hi,it will support gpu ,for example ARM mali gpu,

[zif520]

hi sh1r0, I am very interested in your project,Are there plan to supply gpu? for example ARM mali opencl 1.1 gpu

[sh1r0]

I would say that it's possible, but I'm not sure when. Currently, if you are interested in caffe w/ OpenCL support, you can refer to https://github.com/BVLC/caffe/pull/2610.

[naibaf7]

@sh1r0 It should be possible to get BVLC/caffe#2610 to work on android. It can probably be done by replacing the Caffe used in this project by the https://github.com/naibaf7/caffe branch and some minor adaptions/fixes.

[sh1r0]

@naibaf7 :+1: But I took a look at your branch, and I found that the commits are too much to make the branch like a patch to be easily applied to the upstream master branch. Would you like to rebase your branch?

[naibaf7]

@sh1r0 Yes and I guess you would need to use 32 bit indexing (pointers) instead of 64 bit indexing for Android devices. What requirements would you have to be able to integrate this?

[sh1r0]

@naibaf7 Yes, I guess so. :stuck_out_tongue: I think a branch which is rebased to the latest master branch (https://github.com/BVLC/caffe/commit/03a84bf464dd47bcec9ac943f0229a758c627f05) should be enough for me to have some trials. Thanks.

[zif520]

@naibaf7 @sh1r0
hi,I've run it by compared naibaf7/caffe to caffe-android-lib ,it work well on cpu used EIGEN, but it will failed when run greentea_memset() on GPU mode(mali T880 opencl 1.1,use 32 bit indexing ). it failed when run viennacl::ocl::enqueue(),I am not familiar with opencl,so learn some about it to fix the problem later. could you give some suggestions to me? thanks!

[naibaf7]

@zif520 Did you change int_tp and int_tpc both to 32bit types for both the OpenCL and C++ part of the code?

https://github.com/naibaf7/caffe/blob/master/include/caffe/definitions.hpp and https://github.com/naibaf7/caffe/blob/master/src/caffe/greentea/cl_headers/header.cl

however it might break if you just change it, so I'll verify and fix that.

I have a phone with an Adreno 330 GPU that should also be OpenCL ready... might try to fix it up myself :)... the great news is that OpenCL-Z (from PlayStore) reports a valid libOpenCL.so version 1.2 on that one!

[zif520]

@naibaf7 there is still some troubles in it ,i will spent some days to fix it , and then https://github.com/amd/OpenCL-caffe/issues/17 said clblas 2.4 support opencl 1.1 ,i also will try it . OpenCL-Z reports my telephone only supply opencl1.1

[naibaf7]

@zif520 I am currently making my branch ready for 32 bit indexing again, so that both 64 bit and 32 bit work. Then it should be able to compile and run on Android 1.1 devices.

It is not necessary to compile and use clBLAS with my branch, ViennaCL comes with a built-in BLAS that should work on mobile devices with OpenCL 1.1

Can you share what you have done so far? (adaptions, code, ...) that would speed up the process.

[zif520]

@naibaf7 yes! i will share it when it is completed,it is popular to use caffe(mxnet and so on) on telephone ,many people wang to do that .

[naibaf7]

@sh1r0 I currently don't have the time for a complete rebase - this has to wait a bit.

@zif520 What's the progress? Is it working with my latest updates?

[zif520]

@naibaf7 i am sorry,i go home just beause of new year,i will come back 2016,01,04,

[sh1r0]

@naibaf7 OK, that's fine. I tried to merge my branch onto yours for some trials in the early stage. To see my progress, you can take a look at opencl_dev.

And there are some issues I found according to my tests:

• CPU does not work as a OpenCL device (runtime error)
• Running on GPU is about 5 times slower than in pure CPU mode (CPU_ONLY with OpenBLAS)

Note: my test device is with Qualcomm Snapdragon 801 (Qualcomm Krait 400 and Qualcomm Adreno 330) and the support of OpenCL 1.2.

I'm not quite sure if I miss anything I need to take care of, as I'm not familiar with OpenCL. :p

Thanks.

[bhack]

@sh1r0 I don't know how amd clblas or viennacl backends are optimized for this kind of devices. Qualcomm has its own Snapdragon optimized BLAS implementation but it is still CPU only.

[naibaf7]

@sh1r0 Ok cool, at least you got it working!

Now, what is the runtime error that you get with using the CPU on OpenCL? I use a CPU BLAS with CPU devices instead of ViennaCL-BLAS or clBLAS, so that might make issues here.

As for performance, it should definitely not be that slow. But to identify where the culprit is, I'd need to have some layer-wise timings to see what exactly runs slow. Maybe something I can also have a look at, as I have an Adreno 330 as well. Do you know how to do that quickly?

When you enumerate OpenCL devices, is the order the same as in OpenCL-Z?

[sh1r0]

@naibaf7 Yes, it's really cool to have OpenCL works.

Sorry, I'm not sure what the problem might be, as I just got a segmentation fault when specifying CPU as the target device.

To get layer-wise timings, I think tools/caffe time is a good choice. However, with OpenCL build, I failed to make any executable run successfully on Android. I got ViennaCL: FATAL ERROR: Could not find kernel 'fillbuffer_float' from program '' for classification (cpp_classification) ~~and CANNOT LINK EXECUTABLE: cannot locate symbol "_ZN5caffe3NetIfEC1ERKSsNS_5PhaseEPKS1_" referenced by "./caffe"... for caffe~~. That's weird. EDIT: For caffe, got Segmentation fault.

Yes, the order are consistent to that in OpenCL-Z.

[naibaf7]

@sh1r0 Ok thanks, I'll try to work out what's going wrong.

Might it be that the binaries do not call set_mode and SetDevice properly? ViennaCL: FATAL ERROR: Could not find kernel 'fillbuffer_float' from program '' would imply the OpenCL kernels weren't compiled.

[zif520]

@sh1r0 you will refer @naibaf7 ' s code in caffe.cpp:test(),you add setdevices() will fix it,at first ,you will init device

[naibaf7]

@zif520 Yes, here, it is also important to mention that the device must be set before any solver or network is loaded. Knowledge of which device should be used is ultimately required to compile kernels, allocate memory and dispatch network/solver initialization.

It is even possible to have multiple devices work on multiple networks in parallel, but then the rules are as follows:

• Caffe must be initialized with SetDevices on the main thread, providing a complete list of the devices to be used.
• SelectDevice can be used to switch the device. When initializing networks on the main thread, select the device before creating a network or solver on that device.
• The networks can be trained in parallel by using multiple host threads. In every thread, SelectDevice can switch to a different device. This selection will be thread local.
• This threading feature should also work when being used in Android AsyncTasks, Java Threads or in Python Multithreading (without getting into GIL locks), making it very convenient to use.

[sh1r0]

@zif520 Thanks, I've got CPU working as a OpenCL device. (I used SetDevice only before.) But there might have other issues in tools/caffe such that it still does not work.

@naibaf7 I got some benchmark results, please refer to the link. time.cpp is basically caffe time. The number of iterations is 10 for cpu mode and 1 for gpu mode (as it takes ~6 minutes for a single iteration). I found that there are little difference between using cpu and gpu as the OpenCL device. And as for forward timings, gpu mode (OpenCL) is ~70x slower than cpu mode.

[naibaf7]

@sh1r0 I think now you benchmarked the OpenCL GPU twice:

    Caffe::SetDevices(gpus);
    Caffe::set_mode(Caffe::GPU);
    Caffe::SetDevice(gpus[0]);

should be either:

    Caffe::set_mode(Caffe::GPU);
    Caffe::SetDevice(gpus[0]);

or:

    Caffe::set_mode(Caffe::GPU);
    Caffe::SetDevices(gpus);
    Caffe::SelectDevice(gpus[0], false);

Besides, I think the ViennaCL GEMM for convolution seems really unsuitable for the Adreno GPU then. I don't know of any BLAS that is optimized for mobile GPUs. Probably a better performance can even be reached by implementing a simple direct convolution instead of using an explicit GEMM at all. Maybe @karlrupp has an idea on this.

[bhack]

@naibaf7 A tuning issue on Adreno was opened at https://github.com/clMathLibraries/clBLAS/issues/136

[naibaf7]

@bhack Thanks, good to know. However ViennaCL-BLAS seems to have optimization/tuning issues on this as well (which is what we are currently using in this Android-OpenCL experiment). It is a bit unfortunate, since nVidia has well optimized cuBLAS for most devices, while other vendors have basically nothing to offer (yet).

[bhack]

@naibaf7 Have you experimented with https://github.com/ptillet/isaac? Probably could be an alternative path if clBLAS continue to not attract contributions by other vendors. /cc @ptillet

[bhack]

Also Google https://github.com/halide/Halide/tree/master/apps/linear_algebra could be benchmarked on android.

[naibaf7]

@bhack @zif520 @sh1r0 Added ISAAC compile support to CMake and GNU Makefiles on my branch, if anyone fancies to try. It did not speed up on my GT650 or Intel HD4000. Maybe it can work on mobile.

[bhack]

@ptillet What is the status?

[karlrupp]

@naibaf7 We had a detailed look at mobile GPUs over the summer. Our findings were fairly disappointing: Even with extensive code generation and autotuning we could not get anywhere close to peak (exception: NVIDIA Tegra). Even synthetic FLOP-intensive code did not work well, indicating that OpenCL compiler support still needs much more love.

[naibaf7]

@karlrupp Thanks for clarification, even though that is not good news, it indicates that the fault lies with the compiler / OpenCL libraries of the vendors and not with our code.

It is very disappointing indeed, I thought by now there would be more efforts and interest by hardware vendors to have solutions ready to compete against nVidia.

[sh1r0]

@naibaf7 Oh, I thought Net instance is running on the device which is specified in the constructor, so I did in this way:

Net<float> caffe_net(FLAGS_model, caffe::TRAIN, Caffe::GetDevice(device_id, true));

I would like to benchmark cpu (device 1) as a opencl device, and I tried both

Caffe::set_mode(Caffe::GPU);
Caffe::SetDevice(gpus[1]);

and

Caffe::set_mode(Caffe::GPU);
Caffe::SetDevices(gpus);
Caffe::SelectDevice(gpus[1], false);

with

Net<float> caffe_net(FLAGS_model, caffe::TRAIN, Caffe::GetDefaultDevice());

I got segmentation fault during runtime on both cases. :(

---

To all: It's really disappointing to know that.