[simspark-devel] Fwd: Fwd: multi-threaded ODE

[Hedayat V. <hed...@gm...>]

Hi,
This is the last email I found from Hesham, with his last
implementation. It might be helpful regarding the recent discussions. I
hope it gets the attention it deserves. :)

Good luck,
Hedayat

-------- Original Message --------
Subject: 	Fwd: multi-threaded ODE
Date: 	Mon, 16 Jun 2008 07:58:04 +0200
From: 	H.Ebrahimi <hes...@gm...>
To: 	Sahar Asadi <sah...@gm...>
CC: 	Joschka Boedecker <jos...@am...>, Yuan
Xu <xy...@ya...>, Feng Xue <hen...@ma...>, Hedayat
Vatankhah <hed...@ai...>




Hello Sahar,
(cc Joschka, Yuan, Feng and Hedayat)

I forgot to mention in scenserver.cpp on line 47 you see:
tbb::task_scheduler_init tbb_sched;
Sometimes on some machines, it's better to set the number of threads to
get the best performance. But in the code I sent you TBB sets the number
of threads automatically. On my laptop I get a very good result with 5
threads:
tbb::task_scheduler_init tbb_sched(5);
But with the latest version of TBB (released in June 2008), I got a very
good result without setting the number of threads. Apparently this
feature is improved in this version. So if you find time, it would be
great to test with different number of threads and compare the result.

Probably next weekend I can send you a version that doesn't need to
modify the server code. But I'm not sure if we get the same performance.

I forwarded this email since I'd forgotten to send it to Feng and Hedayat.

Best,
Hesham

---------- Forwarded message ----------
From: *H. Ebrahimi* <hes...@gm...
<mailto:hes...@gm...>>
Date: 2008/6/15
Subject: Re: Agent Type discussion and rules
To: Sahar Asadi <sah...@gm... <mailto:sah...@gm...>>
Cc: Joschka Boedecker <jos...@am...
<mailto:jos...@am...>>, Yuan Xu
<xy...@ya... <mailto:xy...@ya...>>



Hi Sahar,

2008/6/15 Sahar Asadi <sah...@gm... <mailto:sah...@gm...>>:

    @Hesham and Joschka: I am still waiting for source files to test
    with ODE changes


Sorry, last week I was away, couldn't work on this. I didn't manage to
compile the server with gcc 4.3, so had to install gcc 4.2. Probably
until next weekend I cant find time to prepare a patch, so if you don't
mind I send you the files and some small modification that should be done.

To have a clue of the speedup the multi-threaded version of ODE gives, I
use rdtsc to see the time each 100 ODE steps take (sceneserver.cpp
prints this number). On my laptop for 3 agents, with multi-threaded ODE
I get less than 1E7 and with original ODE I get around 1.6E7. But I
expect if we run the agents on other machines, we get even more speedup.
So sceneserver.cpp is the only file of the server I've modified. But
please modify Makefile in /lib/oxygen/ and add -ltbb -lpthread to:
liboxygen_debug_la_LIBADD = -ltbb -lpthread -lode ${spades_libs}
Since it will be linked with the static ODE library, if you want to link
with another version of ODE, need to link oxygen again. And please make
sure the release version of TBB is used. When you compile TBB, it gives
the debug and release versions. And the debug version is around 10 times
slower.

I've also attached all the source files of ODE in /ode/src/, please
replace the original ones with them. And also please add -ltbb -lpthread
to Makefile of ODE:
LIBS =  -lstdc++ -lm -lpthread -ltbb -ltbbmalloc -lrt
if you want to compile the tests and other directories in ODE, you may
need to modify their Makefiles as well.

Please let me know if you see any problems with compiling this. By the
way, please set the flag of "setAutoDisableFlag(true)" to false, in
spark.rb. In the tests I ran, in a few of them after running and
connecting the second agent, the server crashed. Please let me know if
you see this, in the previous versions of the server with multi-threaded
ODE I hadn't seen this.

Best,
Hesham