[visionegg] Re: time and OS es

Christoph Lehmann wrote: 
Christophe
just a short remark concerning latencies under linux, for visual stimulation. As
far as I remember when I used visionegg, I got latencies BUT only if the
hardware OpenGL acceleration was not enabled. After enabling this the timing was
really extremely precise (<2ms, I think).

I observed something similar with stimulus software I wrote myself using the SDL-library under Linux. When I enabled DGA and used the interrupt mechanism provided by SDL, the timing was exact <1ms, even on an old 450MHz Pentium II machine. I simply logged the timing of all events during the experiment to check this - no glitches at all.

The only drawback I found there was that there is no easy way to control the screen refresh exactly (i.e. via a VSYNC signal) - has anybody got any clues how to achieve this?

The idea of a stripped down distribution is a good one (I usually only disable power management).
Once latency problems are solved, a project that would get me excited would aim at creating a Linux-Live CD for Psychophysics (a la Knoppix).

Very good idea - I will probably do some more psychophysics later this year, so I may be able to contribute.

Best wishes (and sorry for yet another off-topic),
Matthias

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