Messages in this thread | | | Date | Sat, 02 Jun 2001 17:42:27 -0400 | From | Jeff Garzik <> | Subject | Re: Reading from /dev/fb0 very slow? |
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Pavel Machek wrote: > > Hi! > > I did some benchmarks, and my framebuffer is *way* faster when writing > than when reading: > > root@bug:/home/pavel# time cat /tmp/test > /dev/fb0 > 0.01user 0.08system 0.09 (0m0.097s) elapsed 93.13%CPU > root@bug:/home/pavel# time cat /dev/fb0 > /dev/null > 0.00user 0.62system 0.62 (0m0.620s) elapsed 99.93%CPU > root@bug:/home/pavel# > > That is 6 times slower! This is also very visible in X, where moving > regions is expensive, while just drawing regions is fast. For example > gnome-terminal is *way* faster *with* transparent background option. > > Any idea why such assymetry? [This is toshiba 4030cdt with vesafb and > 2.4.5]
Do you have write combining enabled?
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