Hi Mathias,
Yes, my apologies. Should have at least acknowledged your reply.. ATM all the
machines with the source files and data are off line and sitting on the shelf
while I work on the cockpit.
Hopefully, I can bring it all on line next month and power up the sim. Then
will be able to extract the relevant source and data for the warping. Also want
to confirm Stuart's comments related to running multiple machines.
Even if the random stuff is "deterministic" across machines if you start with
the same seed, I foresee a real need, perhaps even demand, for FlightGear to
live in a multi-machine federated system. Just consider what Nvidia has
accomplished with GPUs running as super computers.
Cheers
John
----- Original Message -----
From: "Mathias Fröhlich" <mathias.froehl...@gmx.net>
To: "FlightGear developers discussions"
<flightgear-devel@lists.sourceforge.net>
Sent: Tuesday, June 19, 2012 11:18:35 PM
Subject: Re: [Flightgear-devel] Slow frame rates
Hi,
On Sunday, June 17, 2012 13:00:15 castle...@comcast.net wrote:
> This email rekindled an idea from a while back. Last year while working on
> the 747 sim with multiple projectors and a quad core CPU I experimented
> with setting up three instances of fgfs - one for each cpu, graphics card,
> and projector. The improvement in the frame rate was quite dramatic; from
> around 20-22 fps to over 55 fps for each instance. The down side was that
> all the dynamic features (3d clouds, AI objects, random stuff, etc) all ran
> in their own graphics context. so while all the static scenery sync'd
> across the projectors, the dynamic objects "ended" at the display
> boundaries.
>
> Multi-core machines have been around for some time now. Perhaps it is time
> to think beyond running Flighgear as a monolithic process in a single CPU
> configuration.
>
> It is my understanding that all three platforms ( MS, Mac, Linux) support
> some form of shared memory IPCs. I use shared memory in the 737/747 cockpit
> software to great advantage with a global section for all common data and
> sharing data between the Captian, FO, and MCDUs processes.
>
> In Linux creating a shared memory segment is simple and straight forward.
> The "master fgfs" would create the shared segment and compute the graphical
> objects, in this case clouds and AI, and the "fgfs slaves" would simply
> access the shared segment for the data required to create their visual
> scene.
>
> Hopefully, I'll have some time in the fall to pursue this idea further. In
> the mean time, the floor is open to anyone who would like to comment or
> pursue this idea on their own.
Well, that's about what I am about to do with the HLA stuff.
The nice thing is that the ipc is hidden behind something that is also able to
distribute this across multiple machines. A local network connect is mostly
sufficient. But doing the same by an infniband connect is possible too.
Experimenting with shared memory did not bring notable improovements over a
system local network connect. At least not on linux...
In any case I think this could be fast enough to do this stuff.
Also this stuff is based on a standard that is probably enables us to be a
little more connective in the end. At least this is a slight hope from me.
John, by this way, I did send you some mails regarding the unwrapping, but did
never get an answer - did you recieve them?
Mathias
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