Re: [Xpert] Re: [rtl] Re: Virge DX and accel. introduced latency? (was Re: [Xpert]XFree86in realtime applications)

[Erwin Rol]

A quick last check on this sunday evening resulted in the following:

x11perf -copyplane500
caused a CPU usages of about 100% on my TB 800 but latency of the
realtime task 
stayed around 15usec +/- 3usec

a "cat /dev/mem" in a gnome terminal caused a latency 
of about 12usec +/- 3usec.

Tomorow it is switching to X 4 again :-) 

- Erwin


Mark Vojkovich wrote:
> 
> On Sun, 26 Nov 2000, Erwin Rol wrote:
> 
> > What would be a good test programm to really push the accelerator to the
> > max, and
> > in all possible accelerations ?
> 
>   Retries seem to occur most easily when full blits and color
> expansion are used together.  Text scrolling in an xterm would
> do this nicely.  Heavy color expansion usage would be induced with
> 
>   x11perf -copyplane500
> 
>   This results in alot of data tranfered across the bus.  However,
> it never really fills up the fifo because the bus is the bottleneck
> and the engine can usually go through the data as fast as you can
> send it.  So it's the combination of color expansion with expensive
> blits to clog up the pipeline that make the retries occur.  Cat
> large files in a loop in an xterm and you will be in retry city.
> 
>                                 Mark.
> 
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