Messages in this thread | | | Subject | Re: Reading from /dev/fb0 very slow? | Date | Sat, 2 Jun 2001 23:03:24 +0100 (BST) | From | Alan Cox <> |
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> I did some benchmarks, and my framebuffer is *way* faster when writing > than when reading:
That is quite normal.
> 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]
Writes to a PCI device can be queued or posted. Reads from a PCI device for obvious reasons have to stall the CPU until the data returns.
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