Re: Re: how to write snappy benchmark?

On Sun, Jul 06, 2003 at 01:27:38PM -0400, Havoc Pennington wrote:
| ...
| If you set the background pixmap to exactly the current contents of a
| window, you could avoid flashing, which is what we were discussing a
| bit. However, there is a memory cost (you have a large pixmap the size
| of every window).

There's at least one similar approach worth considering --
double-buffering using a single back buffer for the entire screen, with
synchronized buffer-swap during vertical retrace.  This avoids flashing*
and places a low upper bound on the amount of extra memory required.

I've used systems liked this.  They're quite effective, especially given
the drawing rates of modern desktop hardware.

Allen

* Assuming the apps are capable of redrawing quickly enough to maintain
interactivity, and the scheduler gives them time to do so.  It's a good
assumption for most apps and the past few generations of hardware.  For
fallback, a swap timeout on the order of two frame times is necessary,
and apps that miss the timeout may flash.

GLX extensions for swap control already exist and might be useful in the
2D world if toolkit developers wanted to give this sort of thing a try.