Re: Snappy GUI response

On Thu, Jul 03, 2003 at 01:34:04PM -0700, David Jeske wrote: 
> IMO, a bigger contributing factor is that the X design does not have
> application performance as its number one objective,

Personally, I think the biggest contributing factor is that not enough
people run and publish profiles and analysis of real-world specific UI
interactions and their performance. In part this is due to lack of
good measurement tools, but there are some useful tools out there.

The results of a good profile are almost always surprising and almost
always show places that are quite possible to improve.

Vague general statements about X or the kernel or toolkits don't get
us anywhere, though. There are easily 10 million lines of code
involved in the whole stack of software leading to rendering a web
page; guessing which lines are important is silly.

We can give you solid fact-based info on which bits of GTK+ tend to
show up in profiles, but I don't know that we have such info for the
system as a whole.

It's very important to focus on specific interactions, such as
"opening the start menu" or "launching mozilla" or "resizing opaquely"
rather than trying to talk about "overall snappiness" as well.

An interesting effort might be to carefully document every layer of
code and what it does going from clicking the start menu button to the
menu coming up - documenting the path through the toolkit, Xlib, X
server, kernel, etc. and all the process switches and abstraction
layers you go through. If you could do the same on Windows (hard
without source code!), you might be able to create an interesting
comparison. If you did this for a number of different interactions, it
might be even more interesting.

It's also important to keep in mind that effects such as flicker and
"tricks" such as progress indication can create an illusion of speed
or slowness that isn't really accurate. This illusion can even vary by
person; some people seem to interpret flicker as "slow to redraw" and
some seem to interpret it as "rapidly doing lots of work"

Havoc