[sugar] Slowness (was Re: notes from the field - Mongolia)

[Erik Garrison]

Hey Elana,

One thing which you can do to improve activity switching performance is
to run xcompmgr (X composite manager).  This prevents the activities
from burning CPU time redrawing themselves every time they are switched
to by persistently caching the video memory used by each window.  The
result is notably improved activity switching performance.  But it does
so at the cost of memory, as each window open consumes about 2MiB more
RAM.

One notable problem with this approach is that doing so requires more
memory and thus, if the user runs a lot (in testing >4 or 5) of
applications the system will become quite slow.  It would be helpful to
know if the activity switching performance boost provided by wholesale
use of X composite is outweighed by the potential out-of-memory
situations.  How many activities are kids typically using?  Would they
prefer a system which had much better window manager navigation
performance at the cost of not being able to run as many activities?

What version of our software (what build) is being used for the tests?
Scott suggests that you are running 649.  I have tested the following
procedure to run xcompmgr on that build:

To install xcompmgr in the Terminal:

    su
    yum install xcompmgr
    # indicate 'y' when asked

To run, again in the terminal:

    xcompmgr

You won't be able to close the terminal while running the tests.

You should notice an improvement in switching performance and frame
redraw.  The residual latency in switching appears to be caused by
activity autosaving, but my testing experience with 649 is not sufficent
to pass judgement on this issue.

Erik

On Thu, Oct 09, 2008 at 01:22:21PM -0400, elana langer wrote:
> in addition to boot and activity load time the time it takes to switch
> between applications is also a little frustrating - especially for
> kids who have worked on faster computers.
> 
> I am in Mongolia for the next few weeks. There are several schools in
> the city that have computers so if you want any testing done (like the
> reaction to the boot time with 8.2) just let me know. If you send me a
> list of "dream field feedback" or something I can try to make that all
> happen.
> 
> On Thu, Oct 9, 2008 at 4:59 AM, Tomeu Vizoso <tomeu at tomeuvizoso.net> wrote:
> > Hi Elana,
> >
> > you have brought a very needed point of view to this list. Let me try
> > to start the process of translating your experience to actionable
> > items.
> >
> > On Mon, Oct 6, 2008 at 5:20 PM, elana langer <elana.langer at gmail.com> wrote:
> >>
> >> 1) Computers are slow - So I was in a Ger in the west part of Mongolia
> >> and I thought I would show the computer to the family that was hosting
> >> me. The husband, wife and 8 year old child huddled around the computer
> >> and pressed the on button. Instead of being delighted by the computer
> >> they waited, and waited for the computer to load. I asked them in
> >> broken monoglian to be patient but once the computer loaded they
> >> wanted to open an application and again more waiting. The 8 year old
> >> lost interest as did the mom and only the man of the house stuck
> >> around to try things.
> >> This is not a unique experience. This is a culture that lives close to
> >> the land. Action- reaction. No one is used to "waiting" for an
> >> computer to load or a bagel to toast for that matter. (of course
> >> cooking takes time but they can watch as it changes form not just an
> >> unmoving screen)
> >>
> >> In the city the experience is worse. Kids used to PCs quickly grow
> >> impatient and leave the XO to find other faster computers.
> >
> > First, I would like to note that you are talking about perceived
> > slowness, not the absolute time that takes to do anything. So to solve
> > the issues you mentioned, we need to give a sense to the user that
> > something is happening and, when possible, how much time it will take
> > to finish, in case reducing the time it takes is too expensive
> > resource-wise.
> >
> > Second, you talk about boot time and activity launch time. Is there
> > any other action in the laptop that causes problems because of its
> > slowness?
> >
> > And third, both booting and activity launching performance are known
> > problems and some improvements already happened in the last stable
> > release, 8.2.0. Do you think you could do some experiments with that
> > release and see if things have improved and if so, how much?
> >
> > Thanks,
> >
> > Tomeu
> >
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