Hi,
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.
Regards
John W.
----- Original Message -----
From: "Catherine James" <catherine.ja...@att.net>
To: flightgear-devel@lists.sourceforge.net
Sent: Friday, June 15, 2012 10:02:34 PM
Subject: [Flightgear-devel] Slow frame rates
Additional finding: if you do a File --> Reset immediately after startup, the
slow 1 - 2 fps problem goes away immediately and frame rates stay high
thereafter.
Something seems to be getting initialized either when breaking ground during
takeoff or in a File --> Reset that is not getting initialized on initial
startup.
Cathy
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