Hello,
This may be relevant:
Memory Speed, QPI and Multicore
http://www.masm32.com/board/index.php?PHPSESSID=afe5222fb85c769a44da28f1eb5d4b82&topic=17296.0
Peter
----- Original Message -----
From: "Jason Daly" <jd...@ist.ucf.edu>
To: "OpenSceneGraph Users" <osg-users@lists.openscenegraph.org>
Sent: Thursday, January 26, 2012 6:49 PM
Subject: Re: [osg-users] Request for input
Hi, JP,
On 01/26/2012 01:53 AM, J.P. Delport wrote:
very interesting and thorough investigation. I can't really add anything
and unfortunately don't have representative hardware to test on. It
would be interesting to see if different bus configs
(motherboards/chipsets) make any difference.
The target hardware is a dual Xeon system with a 5400 chipset (the last
chipset with a FSB) and a pair of QuadroPlex D2's. I've been working on
an Alienware desktop with an X58 chipset and two GeForce 260's. One would
expect that the X58 with its QPI interconnect would succumb to bus
contention later than the 5400 (the specs say so, at least), but on the
largest data set, it appears that the X58 is still having the scaling
problem, while on the workstation, the bottleneck has moved elsewhere.
I also would not rule out
the NVidia driver doing silly things. I remember once looking at some of
the glue code for the binary blob and seeing TLB flushes that caused a
Xenomai kernel to fail ito timing in interesting ways.
Have you tried OProfile to get some idea of time spent in the driver?
I'm not familiar with OProfile. I'll take a look.
Thanks for the reply!
--"J"
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