A while ago macresearch.com stopped from existing, as David Gohara pulled the plug. Luckily the sources of a very nice tutorial were not lost, and David gave us permission to share his material.

Even if you don’t have a MAC, then these almost 5 year old materials are very helpful to understand the basics (and more) of OpenCL.

We also have the sources (chapter 4, chapter 6) and the collection of corresponding PDFs for you. All material is copyright David Gahora. If you like his style, also check out his podcasts.

Introduction to OpenCL

OpenCL fundamentals

Building an OpenCL Project

Memory layout and Access

Questions and Answers

Shared Memory Kernel Optimisation

Did you like it? Do you have improvements on the code? Want us to share more material? Let us know in the comments, or contact us directly.

Want to learn more? Look in our knowledge base, or follow one of our  trainings.

We have some embedded devices here, which badly need attention. Some have gotten some private time on the bench, but we did not share anything on the blog yet with our readers. We simply need some extra hands to do this. Because it’s actually cool to do, but admittedly a bit boring when doing several devices, it was the perfect job for an intern. Besides the benchmarking, we have some other Linux-related projects for you. You’ll get an average payment for an internship in the Netherlands (in Dutch: “stagevergoeding”), lunch, a desk and a bunch of devices (aka toys-for-techies).

Like more companies in the Netherlands, we don’t care about how you where born, but who you are as a person. We expect from you that you…

• know everything about Linux administration, from servers to embedded devices.
• know how to setup a benchmark.
• document all what you do, not only the results.
• speak and write Dutch and English.
• have great humor! (Even if you’re the only one who laughs at your jokes).
• study in the EU, or can arrange the paperwork to get to the EU yourself.
• have a place to live/crash in or nearby Amsterdam, or don’t mind the daily travelling. You cannot sleep in the office.

Together with your educational institute we’ll discuss the exact learning goals of the internship, and make a plan for a period of 3 to 6 months.

If you are interested, send a mail to jobs@streamhpc.com. If you know somebody who would be interested, please tell that person that we’re waiting for him/her! Also tips&tricks on finding the right person are very welcome.

The research lab LaSEEB (Lisboa, Portugal) is active in the areas of Biomedical Engineering, Computational Intelligence and Evolutionary Systems. They create software using OpenCL and CUDA to speed-up their research and simulations.

They were one of the first groups to try out OpenCL, even before StreamHPC existed. To simplify the research at the lab, Nuno Fachada created cf4ocl – a C Framework for OpenCL. During an e-mail correspondence with Nuno, I asked to tell something about how OpenCL was used within their lab. He was happy to share a short story.

We started working with OpenCL since early 2009. We were working with CUDA for a few months, but because OpenCL was to be adopted by all platforms, we switched right away. At the time we used it with NVidia GPUs and PS3’s, but had many problems because of the verbosity of its C API. There were few wrappers, and those that existed weren’t exactly stable or properly documented. Adding to this, the first OpenCL implementations had some bugs, which didn’t help. Some people in the lab gave up using OpenCL because of these initial problems.

All who started early on, recognises the problems described above. Now fast-forward to now.

Nowadays its much easier to use, due to the stability of the implementations, and the several wrappers for different programming languages. For C however, I think cf4ocl is the most complete and well documented. The C people here in the lab are getting into OpenCL again due to it (the Python guys were already into it again due to the excellent PyOpenCL library). Nowadays we’re using OpenCL for AMD and NVidia GPUs and multicore CPUs, including some Xeons.

This is what I hear more often lately: the return of OpenCL to research labs and companies, after a several years of CUDA. It’s a combination of preparing for the long-term, growing interest in exploring other and/or cheaper(!) accelerators than NVIDIA’s GPUs, and OpenCL being ready for prime-time.

♦

Do you have your story of how OpenCL is used within your lab or company? Just contact us.

Are you interested in other wrappers for OpenCL, See this list on our knowledge base.

The embedded world is so extremely flexible, because it is full of open standards. We therefore expect that big processor vendors will push harder than Google can push back. OpenCL-support is very important for GPGPU-libraries like ArrayFire, VexCL, ViennaCL – these can be ported to Android in less time.

Apple now has introduced Metal on iOS to increase the fragmentation even more. StreamHPC and friends are working hard on getting one language to have on all platforms, so we can build on bringing solutions to you. Understand that if OpenCL gets popular on Android, this increases the chance that it will get accepted on other mobile platforms like iOS and Windows Mobile/Phone.

On the other hand it is getting blocked wherever it can, as GPGPU brings unique apps. A RenderScript-only or Metal-only app is good for sales of one type of smartphone – good for them, bad for developers who want to target the whole market.

Getting the current status

To get more insight on the current situation, Pavan Yalamanchili of ArrayFire has created a spreadsheet (click here to edit yourself). It is publicly editable, so anybody can help complete it. Be clear about the version of Android you are running, as for instance in 4.4.4 there are possibly some blocks thrown up by Google. If you found drivers, but did not get OpenCL running, please put that in the notes. You can easily find out if your smartphone supports OpenCL, using this OpenCL-Info app. Thanks in advance of helping out!

Why not just RenderScript?

We think that RenderScript can be built on top of OpenCL. This helps allowing new programming languages and finding the optimal programming-solution faster than just trusting Google engineers – solving this problem is not about being smart, but about being open to more routes.

Same is for Metal, which even tries to replace both OpenCL and OpenGL. Again it is a higher level language which can be expressed in OpenGL and OpenCL.

Let’s see if Apple and Google serve their dedicated developers, or if we-the-developers must serve them. Let’s hope for the best.

When copying data from global to local memory, you often see code like below (1D data):
[raw]

if (get_group_id(0)==0) {
  for (int i=0; i < N; i++) {
      data_local[i] = data_global[offset+i]
  }
}
mem_fence(CLK_LOCAL_MEM_FENCE);

[/raw]
This can be replaced this with an asynchronous copy with the function async_work_group_copy, which results in more manageable and cleaner code. The function behaves like an asynchronous version of memcpy() you know from C++.

The Khronos registry async_work_group_copy provides asynchronous copies between global and local memory and a prefetch from global memory. This way it’s much easier to hide the latency of the data-transfer. In de example below, you effectively get free time to do the do_other_stuff() – this results in faster code.

As I could not find a good code-snippets online, I decided to clean-up and share some of my code. Below is a kernel that uses a patch of size (offset*2+1) and works on 2D data, flattened to a float-array. You can use it for standard convolution-like kernels.

The code is executed on workgroup-level, so there is no need to write code that makes sure it’s only executed by one work-item.

[raw]

kernel void using_local(const global float* dataIn, local float* dataInLocal) {
    event_t event;
    const int dataInLocalWidth = (offset*2 + get_local_size(0));
        
    for (int i=0; i < (offset*2 + get_local_size(1)); i++) {
        event = async_work_group_copy(
             &dataInLocal[i*dataInLocalWidth],
             &dataIn[(get_group_id(1)*get_local_size(1) - offset + i) * get_global_size(0) 
                 + (get_group_id(0)*get_local_size(0)) - offset],
             dataInLocalWidth,
             event);
   }
   do_other_stuff(); // code that you can execute for free
   wait_group_events(1, &event); // waits until the copy has finished.
   use_data(dataInLocal);
}

[/raw]

On the host (C++), the most important part:
[raw]

cl::Buffer cl_dataIn(*context, CL_MEM_READ_ONLY|CL_MEM_HOST_WRITE_ONLY, sizeof(float) 
          * gsize_x * gsize_y);
cl::LocalSpaceArg cl_dataInLocal = cl::Local(sizeof(float) * (lsize_x+2*offset) 
          * (lsize_y+2*offset));
queue.enqueueWriteBuffer(cl_dataIn, CL_TRUE, 0, sizeof(float) * size_x * size_y, dataIn);
cl::make_kernel kernel_using_local(cl::Kernel(*program,"using_local", &error));
cl::EnqueueArgs eargs(queue,cl::NullRange ,cl::NDRange(gsize_x, gsize_y), 
          cl::NDRange(lsize_x, lsize_y));
kernel_using_local(eargs, cl_dataIn, cl_dataInLocal);

[/raw]
This should work. Some have the preference to do local initialisation in the kernel, but I prefer not to do this JIT.

This code might not work optimal if you have special tricks for handling the outer border. If you see any improvement, please share via the comments.

Valgrind is a great tool for finding possible memory leaks in code written in C, C++, Java, Perl, Python, assembly code, Fortran, Ada, etc. I use it to check out if the provided code is ok, before I start porting it to GPU-code. It finds one of those devils in the details. But also for finding my own bugs when writing OpenCL-code, it has given me good feedback. Unfortunately it does not work well with optimised libraries, such as the OpenCL-driver from AMD.

You’ll get problems like below, which clutters the output.

==21436== Conditional jump or move depends on uninitialised value(s)
==21436==    at 0x6993DF2: ??? (in /usr/lib/fglrx/libamdocl64.so)
==21436==    by 0x6C00F92: ??? (in /usr/lib/fglrx/libamdocl64.so)
==21436==    by 0x6BF76E5: ??? (in /usr/lib/fglrx/libamdocl64.so)
==21436==    by 0x6C048EA: ??? (in /usr/lib/fglrx/libamdocl64.so)
==21436==    by 0x6BED941: ??? (in /usr/lib/fglrx/libamdocl64.so)
==21436==    by 0x69550D3: ??? (in /usr/lib/fglrx/libamdocl64.so)
==21436==    by 0x69A6AA2: ??? (in /usr/lib/fglrx/libamdocl64.so)
==21436==    by 0x69A6AEE: ??? (in /usr/lib/fglrx/libamdocl64.so)
==21436==    by 0x69A9D07: ??? (in /usr/lib/fglrx/libamdocl64.so)
==21436==    by 0x68C5A53: ??? (in /usr/lib/fglrx/libamdocl64.so)
==21436==    by 0x68C8D41: ??? (in /usr/lib/fglrx/libamdocl64.so)
==21436==    by 0x68C8FB5: ??? (in /usr/lib/fglrx/libamdocl64.so

How to fix this cluttering? Continue reading “Valgrind suppression file for AMD64 on Linux” →

You can’t ignore accelerators when designing a new cluster for HPC anymore. Back in 2010 I suggested to use GPUs to enter the Top 500 with a budget of only €38k. It takes ten times more now, as almost everybody started to use accelerators. To get into the November top 500 would roughly take a cluster of 150 TFLOPS.

I’d like to give you a list of what you can expect for 2014, and to help you design your HPC cluster with recent hardware. The focus should be on OpenCL-capable hardware, as open standards can prepare you better for upgrades in the future. So, this is also a guess on what we can see in the November Top 500, based on current information.

There are currently professional solutions from NVIDIA, AMD, Intel and Altera. I’ve searched the web and asked around for what would be the upcoming offers. You will find the results bellow. But information should continue to flow; please add your remarks in the comments, so we get the best information through collaboration.

Comparison: mentioning the Double Precision GFLOPS of the accelerators only. The theoretical GFLOPS can not be reached in real-world benchmarks. Therefore, DGEMM is used as an indication of the maximum realistic GFLOPS. The efficiencies of other benchmarks (like Linpack) are all lower.

NVIDIA Tesla

NVIDIA Tesla is the current market leader with Tesla K20 and K20X. By the end of 2013 they announced K40 (GK110b-architecture), which is 10% to 20% faster than the K20X (see table). This is 10% faster in max GFLOPS, but also 10% due to architecture-improvements. It’s not a huge difference, but the new Maxwell-architecture is more promising. The problem is that high-end Maxwell is not expected for this year. There are several rumours around what’s going on, but the official one is that there are problems with 20nm. I’ve had this confirmed by different sources, but will, of course, keep you up-to-date on Twitter.

I could not find good enough information on The K40x. It has been also very quiet around the current architectures on their yearly GDC conference. My expectations are that they will want to kick in hard with Maxwell in 2015. For 2014 they’ll focus on keeping their current customers happy in a different way. For now, let’s assume the K40X is 10% faster.

So, for this year it will be K40. Here’s an overview:

• Peak 1.43 DP TFLOPS theoretical
• Peak 1.33 DP TFLOPS DGEMM (93% efficiency)
• 5.65 GFLOPS/Watt DGEMM
• Needs 122 GPUs to get 150 TFLOPS DGEMM
• Lowest streetprice is $4800. $585,600 for 122 GPUs.

AMD FirePro

Just like the Tesla K40 and the Intel Xeon Phi, AMD offers accelerators with a lot of memory. The S10000 and S9000 are their current server-offers, but are still based on their older architectures. Their latest architecture is only available for gamers (i.e. R9 290X) and workstations (i.e. W9100). Now, with the recent announcement of the W9100, we have an indication of what this server-accelerator would cost, and look like. I expect this card to launch soon. I even expected it to be launched before the W9100.

What is interesting about the W9100 is the high memory transfer rate and the large memory. Assuming they need to pack the S9150 in 225 Watt and don’t change the design much to launch soon, they need to under-clock it like 22%. I think they can use 235 Watts (like the K40). Nevertheless, I want to be realistic.

So, what about the new FirePro S9000 with latest GCN, the S9150? An overview:

• Peak 2.0 DP TFLOPS theoretical
• Peak 1.6 DP TFLOPS DGEMM (at 80% efficiency, to be safe)
• 7.1 GFLOPS/Watt DGEMM
• Needs 94 GPUs to get 150 TFLOPS DGEMM
• No prices available yet – AMD mostly prices lower than NVIDIA. $371,907 for 93 GPUs, when priced at $3999.

Update: DGEMM of 90% is reached. Then we get 1.8 DP TFLOPS DGEMM and 8.3 GFLOPS/Watt DGEMM. As a result, you need 84 GPUs only to get to the 150 TFLOPS.

Intel Xeon Phi

Intel currently offers 3110, 5110 and 7110 Xeon Phi’s. In the past months they added the 3120, 5120 and 7120. The 7120 uses 300 Watt, which needs special casing to cool this passively cooled card. I don’t quite understand this. I could compare it better to the W9100 and a heavily overclocked K40, or use lower numbers like I did above with the FirePro. But, as you can see, it doesn’t even compare with 300 Watts.

The OpenCL-drivers have been improved this year, which is more promising news. The guess here is wether they will launch a new 7130, or a 7200 or none at all. All the news and rumours speak of 2015 and 2016, for a more integrated memory and a socket-version(!) of the XeonPhi.

For this year the Xeon Phi 7120 would be their top-offer. It compares well with AMD’s W9100 if it comes to memory: 16GB GDDR5 and 352 GB/s.

• Peak 1.21 DP TFLOPS theoretical
• Peak 1.07 DP TFLOPS DGEMM (at 80% efficiency)
• 3.56 GFLOPS/Watt DGEMM
• Needs 140 Phi’s to get 150 TFLOPS DGEMM
• Costs $4129 officially, $578,060 for 140.

Altera FPGAs

With OpenCL it finally got possible to run SIMD-focused software on FPGAs. OpenCL 2.0 also has some improvements for FPGAs, making it interesting for mature software that needs low-latency or less power-usage. In other words: software that has been designed on GPUs and measurements show that lower latency would out-compete others on the market who use GPUs, or that the electricity-bill makes the CFO sad. Understand that FPGAs do compete with the above three, but have their own performance hot spots and therefore it’s hard to compare.

I don’t expect the big entry in this year’s Top 500, but I’m watching FPGA progresses closely. Xilinx is also entering this market, but I don’t get much response (if any) to the emails I send to them. For next year’s article I hope to include FPGAs as a true competitor. If you need low-power or low-latency, then you’d better take your time to research FPGA potential for your business this year.

Conclusion

Open standards

For those who don’t know, I tend to prefer open standards. The main reason is that switching hardware is easier, it gives you space to experiment. AMD, Intel and Altera support OpenCL 1.2 and will start later this year with 2.0, whereas NVIDIA lags over 2 years and only supports OpenCL 1.1. The results are now very visible: due to problems with Maxwell, you’ll need to postpone your plans to 2015 if you code in CUDA. There is one way to pressure them, though: port your code to OpenCL, buy Intel or AMD hardware, and then let NVidia know you want this flexibility.

Green 500

You might have noticed the big differences between the GFLOPS/Watt. Where this is important is in the Green 500, the list of energy efficient supercomputers. The goal of today’s supercomputers is that they are mentioned in the top 10 of both lists. If you build an efficient cluster (say 2 CPUs + 4 GPUs), you can get to 70-80% of max DGEMM performance. Below is a list for 75%:

• AMD FirePro – 7.10 GFLOPS/Watt DGEMM -> 5.33 GFLOPS/Watt @ 75%
• NVIDIA Tesla – 5.65 GFLOPS/Watt DGEMM -> 4.24 GFLOPS/Watt @ 75%
• Intel XeonPhi – 3.56 GFLOPS/Watt DGEMM ->2.67 GFLOPS/Watt @ 75%

Currently this list is lead by a cluster with K20X GPUs, steaming out 4.50 GFLOPS/Watt, which has even 86% of max DGEMM.

In other words: if the FirePro gets out in time, then the green 500 could be full of FirePro GPUs.

Update November 2014: here is the Green top 5.

The winner

Since there are only three offers, they are all winners. What matters is the order.

1. AMD FirePro – 16GB with its fast memory, is  the clear winner in DGEMM performance. The negative side: CUDA-software needs to be ported to OpenCL (we can do that for you).
2. NVIDIA Tesla – Second to everything from FirePro (bandwidth, memory size, GFLOPS, price). The negative side: its OpenCL-support is outdated.
3. Intel XeonPhi – Same as FirePro when it comes to memory. Nevertheless, it’s 60% slower in DGEMM and 50% less efficient. The negative side: 300 Watt for a server.

I am happy to see AMD as a clear winner after years of NVIDIA leading the pack. As AMD is the most prominent supporter of OpenCL, this could seriously democratise HPC in times to come.

[bordered_box border_color=” background_color=’#C1DAD6′]

Need to port CUDA to extremely fast OpenCL? Hire us!

If you order a cluster from AMD instead of NVIDIA, you effectively get our services for free.

[/bordered_box]

At Intel they have CPUs (Xeon, Ivy Bridge), GPUs (Isis) and Accelerators (Xeon Phi). OpenCL enables each processor to be used to the fullest and they now promote it as such. Watch the below video and see their view on why OpenCL makes a difference for Intel’s customers.

This is important, because till recently Intel was more pushing OpenMP and their proprietary solutions. I think it has something to do with the specialised processors that can be programmed with OpenCL, such as DSPs and FPGAs. Intel has always made generic processors that solve problems best for most. Customers of OpenCL happen to be the ones that could not be served with generic processors and preferred FPGAs and DSPs, before they tried GPUs. By showing that Intel can do OpenCL, they show they are a trustworthy partner to handle the problems in a few years, when  the current problems can be handled by Intel processors.

Of course the Xeon Phi is also a good reason. The latest drivers have shown a huge improvement in performance, and that has increased Intel’s confidence in OpenCL for sure.

At StreamHPC we are very happy that Intel now openly promotes OpenCL and invests in it – this will increase trust in the programming language.

A small side-note. The differences between the Windows-drivers and Linux-drivers are somewhat vague: under Linux, the CPU is visible, but not supported officially. This makes development of multi-processor software not as straightforward as discussed in the video. Probably this will be more extensive in the future, as Intel only officially supports OpenCL on a processor when it’s very stable.

Khronos just announced three OpenCL based releases:

•  SYCL 1.2 Provisional Spec – Abstraction Layer for Leveraging C++ and OpenCL
• WebCL 1.0 Final Spec – JavaScript bindings to OpenCL
• OpenCL 2.0 Adopters Program – Conformance for OpenCL 2.0 implementations

Below I’ve quoted the summaries. For each of these I’ve prepared articles, but due to lack of time haven’t been able to finish and publish them. So for now some remarks after the summaries.

Khronos Releases SYCL 1.2 Provisional Specification

Programming abstraction layer to enable applications and high-level frameworks to leverage C++ and OpenCL for heterogeneous parallel acceleration

March 19, 2014 – San Francisco, Game Developer’s Conference – The Khronos™ Group today announced the release of SYCL™ 1.2 as a provisional specification to enable community feedback.  SYCL is a royalty-free, cross-platform abstraction layer that enables the development of applications and frameworks that build on the underlying concepts, portability and efficiency of OpenCL™, while adding the ease-of-use and flexibility of C++.  For example, SYCL can provide single source development where C++ template functions can contain both host and device code to construct complex algorithms that use OpenCL acceleration – and then enable re-use of those templates throughout the source code of an application to operate on different types of data.

https://www.khronos.org/news/press/khronos-releases-sycl-1.2-provisional-specification

Higher level languages are very important, as OpenCL is simply too low-level. SYCL is another effort to help researching & improving this area, as we haven’t found the holy grail. Languages like C++AMP and RenderScript claim they can replace OpenCL, but we all know that some implementations of those languages have been done on top of OpenCL.

Khronos Releases WebCL 1.0 Specification

JavaScript bindings to OpenCL brings heterogeneous parallel computing to Web browsers

March 19, 2014 – San Francisco, Game Developer’s Conference – The Khronos™ Group today announced the ratification and public release of the WebCL™ 1.0 specification.  Developed in close cooperation with the Web community, WebCL extends the capabilities of HTML5 browsers by enabling developers to offload computationally intensive processing to available computational resources such as multicore CPUs and GPUs.  WebCL defines JavaScript bindings to OpenCL™ APIs that enable Web applications to compile OpenCL C kernels and manage their parallel execution.  Like WebGL™, WebCL is expected to enable a rich ecosystem of JavaScript middleware that provides access to accelerated functionality to a wide diversity of Web developers.

https://www.khronos.org/news/press/khronos-releases-webcl-1.0-specification

WebCL gets more and more attention, even before it was even official. It would be interesting to see the same growth to higher level language as we have with OpenCL now. for this reason we started the Learning WebCL website, to help you learn WebCL in the future.

Khronos Launches OpenCL 2.0 Adopters Program

Conformance tests now available to certify OpenCL 2.0 implementations

March 19, 2014 – San Francisco, Game Developer’s Conference – The Khronos™ Group today announced the availability of the official conformance test suite for the OpenCL 2.0 specification, making it possible for implementers to certify that their implementations are officially conformant thorough the Khronos OpenCL Adopters Program.  Khronos has also released a set of header files for OpenCL 2.0 and an updated specification with a number of clarifications and corrections to the specification first released in November 2013.

https://www.khronos.org/news/press/khronos-launches-opencl-2.0-adopters-program

Finally the headers are open. Stay tuned for an extensive OpenCL 1.2 vs OpenCL 2.0 comparison, which I have prepared but were unable to finish without the header files.

I hope you are as happy with these announcements as I am. This tells me that OpenCL is ready for real business.

Khronos just sent out the below message to Press and Game Developers. To my understanding, there are many game devs under the readers of this blog, so I’d like you to share the message with you.

JOIN KHRONOS GROUP AT GDC 2014 SAN FRANCISCO
Press Conference, Technology Sessions and Refreshment OasisWe invite you to attend one or more of the Khronos sessions taking place in the Khronos meeting room just off the Moscone show floor. For detailed information on each session, and to register please visit: https://www.khronos.org/news/events/march-meetup-2014.

PRESS CONFERENCE

• WHEN: Wednesday March 19 at 10:00 AM (Reception 9:30 AM)
• WHERE: Room 262, West Mezzanine Level, (behind Official Press Room)
• GUESTS: Members of the Press and Industry by Invitation*
• RSVP: Jon Hirshon, Horizon PR jh@horizonpr.com

Members of the press are invited to attend the Khronos Press Conference, held jointly again this year with consortium PCGA (PC Gaming Alliance). Khronos will issue significant news on OpenGL ES, WebCL, OpenCL, and several more Khronos technologies, and PCGA will issue news about 2013 Gaming Market numbers. Updates will be delivered by Khronos and PCGA Executives, with insights made by David Cole of DFC and Jon Peddie of Jon Peddie Research.

DEVELOPER SESSIONS

• WHEN: Wednesday March 19 & Thursday March 20; Session Times Below
• WHERE: Room 262 – West Mezzanine Level, Moscone Center
• GUESTS: All GDC attendees**
• RSVP: https://www.khronos.org/news/events/march-meetup-2014

All GDC attendees** are invited to the Khronos Developer Sessions where experts from the Khronos Working Groups will deliver in-depth updates on the latest developments in graphics and media processing. These sessions are packed with information and provide a great opportunity to:

• Hear about the latest updates from the gurus that invented these technologies
• See leading-edge demos & applications
• Put your questions to members of the Khronos working groups
• Meet with other community members

SESSION SCHEDULE

Wednesday March 19

• 3:00 – 4:00 : OpenCL & SPIR
• 4:00 – 5:00 : OpenVX, Camera and StreamInput
• 5:00 – 6:00 : OpenGL ES
• 6:00 – 7:00 : OpenGL

Thursday March 20

• 3:00 – 3:50 : WebCL
• 4:00 – 4:50 : Collada and glTF
• 5:00 – 7:00 : WebGL

SESSION REGISTRATION
For information and to register, visit:https://www.khronos.org/news/events/march-meetup-2014

REFRESHMENT OASIS

• WHEN: Wednesday March 19 & Thursday March 20; from 10 AM to 7 PM
• WHERE: Room 270, West Mezzanine Level
• GUESTS: All GDC attendees**
• RSVP: https://www.khronos.org/news/events/march-meetup-2014

We thought “Refreshment Oasis” sounded like a nice way to say “sit down and have a cup of coffee while we keep working!”  Khronos is happy to offer a hospitality suite conveniently located next to our primary meeting room (and the official GDC Press room) to showcase Khronos Member technology demos and offer a place for GDC guests, Khronos Members and Marketing staff to meet.  You are welcome to just drop by for a chat, or please email Michelle@GoldStandardGroup.org to arrange a meeting with any Work Group Chairs, Khronos Execs or Marketing Team.

We look forward to seeing you at the show!

*Admittance to the Press Conference is open to all GDC registered Press, and to members of industry on a “Seating Available” basis.  Space is limited so reserve your seat today.

** Admittance to the KHRONOS sessions is FREE but: (1) all attendees must have a GDC Exhibitor or Conference Pass to gain entry to the Khronos meeting room area (GDC tickets details http://www.gdconf.com) and (2) all attendees MUST REGISTER for the individual Khronos API sessions. We expect demand to be high and space is limited.

With open standards becoming more important in the very diverse computer-game industry, Khronos is also growing. If you are in this industry  and want to know (or influence) the landscape for the coming years, you should attend.

This article actually discusses the question: is GPGPU a solution for the masses, or is it for niche-products? For the latter open standards matter a lot less, as you will read.

If you watch the below video on sale&marketing by Victor Antonio, then you get what is so difficult about open standards: It pushes all companies using the standard into a focus on becoming the best. Indeed, survival of the fittest may be the base of (true) capitalism and giving the best products. Problem is that competition on price is not safe for the future of the company.

The key is specialisation, or creating unique value. The below video discusses this. The difference between “a feature” and “unique value” is a discussion on its own, you really should have with your team on your own products. Continue reading “Commodity and Open Standards – why OpenCL matters” →

Wanting to test your OpenCL-software on specific hardware? From now on, that is possible by logging in on StreamHPCs test-servers.

Update: new prices. Got feedback it should compete with Amazon EC2.

During the beta-period (February to April) we have available:

[list1]

• Dual FirePro S10000 (total ~11.8 TFLOPS single precision, ~2.9 TFLOPS double precision).
• Several embedded GPU-boards attached.

[/list1]

By request more servers will be added, but for now we start lean.

You’ll get:

[list1]

• 64 bit Linux server.
• A secure SSH access with chrooted harddisk space.
• Full NDA in case StreamHPC staff needs to assist.
• Both shared and dedicated usage possible.
• Assistance via mail and skype.

[/list1]

The costs for shared hours are €1,- per hour, for private hours €10,- €5,- per hour. Discounts are available for academics and existing customers (also from past trainings) – just contact us. Goal of the shared hours is to setup the software, do basic tests, but not to do intensive benchmarks.

We hope you can now make a better decision what hardware to choose, or to have your paper’s conclusions based on more recent hardware.

Want more info or have special requests? Call +31854865760 (office) or +31645400456 (cell), or use the contact form.

Michael Leahy spoke on AnDevCon’13 about OpenCL on Android. Enjoy the overview!

Subjects (globally):

• What is OpenCL
• 13 dwarfs
• RenderScript
• Demo

Mr.Leahy is quite critical about Google’s recent decisions to try to block OpenCL in favour of their own proprietary RenderScript Compute (now mostly referred to as just “RenderScript” as they failed on pushing twin “RenderScript Graphics”, now replaced with OpenGL).

Around March ’13 I submitted a proposal to speak about OpenCL on Android at AnDevCon in November shortly after the “hidden” OpenCL driver was found on the N4 / N10. This was the first time I covered this material, so I didn’t have a complete idea on how long it would take, but the AnDevCon limit was ~70 mins. This talk was supposed to be 50 minutes, but I spoke for 80 minutes. Since this was the last presentation of the conference and those in attendance were interested enough in the material I was lucky to captivate the audience that long!

I was a little concerned about taking a critical opinion toward Google given how many folks think they can create nothing but gold. Afterward I recall some folks from the audience mentioning I bashed Google a bit, but this really is justified in the case of suppression of OpenCL, a widely supported open standard, on Android. In particular last week I eventually got into a little discussion on G+ with Stephen Hines of the Renderscript team who is behind most of the FUD being publicly spread by Google regarding OpenCL. One can see that this misinformation continues to be spread toward the end of this recent G+ post where he commented and then failed to follow up after I posted my perspective: https://plus.google.com/+MichaelLeahy/posts/2p9msM8qzJm

And that’s how I got in contact with Micheal: we both are irritated by Google’s actions against our favourite open standards. Microsoft has long learned that you should not block, only favour. But Google lacks the experience and believes they’re above the rules of survival.

Apparently he can dish out FUD, but can’t be bothered to answer challenges to the misinformation presented. Mr. Hines is also the one behind shutting down commentary on the Android issue tracker regarding the larger developer communities ability to express their interest in OpenCL on Android.

Regarding a correction. At the time of the presentation given the information at the time I mentioned that Renderscript is using OpenCL for GPU compute aspects. This was true for the Nexus 4 and 10 for Android 4.2 and likely 4.3; in particular the Nexus 10 using the Mali GPU from Arm. The N4 & N10 were initially using OpenCL for GPU compute aspects for Renderscript. Since then Google has been getting various GPU manufacturers to make a Renderscript driver that doesn’t utilize OpenCL for GPU compute aspects.

I hope you like the video and also understand why it remains important we keep the discussion on Google + OpenCL active. We must remain focused on the long-term and not simply accept on what others decide for us.

The main problem of discrete GPUs is that memory needs to be transferred from CPU-memory to GPU-memory. Luckily we have SoCs (GPU and CPU in one die), but still you need to do in-memory transfers as the two processors cannot access memory outside their own dedicated memory-regions. This is due the general architecture of computers, which did not take accelerators into account. Von Neumann, thanks!

HSA tries to solve this, by redefining the computer-architecture as we know it. AMD founded the HSA-foundation to share the research with other designers of SoCs, as this big change simply cannot be a one-company effort. Starting with 7 founders, it has now been extended to a long list of members.

Here I try to give an overview of what HSA is, not getting into much detail. It’s a TL;DR.

What is Heterogeneous Systems Architecture (HSA)?

It consists mainly of three parts:

• new memory-architecture: hUMA,
• new task-queueing: hQ, and
• an intermediate language: HSAIL.

The basic idea is to give GPUs and DSPs about the same rights as a CPU in a computer, to enable true heterogeneous computing.

hUMA (Heterogeneous Uniform Memory Access)

HSA changes the way memory is handled by eliminating a hierarchy in processing-units. In a hUMA architecture, the CPU and the GPU (inside the APU) have full access to the entire system memory. This makes it a shared memory system as we know it from multi-core and multi-CPU systems.

hQ (Heterogeneous Queuing)

HSA gives more rights to GPUs and DSPs, leveraging work from the CPU. Compared to the Von Neumann architecture, the CPU is not the Central Processing Unit anymore – each processor can be in control and create tasks for itself and the other processors.

HSAIL (HSA Intermediate Language)

HSAIL is a sort of virtual target for HSA-hardware. Hardware-vendors focus on getting HSAIL compiled to their processor instruction sets, and developers of high-level languages target HSAIL in their compilers. This is a proven concept of evolving complex hardware-software projects.

It is pretty close to OpenCL SPIR, which has comparable goals. Don’t see them as competitors, but two projects which both need different freedoms and will work along.

What is in it for OpenCL?

OpenCL 2.0 has support for Shared Virtual Memory, Generic Address Space and Recursive Functions. All supported by HSA-hardware.

OpenCL-code can be compiled to SPIR, which compiles to HSAIL, which compiles to HSA-hardware. When the time comes that HSAIL starts supporting legacy hardware, SPIR can be skipped.

HSA is going to be supported in OpenCL 1.2 via new flags – watch this thread.

Final words

Two companies not there: Intel and Nvidia. Why? Because they want to do it themselves. The good news is that HSA is large enough to define the new architecture, making sure we get a standard. The bad news is that the two outsiders will come up with an exception for whatever reason, which gives a need for exceptions in compilers.

You can read more on the  website of the HSA-foundation or ask me in the comments below.

Thursday 13 February 2014 the first Khronos meetup in will take place. We expect a small group, so the location will be cozy and there will be enough time to talk with a beer. First round is on me, admission is free.

Goal is to learn about open media-standards from Khronos and others. So when OpenCV is discussed, we’ll also talk OpenVX. The target group is programmers and Indy developers who are interested in creating multi-OS and multi-device software.

Program

I am very thrilled to tell that Ton Roosendaal of the Blender Foundation will talk about the releationship between his Blender and Khronos OpenGL.

Second Maarten and Jurjen of ThreeDee Media will talk about WebGL, from a technical and a market view. Is WebGL ready for prime-time?

Then you can show your stuff. For that I’ll bring a good laptop with Windows 8.1 and Ubuntu 13.10 64.

Prepare for Meetup today!

See the Meetup-page for more information. See you there!

While CUDA has had the advantage of having many more libraries, this is no longer its main advantage if it comes to linear algebra. If one thing changed over the past year, then it is linalg library-support for OpenCL. The choices have been increased at a continuous rate, as you can see the below list.

A general remark when using these libraries. When using them you need to handle your data-transfers and correct data-format, with great care. If you don’t think it through, you won’t get the promised speed-up. If not mentioned, then free.

Subject	CUDA	OpenCL
FFT	CUFFT The NVIDIA CUDA Fast Fourier Transform library (cuFFT) provides a simple interface for computing FFTs up to 10x faster. By using hundreds of processor cores inside NVIDIA GPUs, cuFFT delivers the…	clFFT is a software library containing FFT functions written in OpenCL. In addition to GPU devices, the library also supports running on CPU devices to facilitate debugging and multicore programming.
Linear Algebra	MAGMA MAGMA is a collection of next generation, GPU accelerated ,linear algebra libraries. Designed for heterogeneous GPU-based architectures. It supports interfaces to current LAPACK and BLAS standards.	clMAGMA is an OpenCL port of MAGMA for AMD GPUs. The clMAGMA library dependancies, in particular optimized GPU OpenCL BLAS and CPU optimized BLAS and LAPACK for AMD hardware, can be found in the AMD Accelerated Parallel Processing Math Libraries (APPML).
Sparse Linear Algebra	CUSP CUSP is an open source C++ library of generic parallel algorithms for sparse linear algebra and graph computations on CUDA architecture GPUs. CUSP provides a flexible, high-level interface for manipulating sparse matrices and solving sparse linear systems.	clBLAS implements the complete set of BLAS level 1, 2 & 3 routines. Please see Netlib BLAS for the list of supported routines. In addition to GPU devices, the library also supports running on CPU devices to facilitate debugging and multicore programming.ViennaCL is a free open-source linear algebra library for computations on many-core architectures (GPUs, MIC) and multi-core CPUs. The library is written in C++ and supports CUDA, OpenCL, and OpenMP. In addition to core functionality and many other features including BLAS level 1-3 support and iterative solvers, the latest release ViennaCL 1.5.0 provides many new convenience functions and support for integer vectors and matrices.VexCL is a vector expression template library for OpenCL/CUDA. It has been created for ease of GPGPU development with C++. VexCL strives to reduce amount of boilerplate code needed to develop GPGPU applications. The library provides convenient and intuitive notation for vector arithmetic, reduction, sparse matrix-vector products, etc. Multi-device and even multi-platform computations are supported.
Random number generation	cuRAND The NVIDIA CUDA Random Number Generation library (cuRAND) delivers high performance GPU-accelerated random number generation (RNG). The cuRAND library delivers high quality random numbers 8x…	The Random123 library is a collection of counter-based random number generators (CBRNGs) for CPUs (C and C++) and GPUs (CUDA and OpenCL). They are intended for use in statistical applications and Monte Carlo simulation and have passed all of the rigorous SmallCrush, Crush and BigCrush tests in the extensive TestU01 suite of statistical tests for random number generators. They are not suitable for use in cryptography or security even though they are constructed using principles drawn from cryptography.
	CUDA Math Library The CUDA Math library is an industry proven, highly accurate collection of standard mathematical functions. Available to any CUDA C or CUDA C++ application simply by adding “#include math.h” in…	Looking into the details of what the CUDA math lib exactly is.
AI	GPU AI for Board Games A technology preview with CUDA accelerated game tree search of both the pruning and backtracking styles. Games available: 3D Tic-Tac-Toe, Connect-4, Reversi, Sudoku and Go.	There are many tactics to speed up such algorithms. This CUDA-library can therefore only be used for limited cases, but nevertheless it is a very interesting research-area. Ask us for an OpenCL based backtracking and pruning tree searching, tailored for your problem.
Dense Linear Algebra	EM Photonics CULA Tools Provides accelerated implementations of the LAPACK and BLAS libraries for dense linear algebra. Contains routines for systems solvers, singular value decompositions, and eigenproblems. Also provides various solvers. Free (with limitations) and commercial.	See ViennaCL, VexCL and clBLAS above. Kudos to the CULA-team, as they were one of the first with a full GPU-accelerated linear algebra product.
Fortran	IMSL Fortran Numerical Library The IMSL Fortran Numerical Library is a comprehensive set of mathematical and statistical functions available that offloads CPU work to NVIDIA GPU hardware where the cuBLAS library is utilized. Free (with limitations) and commercial.	OpenCL-FORTRAN is not available yet. Contact us, if you have interest and wish to work with a pre-release once available.
Subject	AccelerEyes ArrayFire Comprehensive GPU function library, including functions for math, signal processing, image processing, statistics, and more. Interfaces for C, C++, Fortran, and Python. Integrates with any CUDA-program. Free (with limitations) and commercial.	ArrayFire 2.0 is also available for OpenCL. Note that currently fewer functions are supported in the OpenCL-version than are supported in CUDA-ArrayFire, so please check the OpenCL documentation for supported feature list.Free (with limitations) and commercial.
Subject	NVIDIA Performance Primitives The NVIDIA Performance Primitives library (NPP) is a collection of over 1900 image processing primitives and nearly 600 signal processing primitives that deliver 5x to 10x faster performance than…	Kudos for NVIDIA for bringing it all at one place. OpenCL-devs have to do some googling for specific algorithms.

So the gap between CUDA and OpenCL is certainly closing. CUDA provides a lot more convenience, so OpenCL-devs still have to keep reading blogs like this one to find what’s out there.

As usual, if you have additions to this list (free and commercial), please let me know in the comments below or by mail. I also have a few more additions to this list myself – depending on your feedback, I might represent the data differently.

If one thing can be said about Europe, is that it is quite diverse. Each country  solves or fails to solve its own problems individually, while European goals are not always well-cared for. Nevertheless, you can notice things changing. One of the areas where things have changed, is that of HPC. HPH  has always been a well-interconnected research in Europe (with its centre in CERN), but there is a catch-up going on for the European commercial market. The whole of Europe has new goals set for better collaboration between companies and research institutes with programs like Horizon 2020. This means that it becomes necessary to improve interconnections among much larger groups.

In most magazines HPC is a section of a broader scope. This is also very important as this introduces HPC to more people. Now, I’d like to concentrate on the focus magazines. There are mainly two magazines available: Primeur Magazine and HPC Today.

Primeur Magazine

De Netherlands based magazine Primeur-magazine has been around for years, with HPC-news from Europe, video-channel, knowledge-base, calendar and more. Issues of past weeks can be read online (for free), but news can also be delivered via a weekly e-mail (paid service, prices range from €125 to €4000 per company/institute, depending on size).

They focus on being a news-channel for what is going on in in the HPC-world, both in the EU and the US. Don’t forget to follow them on Twitter.

HPC Today

Update: the magazine changed its name from HPC Magazine to HPC Today.

With several editions (Americas, Europe and France), websites and TV channels, the France based HPC Today brings an actionable coverage of the HPC and Big Data news, technologies, uses and research. Subscriptions are free, as the magazine is paid-for by advertisements. They balance their articles by targeting both people who deeply understand malloc() and people who want to know what is going on. Their readers are developers and researchers from both academic and private sectors.

With the change to HPC Today the content has slightly changed according the requests from the readers: less science, more HPC news. For the rest it’s about the same.

To get an idea of how they’re doing, check the partners of HPC Magazine: Teratec, ISC events and SC conference.

Other European HPC sources

Not all information around the web is nicely bundled in a PDF. Find a small list below to help you start.

InSiDE

The German National Supercomputing Centers HLRS, LRZ, NIC publish the online magazine InSiDE (Innovatives Supercomputing in Deutschland) twice a year. The articles are available in html and PDF. It gives a good overview of what is going on in Germany and Europe. There are no ways to subscribe via e-mail, so it would be better to put it in your calendar.

e-IRG

The e-Infrastructure initiative‘s main goal is to support the creation of a political, technological and administrative framework for an easy and cost-effective shared use of distributed electronic resources across Europe.

e-IRG is not a magazine, but it is a good start to find information about HPC in Europe. Their knowledge-base is very useful when trying to get an overview what is there in Europe: Projects, Country-statistics, Computer centers and more. They closely collaborate with Primeur-magazine, so can you see some overlap in the information.

PRACE Digest

PRACE (Partnership for Advanced Computing in Europe) is to enable high impact scientific discovery, as well as engineering research and development across all disciplines to enhance European competitiveness for the benefit of society. PRACE seeks to achieve this mission by offering world class computing and data management resources and services through a peer review process.

The PRACE digest appears as twice a year as a PDF.

More?

Did we miss an important news-source or magazine? Let us know in the comments below!