pretty please can we kill the png optimizer?

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pretty please can we kill the png optimizer?

Matthias Klose-6
Hi,

we don't ship cd images anymore, we are not limited to CD sizes, and as long as
we don't hit some 2GB limit, we shouldn't optimize for size.  This "optimizer"
adds for some packages 100% build time, in rare occasions up to 2000%.  This is
not worth the savings.  If we want to optimize for size, this should be done by
test rebuilds and individual patches, not consuming scare buildd resources.

thanks, Matthias

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Re: pretty please can we kill the png optimizer?

Oliver Grawert
hi,
Am Mittwoch, den 12.08.2015, 03:34 +0200 schrieb Matthias Klose:
> Hi,
>
> we don't ship cd images anymore, we are not limited to CD sizes, and as long as
> we don't hit some 2GB limit, we shouldn't optimize for size.  This "optimizer"
> adds for some packages 100% build time, in rare occasions up to 2000%.  This is
> not worth the savings.  If we want to optimize for size, this should be done by
> test rebuilds and individual patches, not consuming scare buildd resources.
>
while this may be true for desktop isos, we are still size constrained
on the phone, if there is anything seeded on the phone that uses the
optimizer today it needs to go on to do so (the phone images are limited
to the size of the cache partition of the phones)

ciao
        oli


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Re: pretty please can we kill the png optimizer?

Sebastien Bacher
In reply to this post by Matthias Klose-6
Le 12/08/2015 03:34, Matthias Klose a écrit :
> Hi,
>
> we don't ship cd images anymore, we are not limited to CD sizes, and as long as
> we don't hit some 2GB limit, we shouldn't optimize for size.

Hey Matthias,

While we are indeed not limited by a CD size we should not let the iso
freely drift because that has a cost (slower to download/install for
users, more bandwith use for our users, less space on the system to use,
etc).
Did anyone measure what difference with/without the png optimizer would
make on the iso/standard install? Without numbers we can't really decide
on the cost/benefit...

Cheers,
Sebastien Bacher

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Re: pretty please can we kill the png optimizer?

Martin Pitt-4
Sebastien Bacher [2015-08-12 12:03 +0200]:
> Did anyone measure what difference with/without the png optimizer would
> make on the iso/standard install? Without numbers we can't really decide
> on the cost/benefit...

Back on natty it was ~ 5.5 MB (compressed size) gain with compressing
PNGs and 7 MB with compressing SVGs.

  https://blueprints.launchpad.net/ubuntu/+spec/performance-desktop-n-install-footprint

There is no reason to believe that the numbers would be dramatically
different these days, i. e. you can expect a 10 to 15 MB gain on a
desktop ISO from this.

Martin
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Re: pretty please can we kill the png optimizer?

Timo Jyrinki-4
In reply to this post by Matthias Klose-6
2015-08-12 4:34 GMT+03:00 Matthias Klose <[hidden email]>:
> we don't ship cd images anymore, we are not limited to CD sizes, and as long as
> we don't hit some 2GB limit, we shouldn't optimize for size.  This "optimizer"
> adds for some packages 100% build time, in rare occasions up to 2000%.  This is
> not worth the savings.  If we want to optimize for size, this should be done by
> test rebuilds and individual patches, not consuming scare buildd resources.

I'd support this, as the PNG repacking is hugely time consuming on
especially armhf Qt builds. If I recall correctly it's pretty near
that 100% in eg qtdeclarative, making it 2h instead of 1h, and very
slow also with for example qtbase amd64. And whenever doing a big
amount of no-change rebuilds, the build times add up.

In test builds I try to remember to use export NO_PNG_PKG_MANGLE := 1
in debian/rules.

It's not that the feature itself is bad, but optipng is just slow for
the gain it brings on average. Just being able to run it utilizing all
CPU:s would probably help, or maybe different parameters.

There are alternative tools in archives like pngquant, but that one is
lossy (funny for a PNG). Some are faster and do better compression,
but are not free software.

-Timo

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Re: pretty please can we kill the png optimizer?

Didier Roche-3
In reply to this post by Martin Pitt-4
Le 12/08/2015 12:15, Martin Pitt a écrit :

> Sebastien Bacher [2015-08-12 12:03 +0200]:
>> Did anyone measure what difference with/without the png optimizer would
>> make on the iso/standard install? Without numbers we can't really decide
>> on the cost/benefit...
> Back on natty it was ~ 5.5 MB (compressed size) gain with compressing
> PNGs and 7 MB with compressing SVGs.
>
>    https://blueprints.launchpad.net/ubuntu/+spec/performance-desktop-n-install-footprint
>
> There is no reason to believe that the numbers would be dramatically
> different these days, i. e. you can expect a 10 to 15 MB gain on a
> desktop ISO from this.
>
> Martin

Is that only iso/image size (so recompressed in the squashfs) or the
gain of an ubuntu install itself, on disk?

Didier

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Re: pretty please can we kill the png optimizer?

Martin Pitt-4
Didier Roche [2015-08-12 12:29 +0200]:

> Le 12/08/2015 12:15, Martin Pitt a écrit :
> >Sebastien Bacher [2015-08-12 12:03 +0200]:
> >>Did anyone measure what difference with/without the png optimizer would
> >>make on the iso/standard install? Without numbers we can't really decide
> >>on the cost/benefit...
> >Back on natty it was ~ 5.5 MB (compressed size) gain with compressing
> >PNGs and 7 MB with compressing SVGs.
> >
> >   https://blueprints.launchpad.net/ubuntu/+spec/performance-desktop-n-install-footprint
> >
> >There is no reason to believe that the numbers would be dramatically
> >different these days, i. e. you can expect a 10 to 15 MB gain on a
> >desktop ISO from this.
> >
> >Martin
>
> Is that only iso/image size (so recompressed in the squashfs) or the gain of
> an ubuntu install itself, on disk?

As I said, "compressed size", i. e. squashfs/deb difference. PNGs
are already compressed so don't make much difference on an install;
SVGs will get quite a bit bigger uncompressed (but I don't have any
numbers).

Martin

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Re: pretty please can we kill the png optimizer?

Mario Limonciello-2
On Wed, Aug 12, 2015 at 5:36 AM Martin Pitt <[hidden email]> wrote:
Didier Roche [2015-08-12 12:29 +0200]:
> Le 12/08/2015 12:15, Martin Pitt a écrit :
> >Sebastien Bacher [2015-08-12 12:03 +0200]:
> >>Did anyone measure what difference with/without the png optimizer would
> >>make on the iso/standard install? Without numbers we can't really decide
> >>on the cost/benefit...
> >Back on natty it was ~ 5.5 MB (compressed size) gain with compressing
> >PNGs and 7 MB with compressing SVGs.
> >
> >   https://blueprints.launchpad.net/ubuntu/+spec/performance-desktop-n-install-footprint
> >
> >There is no reason to believe that the numbers would be dramatically
> >different these days, i. e. you can expect a 10 to 15 MB gain on a
> >desktop ISO from this.
> >
> >Martin
>
> Is that only iso/image size (so recompressed in the squashfs) or the gain of
> an ubuntu install itself, on disk?

As I said, "compressed size", i. e. squashfs/deb difference. PNGs
are already compressed so don't make much difference on an install;
SVGs will get quite a bit bigger uncompressed (but I don't have any
numbers).

Martin

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On the worst offenders, what about working with upstream to get the png optimizations submitted and accepted?  When this happens set up an environment variable in debian/rules to indicate to skip optimization as it's not necessary.



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