[sugar] Moving to metacity with composition (was: Preparing for the feature freeze)

[Tomeu Vizoso]

On Tue, Jun 3, 2008 at 11:54 AM, Marco Pesenti Gritti
<mpgritti at gmail.com> wrote:
> On Tue, Jun 3, 2008 at 11:45 AM, Tomeu Vizoso <tomeu at tomeuvizoso.net> wrote:
>>> Priority 2. I would love to have it but it might be too late, given
>>> that Sayamindu experimentation run into interesting problems.
>>
>> A nice thing about this is that little changes to sugar are expected
>> to be needed, so it's easy to swap-in swap-out, perhaps in a quick
>> 8.2.1 release?
>
> Well, if we go for the fullscreen hint approach, it will need changes
> to all the non-python activities, so it would be pretty invasive.

Ouch, is that acceptable? What will happen when kids try to run an old activity?

>>>> activate composition (eToys and
>>>> Record have trouble with this).
>>>
>>> Priority 1. Can we actually do this given the memory constraints?
>>
>> We'll be saving 3.5MB per python activity with the prefork trick, and
>> in the worst case we would be having a penalty of 2MB per fullscreen
>> window because of composition.
>
> Bernando was saying that this is not possible because of *video*
> memory constraints.

Hmm, but not all those pixmaps will be kept in video mem, right? If
so, then I don't get why the faster builds work so fine.

Anyway, Martin Dengler did an awesome job measuring the mem hit in
matchbox, so I guess we should reread it and maybe redo the tests with
metacity:

http://lists.laptop.org/pipermail/sugar/2008-March/004718.html

Sayamindu, you say you got OOM problems after activating composition,
can you check where that memory is going? Or might be the X server
crashing instead?

>> If we only keep the active activity
>> composited, we could limit this to a total of 4MB with peaks of 6MB
>> (desktop window + active activity + inactive activity while we take
>> the screenshot).
>
> I would like to see a proof of concept of this approach.

Me too ;)

Just for the record, I'm not strongly advocating for composition in
8.2. I just happen to think that it could bring a lot of value and we
should consider carefully if it's doable or not.

Cheers,

Tomeu