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From: mouse@LARRY.MCRCIM.MCGILL.EDU
Newsgroups: comp.windows.x
Subject: Re:  GC: how many is too many?
Message-ID: <9012030453.AA18589@Larry.McRCIM.McGill.EDU>
Date: 3 Dec 90 04:53:08 GMT
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 33

> What is the maximum number of GC's that can be cached on X displays
> on the Sun workstations and the DECstations?

It depends on the server.  The MIT sample server does not cache the
things in hardware (all drawing is done by the main CPU scribbling on
the framebuffer), so the only limit is memory: each GC you create
corresponds to a structure allocated in dynamic memory by the server.
If the server *does* take advantage of specialized hardware, all bets
are off - it depends entirely on what the hardware can do and how the
server uses it, though it is unlikely that the overhead per GC will be
*less* than for the sample server.

> Is there an upper limit on the number of GC's that an X application
> should reasonably create?

More than one per drawing operation performed is probably excessive :-)

I wouldn't worry about it.  If the application creates more than about
a dozen I'd start wondering what's going on that it needs so many; if
you think you want more than ten or so you are probably going about
something the wrong way.  (I can't give any definite number because
there is no sharp line between "OK" and "too many".  This estimate of
about ten or fifteen as a point at which you should start wondering if
you're doing things wrong is just a feeling, not a Rule.)  This number
I'm referring to is the number of GCs you actually create, not the
number of conceptually different GCs.  (They're not the same thing
because many conceptually different GCs may be implemented identically,
or perhaps may be implemented as one GC which keeps getting changed.)

					der Mouse

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