RE: [PATCH v2] use xz and gzip on host (outside chroot)

["Moessbauer, Felix" <felix.moessbauer@siemens.com>]

> From: isar-users@googlegroups.com <isar-users@googlegroups.com> On
> Behalf Of Anton Mikanovich
> Sent: Tuesday, August 16, 2022 5:11 PM
> To: Moessbauer, Felix (T CED SES-DE) <felix.moessbauer@siemens.com>;
> isar-users@googlegroups.com
> Cc: Schild, Henning (T CED SES-DE) <henning.schild@siemens.com>; Schmidt,
> Adriaan (T CED SES-DE) <adriaan.schmidt@siemens.com>; Baurzhan
> Ismagulov <ibr@ilbers.de>
> Subject: Re: [PATCH v2] use xz and gzip on host (outside chroot)
> 
> 08.08.2022 10:36, Felix Moessbauer wrote:
> > From: Adriaan Schmidt <adriaan.schmidt@siemens.com>
> >
> > This patch significantly speeds up the final image compression as the
> > compression itself is no longer emulated.
> >
> > For gzip, no additional dep has to be installed on the system, for xz
> > the xz-utils package has to be installed but this will be required
> > from bitbake 2.0 on anyways.
> >
> > Signed-off-by: Adriaan Schmidt <adriaan.schmidt@siemens.com>
> > Acked-by: Felix Moessbauer <felix.moessbauer@siemens.com>
> 
> Hello,
> 
> I've made some investigations to collect compression speed statistics on
> qemuarm64-bullseye Isar target with 490Mb rootfs. Here are the results:
> 
> XZ:
> Buildchroot xz (QEMU):   45.305s
> Host xz:                 18.783s
> 
> GZIP:
> Buildchroot gzip (QEMU):   4m30.155s
> Host gzip:                 1m30.135s
> Buildchroot gzip (native): 1m27.162s
> 
> Buildchroot pigz (QEMU):     32.265s
> Host pigz:                   13.131s

While this already shows the significant speedup, I saw much larger ones when using xz on multi GB images.

> 
> So it looks reasonable to use native compression and we really need to think
> about removing ISAR_CROSS_COMPILE="0" for imager.

I just gave that a try and it somehow magically worked out of the box (on my arm64 image).
Don't know why this was added in the first place.
Let's add Claudius to the discussion as he introduced that.

Just running the compression in the buildchroot-host is not as easy as many things are tightly coupled with the imager (like installing the compression utilities).
But just switching ISAR_CROSS_COMPILE is even simpler and further reduces the amount of work that has to be emulated.

Felix

> We also can try to use parallelized pigz for gzip compression.
>