Re: [Caml-list] f#/mono vs ocaml runtime system - open gl animation screen tearing.

["Török Edwin" <edwintorok@gmail.com>]

On 04/26/2011 10:15 PM, Peter Ronnquist wrote:
> Hi all,
> 
> I have been experimenting with f# and mono on debian linux and
> compared it with ocaml.
> I am interested in visual presentations for example games and in my
> tests f# + mono + opentk was able to make completely smooth animations
> using opengl (opentk) on debian 6.0 (squeeze).
> 
> Ocaml + lablgl gives "stutters" in the animation within the period of
> a couple of seconds. The animation runs smooth for a couple of seconds
> and then the animation update is disturbed with the result that the
> image is "teared". The tearing lasts only for a fraction of second but
> is visible for a trained eye.

Did you try to synchronize to VSYNC?
Also which OpenGL drivers are you using, some older versions of the
Intel drivers used to have quite significant tearing even with 2D
animations/video.

> 
> I suspected that the GC could be a cause for this and I tried to
> manipulate the GC settings but I could not get a completely smooth
> animation for a longer period of time.
> 
> This is completely acceptable for many applications but for making a
> game or for the meticulous graphical applicaton user it is not ideal.
> 
> My thought is that maybe f#/mono unboxes more values than ocaml and in
> this way the GC doesn't need to work as hard?

Try 'latencytop', and 'perf record/perf report' to see where time is spent.

> 
> My question really is if you think it is worthwhile to investigate the
> runtime system for mono and compare it with the runtime system for
> ocaml to locate the differences that might influence the animation and
> then even update the ocaml runtime system to use a similar strategy
> as the f# runtime system?

Do you have a simple testcase? (OCaml code vs Mono code that easily
reproduces the issue?)

Best regards,
--Edwin