🚀 go-pugleaf

In article <1992Oct30.235141.4139@kakwa.ucs.ualberta.ca> Gary Ritchie writes:
>What I have done is to turn off color by default in ALL applications with:
>      dwrite -g NXWindowDepthLimit TwoBitGray
>...you can reenable color selectively, ie:
>      dwrite GoldDigger NXWindowDepthLimit TwelveBitRGB

What a fine choice of an app to run in color. 8-)

>Have others tried this technique before?  Is my machine really going  
>faster, or am I just light-headed from hunger late on a Friday afternoon?

The window server uses lazy promotion to assure that windows remain skinny
until they need to draw some color that cannot be represented in the current
depth. All windows start life out as 2-bit windows, the moment you draw
one of the non-standard 4 grays, they get deeper. This promotion
continues upto the time the windows reach their depth limit.

On a 2-bit machine, all windows are depth-limited to 2-bits (by default). Thus
windows will never get deeper than 2 bits. On a NSC, they are depth limited
to 12 bits. Thus, by doing the TwoBitGray dwrite on a NSC, you are simply
making all windows remain at 2 bits.

This operation will save memory; backing stores of would-be color windows
now occupy 8 times less memory. It can also speed up drawing, depending on the
type of drawing operations. However, it does slow down the flush from the 
backing  store to the screen in some cases; for instance, flushing an 8-bit 
window to a 12-bit screen isn't too zippy. Flushing a 2-bit window to a 12-bit
screen is pretty quick, so it is conceivable that your machine might seem a 
bit faster with a 2-bit window depth limit. The reduced swapping probably
helps as well, when switching between apps.

One final note... Flushing 2-bit windows with alpha to a 12-bit screen is
rather slow, and I believe this is what causes Frame to run real slow
on a NSC when the window depths are limited. If you don't limit the
depth, Frame's windows become 12-bits (with alpha), and in that case the
flush is much faster.

Ali, Ali_Ozer@NeXT.com