On Thu, Nov 07, 2002 at 02:08:47AM +0000, Pigeon wrote: > From README.cirrus out of XF86 4.2: > >On older chips, the use of a higher dot clock frequencies has a negative > >effect on the performance of graphics operations, especially BitBlt, when > >little video memory bandwidth is left for drawing (the amount is displayed > >during start-up for 542x/3x/46/6x chips). For the 542x/3x chips, with > >default MCLK setting (0x1c) and a 32-bit memory interface, performance with a > >65 MHz dot clock can be half of that with a dot clock of 25 MHz. So if you > >are short on memory bandwidth and experience blitting slowness, try using the > >lowest dot clock that is acceptable; for example, on a 14" or 15" screen > >800x600 with high refresh (50 MHz dot clock) is not so bad, with a large vir- > >tual screen. > > I guess the "natural" resolution & speed is that which gives the > "best" compromise between refresh rate and drawing performance. It's > probably that which Windoze calls the "optimal" rate.
I'd say this is fairly moot once you're getting into AGP 2x video cards with hundreds of MIPS of on-board CPU with dozens of megabytes of extremely fast RAM :) -rob
msg11532/pgp00000.pgp
Description: PGP signature
