Hi Labbe,
Don did implement ThreadPerRenderSurface a while back, I haven't test
this yet, but it would seem to be the appropriate threading model for
you. There might be need to tweak osgProducer a little to avoid the
reset of the thread model that you highlight.
Robert.
On 10/16/06, Labbe, Mathieu <[EMAIL PROTECTED]> wrote:
Hi again,
Thanks for tips. The final implementation will work on 4 displays (2 video
cards (NVIDIA) with 2 displays each).
So, I don't really need two windows on each card. I can use 2 windows with 2
viewports… but I saw in osgProducer::OsgCameraGroup :
if (renderSurfaceSet.size()!=_cfg->getNumberOfCameras())
{
// camera's must be sharing a RenderSurface, so we need to
ensure that we're
// running single threaded, to avoid OpenGL threading issues.
_threadModel =
Producer::CameraGroup::SingleThreaded;
}
Is there a way to use 2 render surfaces with 2 cameras each, also
multi-threaded (I mean 1 thread running 2 cameras for each window)?
________________________________
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]
Sent: 16 octobre 2006 12:04
To: osg users
Subject: Re: [osg-users] Draw and SwapBuffers performance
Hi Mathieu,
For each graphics card you have basically one GPU than can only handle
rendering from one graphics context at one time, and switching between these
contexts will require flushes of all currently disptched commands and a
state switch on the GPU to switch between the contexts, this is going to be
expensive. Ideally you should have one thread, rendering to one context on
one graphics card.
Do you really need two windows on each card? Could you get away with one
window but two viewports?
If you really do need two seperate windows that the best solution would be
two have the rendering for each camera to be seriealized.
Producer/osgProducer doesn't support this model of threading though so you'd
have to manage it by hand.
Robert.
On 10/16/06, Labbe, Mathieu <[EMAIL PROTECTED]> wrote:
Hello,
I'm testing the performance of OSG 1.2 with 2 displays (2 video
cards (NVIDIA) with 1 display each and 2 CPUs dual core). I had strange
results so I need help to understand. (I tested it on an application like
OsgViewer). I used the stats option and some "printf()", I got these
numbers:
With 4 cameras with same view, 4 contexts (4 windows 640 / 512, two windows
on each display). At this point, I have 4 threads for the cameras:
FPS: 19.5
Update: 0.29 ms
Cull: 2.4 ms Draw: 40 ms GPU: 32 ms Swap Buffers: 2.5 ms
Cull: 1.9 ms Draw: 38 ms GPU: 34 ms Swap Buffers: 3.2 ms
Cull: 2.3 ms Draw: 38 ms GPU: 26 ms Swap Buffers: 3.9 ms
Cull: 1.9 ms Draw: 38 ms GPU: 26 ms Swap Buffers: 6.4 ms
Total: Cull: 2.4 ms Draw: 40 ms Swap Buffers: 6.4 ms =
20.49 Hz
With 4 cameras with same view, 1 context (1 window 2560 / 512, half of the
window on each display). At this point, I have 1 thread for the cameras:
FPS: 39.7
Update: 0.18 ms
Cull: 1.2 ms Draw: 5.4 ms GPU: 0.6 ms
Cull: 1.3 ms Draw: 3.5 ms GPU: 1.4 ms
Cull: 1.2 ms Draw: 3.5 ms GPU: 0.5 ms
Cull: 1.3 ms Draw: 3.5 ms GPU: 0.5 ms
Total: Cull: 5 ms Draw: 15.9 ms Swap Buffers: 4.3 ms = 39.7
Hz
Why drawing stage is ten times larger (for each camera) when the threads are
used?
I supposed that each camera calls glCallList() and for that, the threads
don't have access to GPUs simultaneously. I tried to force the drawing stage
to be sequential (I used a mutex around sh->draw( *this ) in
Producer::Camera). I obtained these results:
With 4 cameras with same view, 4 contexts (4 windows 640 / 512, two windows
on each display). At this point, I have 4 threads for the cameras:
FPS: 37
Update: 0.32 ms
Cull: 2.0 ms Draw: 3.7 ms GPU: 0.9 ms Swap Buffers: 7.5 ms
Cull: 2.3 ms Draw: 3.3 ms GPU: 5.1 ms Swap Buffers: 8.0 ms
Cull: 1.9 ms Draw: 3.3 ms GPU: 1.6 ms Swap Buffers: 7.5 ms
Cull: 2.4 ms Draw: 3.5 ms GPU: 1.5 ms Swap Buffers: 10.4 ms
Total: Cull: 2.4 ms Draw: 13.8 ms Swap Buffers: 10.4 ms = 37.6
Hz
Now I get better performance when the drawing stage is sequential
(?!?why?!?) but the Swap Buffers take almost the double times of the initial
configuration. I'm not very familiar with the SwapBuffers() function, so if
someone who wants to tell me how it works (to explain why SwapBuffers() time
are not always the same), it will be appreciated :)
Mathieu
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