[sugar] [PATCH] screenshots hurt

[Greg Smith]

Hi Tomeu,

Pardon my ignorance but what are screenshots in this context? rtfm links 
welcome too.

Explain what is different about what the end user would see on the 
screen before and after this change. Then I can ask around and get some 
opinions on whether this is a cost worth bearing for greater performance.

Also, does this change improve the speed of "every frame appearance"? 
That has been a frustration for me. Users can turn off the frame but 
there's some important stuff there now (e.g. journal) so I think we need 
to make it work faster (especially make it go away faster).

BTW Its great to see some progress on the performance front. Certainly a 
concern for our users. Also great to see Andres in the loop. He is one 
of the best engineers I have seen who can bridge the sur and devel/sugar 
lists.

Thanks,

Greg S

Date: Thu, 4 Sep 2008 10:42:32 +0200
From: "Tomeu Vizoso" <tomeu at tomeuvizoso.net>
Subject: Re: [sugar] [PATCH] screenshots hurt
To: "Erik Garrison" <erik at laptop.org>
Cc: sugar at lists.laptop.org, Greg Smith <greg at laptop.org>
Message-ID:
	<242851610809040142o6e0a565au15439856e6704cdd at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

On Thu, Sep 4, 2008 at 7:29 AM, Erik Garrison <erik at laptop.org> wrote:
 > > Sugar Developers,
 > >
 > > In the field and amongst our own developers there have been numerous
 > > complaints about the performance of Sugar.  One simple thing we can do
 > > to improve user experience is to stop taking screenshots on every
 > > tabbing event, every activity focus change event, and every frame
 > > appearance event.
 > >
 > > The attached patch to Sugar (most recent git head, 48dd24c6e) does
 > > simply that.  Andr?s Ambrois and I have tested the changes in question
 > > on a machine running 656 and on a machine running 2263 (the most recent
 > > joyride I have available-- code in question is identical to the current
 > > sugar git head).  We noted a considerable improvement in the speed and
 > > consistency of activity switching performance.
 > >
 > > These qualitative results are consistent with prior user interface
 > > profiling tests by Riccardo Lucchese, which have established that
 > > screenshot functionality occupies just shy of 50% of CPU time during
 > > activity switching [1].
 > >
 > > Please apply the patch and test on a *REAL* machine.  Please comment on
 > > the effects.  Note that on recent joyride builds the appearance of the
 > > frame on every tabbing event makes it more difficult to notice the
 > > performance change.

The patch looks good in that it does what intends and doesn't seem to
have any unintended effect. About the convenience of totally
deactivating screenshots in the next release, I think it's a decision
that needs to be taken on non-technical grounds. Are we going to
better serve our users' interests by doing so? Is the improvement of
perceived performance worth the lost functionality? Greg, can you help
on this?

Note that I understand this as a temporary measure, for the next
release I think we should properly address this issue. I have just
added two tickets on this regard:

https://dev.laptop.org/ticket/8303
https://dev.laptop.org/ticket/8304

Thanks a lot for looking into this,

Tomeu