[Flightgear-devel] UIUC FDM

2006-04-08 Thread Pigeon

In the progress of testing the FG live cd (under qemu), I discovered
a rather interesting behavior of the UIUC FDM.

(My) qemu by default ram size to be 128mb. When I was trying to run
fgfs, it gave me an exception of std::bad_alloc and then terminated.
After having some hints from Melchior on what this could mean, followed
by a run under gdb, it pointed me to src/FDM/UIUCModel/uiuc_wrapper.cpp
line 120, which is simply a global:

AIRCRAFT *aircraft_ = new AIRCRAFT;


Then we check the size of the AIRCRAFT struct, and it turns out to
be about 117mb.


I probably don't know enough about UIUC's or in fact any FDMs'
internals and so I can't say whether this is a lot of memory for a FDM
or not. But having 117mb of memory allocated (or committed) at startup
(this is even before main(), btw), regardless of what aircraft/FDM is
being used, is probably not a good thing. Codewise, this struct is
rather big...

Anyway, I imagine someone who knows a bit more about UICI's code
could make it new-ing the struct only when it's actually used?


Pigeon.



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Re: [Flightgear-devel] UIUC FDM

2006-04-08 Thread Vassilii Khachaturov
 I probably don't know enough about UIUC's or in fact any FDMs'
 internals and so I can't say whether this is a lot of memory for a FDM
 or not. But having 117mb of memory allocated (or committed) at startup
 (this is even before main(), btw), regardless of what aircraft/FDM is
 being used, is probably not a good thing. Codewise, this struct is
 rather big...

It's possible to disable the UIUC and other esoteric FDMs entirely at
the configure stage, IIRC.

V.



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