Hi Costa,I have a question!
What version of OpenCL version does the Brlcad applications renders on?
If my computer has a different version does it matter or it get supported?
I installed OpenCL 2.0 (Version) including; All the CL/.. header files. Because
currently my computer is;
Windows 10, and comes with OPENCL 2.0.4.0 drivers.
Do I have to ADD any Path to the Environment and/or to IDE to point to the
OpenCL Library/bin?
Since Windows 10 comes with OpenCL 2.0.4.0 drivers, I guess this is compatible
with an AMD NVIDIA card and I should not have to worry about the Nvidia card
version.
Do I have to set OpenCL Environment Variable in the computer system to EQUAL
the number of Processors?
How many Platforms are there in GPU or computer? is that suppose to be equal to
the number of processors?
And can you also explain more about the boolean Evaluation and the Constructive
Solid Geometry(CSG) operations. And what needs to be done here?
Thanks.
From,
Benson Chepkwony
On Sunday, March 13, 2016 4:53 PM, Vasco Alexandre da Silva Costa
<vasco.co...@gmail.com> wrote:
On Sun, Mar 13, 2016 at 2:23 AM, benson chepkwony <bchepk...@att.net> wrote:
HI Costa,
I have performed mid-level programming on concurrency, threading and
parallelism. With pThreads, OpenMP and Java threading. However I am new to
OpenCL.
OpenCL requires similar threading techniques if I am not wrong.
Not really. I guess you did not read the article about SIMT I linked to.
And I was going to ask you, if tuning the application or C/C++ code into a
parallel code is important? by that, I mean conducting; optimization,
eliminating dependency(i.e True, Anti, ..), Loops transformation, Data
transformation, Aliasing issues, Anti-aliasing etc.
Is there a specific Target area you should identify in your code? that needs
to be implemented for OpenCL platform. Such as an Algorithm, Loops, functions,
input/output readers etc. And how do you determine this particular Target area?
I am not going to teach you how to program in OpenCL. Or the differences
between C and OpenCL. It's expected that you learn that by yourself. I even
provided you with some links to resources on the topic which you seem to have
ignored...
I have been familiarizing myself with OpenCL and I have a few questions.
Are we targeting the GPU on this project?
The targets are GPUs and multi-core CPUs. So yes.
Are we therefore conducting GPU programming with OpenCL?
I was wondering if this is the OpenCL procedure, that we should follow on this
project.
- There a two kinds of OpenCL process:
Kernel Code program
Host Code program
- OpenCL Host Program Procedure:
Define platform and Queues
Define Memory objects
Create the program
Build the program
Create and setup kernel
Execute the kernel
Read results back to the host
So here our biggest task is identifying routines, functions, algorithms and
loops on Brl-cad Primitives i.e ETO that needs to be implemented and modified
to performs its work/task under OpenCL Platform? Then identifying OpenCL Memory
Objects, Work-Items, etc.
How do you identify these primitives`s functions and algorithms?
That's supposed to be your job... i.e. read the BRL-CAD code and understand it.
I'm only here to provide you with pointers and guide you along the way.
And for this project we are looking for Work-Items and Work-Groups in
primitives c codes that can be computed concurrently under OpenCL GPU Platform.
Thanks.
From,
Benson Chepkwony
On 3/10/2016 12:10 PM, Vasco Alexandre da Silva Costa wrote:
On Thu, Mar 10, 2016 at 3:51 AM, benson chepkwony <bchepk...@att.net> wrote:
Hi Costa,
Are we suppose to be "Porting" these primitives the(RHC, ARB4, DSP, EXTRUDE
etc) from its current rendering structure to OpenCL?
Is there any compatible issues with moving these primitives to OpenCL?
In order to "Port" these pimitives are we going to just "read in" their
extensions to OpenCL?
I think I already gave you enough info so you can work on a patch. Rome
wasn't built on a day. You need to focus on an achievable task. Focus on one
primitive for now. I suggested one.
OpenCL is not C compatible so yes there will be issues porting the code over.
The syntax is C like but OpenCL is a language designed for parallel programming
in a SIMT fashion. I you want to know more about OpenCL you can go to
www.khronos.org. They have online an overview reference card of the language so
people already familiar with C and graphics programming can get a quick start:
https://www.khronos.org/files/opencl-1-2-quick-reference-card.pdf.
I was also looking at your "Milestone" on your logs and you wanted to
implement HLBVH acceleration structure with the Bounding Volume Hierarchy to
traverse the ray packets. Did you actually implemented this acceleration
structure?
The HLBVH is in BRL-CAD SVN trunk. It is currently built on the CPU as a
pre-processing step, sent to the GPU, then the GPU traverses it during the
rendering passes.
I wrote a Proposal too last year for GSoC that specifically targeted the Ray
Packets coherency traversal as acceleration structures for performance
improvement.
Ray packets is a technique which is commonly used with fixed width SIMD
architectures like x86-64 SSE or AVX. In a SIMT model the lane size can vary.
In practice this is what also happens with x86 hence the multiple instruction
standards to increase the lane size. 128-bit, 256-bit, eventually 512-bit, etc.
This article explains the concept differences nicely:
http://yosefk.com/blog/simd-simt-smt-parallelism-in-nvidia-gpus.html
I was also going to ask you about the OpenMP multithreading compiler support.
How does this work?
It doesn't. It was a throw away prototype used in the process of producing an
OpenCL final prototype.
which part of performance improvement were you targeting with the OpenMP
multithreading?
How does OpenCL platform working i.e do you have to install the OpenCL in your
computer in order to run the current Ray Tracing? and is OpenCL going to be
shipped with Brl-cad software?
This is a rather basic question to ask... The BRL-CAD OpenCL rendering mode
is optional and is to be activated only if people have OpenCL on their
computers. Rather like OpenGL it is either installed by the user or comes with
the OS install. The implementation may be in a GPU driver (AMD, NVIDIA) or can
be downloaded from one of the multi-core x86 CPU vendors (AMD, Intel).
If you do not have prior OpenCL or CUDA programming experience you are
probably better off choosing some other project to work on right now. The
OpenCL language syntax itself is not that hard to learn for someone who knows
ANSI C well, but the parallel programming concepts can be challenging to master
and the development environment tools are still in their infancy.
Thanks.
From,
Benson Chepkwony
On 3/9/2016 4:05 PM, Vasco Alexandre da Silva Costa wrote:
On Wed, Mar 9, 2016 at 4:52 AM, benson chepkwony <bchepk...@att.net> wrote:
Hi Costa,
I just went through your logs. And its seems on your patch, you modified Three
files; EHY, ELL and ARB8. And in specific you worked on Elliptical Hyperboloid,
Ellipsoid and Polyhedron Algorithms.
Actually I worked on ARB8, ARS, BOT, EHY, ELL, SPH, REC, TOR, TGC.
Is there any work left to do on these Algorithms? or should we continued
optimizing these 'librt/primitives' files that you worked on?
Each of the primitives has a .cl and a .c file with the primitive
implementation in OpenCL/C. IIRC the only primitive, of those I worked on,
which is not feature complete is BOT (Bag Of Triangles). e.g. BOT in OpenCL/C
does not have plate mode support yet. You could work on that or on implementing
some other relevant primitive like ETO. ETO is a quartic kinda like TOR and
the quartic solver has been ported to OpenCL already.
You take a look at the BRL-CAD primitives here (I mentioned this before in
this list):
http://brlcad.org/w/images/5/52/MGED_Quick_Reference_Card.pdf
You can submit your work as a patch in unified diff format (e.g. 'diff
-Nurd').
Did you just modified the Algorithms on this specific files or is this more
than just Algorithm modification?
I am sure you did the profiling in the initial stages. And this should be our
starting point but since you have done it, do we have to profile again? I am
sure you had so many files to work with under 'librt/primitives'.
You should do accuracy tests for each primitive you implement similar to what
I did in Week 10:
http://brlcad.org/wiki/User:Vasco.costa/GSoC15/logs#Weeks_9-10_:_20_Jul-26_Jul.2C_27_Jul-2_Aug
i.e. a pixdiff between the existing ANSI C primitive implementation and the
OpenCL implementation.
At this point performance profiling (e.g. timing tests) should be done with
more complex models than a single primitive. When I started out I had to
reimplement the whole rendering pipeline so some of those tests are more to
test buffer writing performance than actual ray tracing algorithm performance.
Regards,
-Vasco Costa
From,
Benson Chepkwony
On 3/8/2016 8:55 PM, Vasco Alexandre da Silva Costa wrote:
On Tue, Mar 8, 2016 at 10:35 PM, benson chepkwony <bchepk...@att.net> wrote:
Hay Costa,
I am interested with this project titled "Ray tracing performance, coherent
boolean evaluation". I understand you worked on this project last year, that
is good. However, I was wondering if you could further elaborate what you did
with the coherency and which area did your research reside in?
I am not sure about this but since it is a continuation of your work, I am
not sure if we have to apply and use the coherency Techniques that you applied?
How is the Ray Tracing working out at this point? and what area need to be
further research? Do we need to understand your code fully to work on this
project?
What files in the binary is this project located?
Welcome aboard.
You can see the Blog of my activities last year if you are interested in what
I actually did.
http://brlcad.org/wiki/User:Vasco.costa/GSoC15/logs
Basically what I did was a port of the basic ray tracing pipeline to an
OpenCL GPU environment. This includes numerous supported primitives. What it
doesn't support is boolean evaluation i.e. CSG (Constructive Solid Geometry)
operations. Anyone interested in working on the OpenCL ray tracer should get
familiar with the BRL-CAD code e.g. by making a patch to add OpenCL
acceleration to an existing primitive like 'eto'.
Afterwards we can look at how the standard BRL-CAD rt pipeline does CSG ops
and how to achieve this in a GPU amenable fashion. For this I will you give
you pointers for where to start reading the code. But be prepared for some
rough sailing. I have a rough outline of how this can be done but you guys
need to get a feel for it and I want your own opinion on how to do it. I
already have mine. :-)
Read all the e-mail correspondence I have had with Param Hanji
<param.catchch...@gmail.com> in this list. Since both of you guys seem to be
interested in the same subject:
https://sourceforge.net/p/brlcad/mailman/brlcad-devel/
There is enough work here for two people but we need to figure out what your
strengths are, get you guys to understand the problems, so you can figure out
which approach or which part you want to work on. What I do not know is how is
the workshare allocation for GSoC this year.
All the best,
-Vasco Costa
Thank you.
From,
Benson Chepkwony
--
Vasco Alexandre da Silva Costa
PhD in Computer Engineering (Computer Graphics)
Instituto Superior Técnico/University of Lisbon, Portugal
--
Vasco Alexandre da Silva Costa
PhD in Computer Engineering (Computer Graphics)
Instituto Superior Técnico/University of Lisbon, Portugal
--
Vasco Alexandre da Silva Costa
PhD in Computer Engineering (Computer Graphics)
Instituto Superior Técnico/University of Lisbon, Portugal
--
Vasco Alexandre da Silva Costa
PhD in Computer Engineering (Computer Graphics)
Instituto Superior Técnico/University of Lisbon, Portugal
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