Bug#886327: clblas: Fails on Intel 6th gen. (Skylake) iGPU and Beignet OpenCL driverl works with the Intel one

[a.marmodoro at googlemail.com]

Source: clblas
Version: 2.12-1
Severity: normal

The (packaged) testing program 'clblas-client' triggers a failure when testing SGEMM operations on an integrated GPU, Intel 'Skylake':

$ lspci 
00:00.0 Host bridge: Intel Corporation Skylake Host Bridge/DRAM Registers (rev 07)
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 530 (rev 06)
[...]

when the system uses the Debian 'beignet-opencl-icd' package to provide OpenCL support:

/tmp$ clBLAS-client -v 1 -g
Error of clblas_sgemm against cblas_sgemm = 509.276398 
        StatisticalTimer:: Pruning 0 samples from clfunc
        StatisticalTimer:: Pruning 0 samples from clGemm
BLAS kernel execution time < ns >: 175
BLAS kernel execution Gflops < 2.0*M*N*K/time >: 23967.5
OPENCL_V_THROWERROR< CL_INVALID_COMMAND_QUEUE > (330): releasing command queue
terminate called after throwing an instance of 'std::runtime_error'
  what():  OPENCL_V_THROWERROR< CL_INVALID_COMMAND_QUEUE > (330): releasing command queue
Aborted

/tmp$ 

The test passes if the proprietary Intel OpenCL driver is instead used, from: https://software.intel.com/en-us/articles/opencl-drivers#philinux

/tmp$ clBLAS-client -v 1 -g
Error of clblas_sgemm against cblas_sgemm = 0.000000 
        StatisticalTimer:: Pruning 1 samples from clfunc
        StatisticalTimer:: Pruning 0 samples from clGemm
BLAS kernel execution time < ns >: 226253
BLAS kernel execution Gflops < 2.0*M*N*K/time >: 18.5381

/tmp$

Suggested fix: Please consider documenting the bug / referencing to the possibly more up-to-date and complete Intel OpenCL driver, to allow easier deployment of the 'libclblas2' and related packages. Further tips can also be mentioned from: https://wiki.tiker.net/OpenCLHowTo

Thank you very much!
--
Alberto.


-- System Information:
Debian Release: 9.3
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.14.10 (SMP w/4 CPU cores)
Locale: LANG=en_IE.UTF-8, LC_CTYPE=en_IE.UTF-8 (charmap=UTF-8), LANGUAGE=en_IE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)