised me though is that using lto
> > produced larger binaries:
>
> I built systemd in F31 (-Doptimization=2 -Db_lto=true/false, and I saw
> a big increase in binary sizes *before stripping*. After stripping,
> binaries with lto=true are smaller:
>
> $ ls -l build-rawhide{,-lto}/{systemd,src/shared/libsystemd-shared-243.so}
> 7116384 Aug 6 09:08 build-rawhide/systemd*
> 11951256 Aug 6 09:07 build-rawhide/src/shared/libsystemd-shared-243.so*
> 1594912 Aug 6 09:12 build-rawhide-lto/systemd*
> 3167096 Aug 6 09:11 build-rawhide-lto/src/shared/libsystemd-shared-243.so*
> $ strip build-rawhide{,-lto}/{systemd,src/shared/libsystemd-shared-243.so}
> $ ls -l build-rawhide{,-lto}/{systemd,src/shared/libsystemd-shared-243.so}
> 1439640 Aug 6 09:19 build-rawhide/systemd*
> 2806456 Aug 6 09:19 build-rawhide/src/shared/libsystemd-shared-243.so*
> 1370008 Aug 6 09:19 build-rawhide-lto/systemd*
> 2806288 Aug 6 09:19 build-rawhide-lto/src/shared/libsystemd-shared-243.so*
The sizes I posted i.e. the debdiff is after stripping.
gcc --version
gcc (Debian 8.3.0-19) 8.3.0
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
ld --version
GNU ld (GNU Binutils for Debian) 2.32.51.20190727
Copyright (C) 2019 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or (at your option) a later version.
So with the toolchain I have, mostly has downsides. The only benefit
it seems to have is that it optimizes unnecessary library dependencies
away (see how the udev subpackage does not depend on libcap2 (>=
1:2.10), libidn2-0 (>= 0.6)
--
Why is it that all of the instruments seeking intelligent life in the
universe are pointed away from Earth?
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Re: [systemd-devel] lto issues
On Sat, Aug 03, 2019 at 07:03:47PM +0200, Michael Biebl wrote:
> Hi,
>
> today I tried compiling systemd v242 (on Debian sid) once using lto
> (-Db_lto=true) and once without lto (-Db_lto=false).
>
> The lto build took approximately twice as long on my laptop (using
> dpkg-buildpackage, which introduces a bit of overhead):
>
> lto:
> real 11m22,605s
> user 37m9,675s
> sys 2m51,041s
>
> nolto:
> real 6m35,615s
> user 18m51,782s
> sys 2m12,934s
>
> That's kinda expected. What suprised me though is that using lto
> produced larger binaries:
I built systemd in F31 (-Doptimization=2 -Db_lto=true/false, and I saw
a big increase in binary sizes *before stripping*. After stripping,
binaries with lto=true are smaller:
$ ls -l build-rawhide{,-lto}/{systemd,src/shared/libsystemd-shared-243.so}
7116384 Aug 6 09:08 build-rawhide/systemd*
11951256 Aug 6 09:07 build-rawhide/src/shared/libsystemd-shared-243.so*
1594912 Aug 6 09:12 build-rawhide-lto/systemd*
3167096 Aug 6 09:11 build-rawhide-lto/src/shared/libsystemd-shared-243.so*
$ strip build-rawhide{,-lto}/{systemd,src/shared/libsystemd-shared-243.so}
$ ls -l build-rawhide{,-lto}/{systemd,src/shared/libsystemd-shared-243.so}
1439640 Aug 6 09:19 build-rawhide/systemd*
2806456 Aug 6 09:19 build-rawhide/src/shared/libsystemd-shared-243.so*
1370008 Aug 6 09:19 build-rawhide-lto/systemd*
2806288 Aug 6 09:19 build-rawhide-lto/src/shared/libsystemd-shared-243.so*
Zbyszek
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