Day 1: OpenCL and Intel i7-6770HQ Skull Canyon

Playing with Intel OpenCL SDK and Etherneum mining

About the hardware

The Intel 6th-generation Core i7-6770HQ [1] is a neat little beast. Here are lspci [LSPCI], cpuinfo [CPUINFO], and clinfo [CLINFO] from an Intel NUC6i7KYK with Ubuntu server 16.04.

Some benchmarks [2] [3].

OpenCL "Installable Client Drivers" (ICD)

In order to prevent every OpenCL runtime library from fighting the other one to become the one and only libOpenCL.so of the system, a generic/dummy library was created, which dispatch the OpenCL calls to one of the available ICD of the system: from AMD, NVidia, Intel or others. More details at [4].

ICD register themselves in /etc/OpenCL/vendors/ by creating a simple text file which contains the path the actual OpenCL library. For example, the path for Intel runtime is

~$ cat /etc/OpenCL/vendors/intel.icd
/opt/intel/opencl/libIntelOpenCL.so

First step, install the generic OpenCL library, along with the official OpenCL headers (only needed for development). clinfo is also very useful to list the available devices:

sudo apt install ocl-icd-libopencl1
sudo apt install opencl-headers
sudo apt install clinfo

Of course, if clinfo is executed now, no device is found because there is no real OpenCL library yet:

~$ clinfo
Number of platforms                               0

Intel OpenCL (GPU+CPU)

Intel OpenCL SDK and runtime are found at [5]. Direct link to the package [6], installation notes [7] and release notes [8].

From the installation notes

Intel OpenCL driver require Linux kernel 4.8

Ubuntu 16.04 with the default kernel works fairly well but some core features (i.e. device enqueue, SVM memory coherency, VTune support) won’t work without kernel patches. This configuration has been minimally validated to prove that it is viable to suggest for experimental use, but it is not fully supported or certified.

SWM memory coherency? [9]

If you prefer to avoid patching your linux kernel, you will need kernel 4.8 or newer. On Ubuntu server 16.04, you might need to install a Hardware Enablement pack (aka HWE) to get a more recent kernel:

sudo apt install linux-generic-hwe-16.04
intel-opencl-r5.0-63503.x86_64.tar.xz
    etc/
        ld.so.conf.d/
            libintelopencl.conf
                /opt/intel/opencl
        OpenCL/
            vendors/
                intel.icd
                    /opt/intel/opencl/libIntelOpenCL.so
    opt/
        LICENSE                     docs
        NOTICES                     docs
        igdclbif.bin
        kernel-4.4-xcode.patch      kernel patch (no patch needed for linux-4.8 and later)
        kernel-4.7.patch            kernel patch (no patch needed for linux-4.8 and later)
        libIntelOpenCL.so           main OpenCL library
        libOpenCL.so                If you don't use OpenCL ICD
        libOpenCL.so.1              If you don't use OpenCL ICD
        libcommon_clang.so          OpenCL kernels are built on-demand for each device
        libcommon_clang_legacy.so
        libiga64.so
        libigdbcl.so
        libigdccl.so
        libigdfcl.so
        libigdfcl_legacy.so
        libigdmcl.so
        libigdrcl.so
        libmd.so

After moving the files at the right places, do not forget to run sudo ldconfig in order to refresh the ld cache.

You maybe notice that the CPU is not found in the OpenCL device. Using sudo strace clinfo, you can see if some specific libraries are search and not found. For example, libnuma.so was missing on my system:

sudo apt install libnuma1

AMD OpenCL (CPU-only)

AMD OpenCL CPU SDK [10] also works with Intel CPU.

Etherneum mining

Two softwares are needed: the Etherneum client, and Etherneum miner. There are multiple implementation of each. An (outdated?) post about starting to mine [11].

To create a new account with the Etherneum client:

~$ geth account new
WARN [09-30|11:09:00] No etherbase set and no accounts found as default
Your new account is locked with a password. Please give a password. Do not forget this password.
Passphrase:
Repeat passphrase:
Address: {ed318e9348d616594f1286072c3b6fc8b61a8fdf}

Pre-built binary of an open-source Etherneum miner can be found at [12].

My command to mine:

sudo ./ethminer -G -S eu1.ethermine.org:4444 -FS us1.ethermine.org:4444 -O 0xed318e9348d616594f1286072c3b6fc8b61a8fdf.nuc --farm-recheck 200

You will notice that ethminer only uses GPU devices even if CPU devices are available with sufficient memory (> 2GB).

In this file [13]

_platforms[platform_num].getDevices(
    CL_DEVICE_TYPE_GPU | CL_DEVICE_TYPE_ACCELERATOR,
    &devices
);

Add CL_DEVICE_TYPE_CPU to the bitfield here, to select CPU as well.

At around 1.3 MHash/second, you are loosing money [14]. This Intel chip is not very adapted because of its limited CPU/GPU-to-memory bandwidth, which is the most important for Etherneum mining. High-end GPUs with on chip HBM2 memory achieve 30 MHash/sec. Intel memory CPU/GPU memory bandwidth: 34GB/s, NVidia Quadro GP100 bandwidth: 720GB/s.

Wall power consumption at full load is 77W [15].

Intel GPU tools

Would be nice to a kind of top command for GPU like there is for CPU, right? See [16].

Check intel_gpu_top [17].

References

[1]Intel ARK, Core i7-6770HQ, https://ark.intel.com/products/93341/Intel-Core-i7-6770HQ-Processor-6M-Cache-up-to-3_50-GHz
[2]Geekbench, Intel Skull Canyon, https://browser.geekbench.com/v4/compute/223790
[3]GfxBench, Intel® Core™ i7-6770HQ CPU with Iris™ Pro Graphics 580, https://compubench.com/device.jsp?D=Intel%28R%29+Core%28TM%29+i7-6770HQ+CPU+with+Iris%28TM%29+Pro+Graphics+580&testgroup=overall
[4]Andreas Klöckner's wiki, How to set up OpenCL in Linux, https://wiki.tiker.net/OpenCLHowTo
[5]OpenCL™ Drivers and Runtimes for Intel® Architecture, https://software.intel.com/en-us/articles/opencl-drivers
[6]http://registrationcenter-download.intel.com/akdlm/irc_nas/11396/SRB5.0_linux64.zip
[7]http://registrationcenter-download.intel.com/akdlm/irc_nas/11396/SRB5.0_intel-opencl-installation.pdf
[8]http://registrationcenter-download.intel.com/akdlm/irc_nas/11396/SRB5.0_intel-opencl-release-notes.pdf
[9]https://community.arm.com/processors/b/blog/posts/exploring-how-cache-coherency-accelerates-heterogeneous-compute
[10]AMD APPSDK, http://developer.amd.com/amd-accelerated-parallel-processing-app-sdk/
[11]https://www.meebey.net/posts/ethereum_gpu_mining_on_linux_howto/
[12]https://github.com/ethereum-mining/ethminer/releases
[13]https://github.com/ethereum-mining/ethminer/blob/master/libethash-cl/CLMiner.cpp
[14]https://etherscan.io/ether-mining-calculator
[15]https://www.anandtech.com/show/10343/the-intel-skull-canyon-nuc6i7kyk-minipc-review/7
[16]http://www.rkblog.rk.edu.pl/w/p/monitoring-amd-intel-and-nvidia-graphics-card-usage-under-linux/
[17]https://01.org/linuxgraphics/gfx-docs/igt/

Appendix

[LSPCI]List of PCI peripherals
$ lspci
00:00.0 Host bridge: Intel Corporation Sky Lake Host Bridge/DRAM Registers (rev 0a)
00:02.0 VGA compatible controller: Intel Corporation Sky Lake Integrated Graphics (rev 09)
00:08.0 System peripheral: Intel Corporation Sky Lake Gaussian Mixture Model
00:14.0 USB controller: Intel Corporation Sunrise Point-H USB 3.0 xHCI Controller (rev 31)
00:14.2 Signal processing controller: Intel Corporation Sunrise Point-H Thermal subsystem (rev 31)
00:16.0 Communication controller: Intel Corporation Sunrise Point-H CSME HECI #1 (rev 31)
00:1c.0 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #1 (rev f1)
00:1c.1 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #2 (rev f1)
00:1c.2 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #3 (rev f1)
00:1c.4 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #5 (rev f1)
00:1d.0 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #9 (rev f1)
00:1d.4 PCI bridge: Intel Corporation Sunrise Point-H PCI Express Root Port #13 (rev f1)
00:1f.0 ISA bridge: Intel Corporation Sunrise Point-H LPC Controller (rev 31)
00:1f.2 Memory controller: Intel Corporation Sunrise Point-H PMC (rev 31)
00:1f.3 Audio device: Intel Corporation Sunrise Point-H HD Audio (rev 31)
00:1f.4 SMBus: Intel Corporation Sunrise Point-H SMBus (rev 31)
00:1f.6 Ethernet controller: Intel Corporation Ethernet Connection (2) I219-LM (rev 31)
02:00.0 SD Host controller: O2 Micro, Inc. Device 8621 (rev 01)
03:00.0 Network controller: Intel Corporation Wireless 8260 (rev 3a)
3e:00.0 Non-Volatile memory controller: Device 1987:5007 (rev 01)
[CPUINFO]CPU info (smae info repeated for 8 cores)
ina@nuc:~$ cat /proc/cpuinfo
processor   : 0
vendor_id   : GenuineIntel
cpu family  : 6
model               : 94
model name  : Intel(R) Core(TM) i7-6770HQ CPU @ 2.60GHz
stepping    : 3
microcode   : 0x8a
cpu MHz             : 845.101
cache size  : 6144 KB
physical id : 0
siblings    : 8
core id             : 0
cpu cores   : 4
apicid              : 0
initial apicid      : 0
fpu         : yes
fpu_exception       : yes
cpuid level : 22
wp          : yes
flags               : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch epb intel_pt tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm mpx rdseed adx smap clflushopt xsaveopt xsavec xgetbv1 dtherm ida arat pln pts hwp hwp_notify hwp_act_window hwp_epp
bugs                :
bogomips    : 5183.87
clflush size        : 64
cache_alignment     : 64
address sizes       : 39 bits physical, 48 bits virtual
power management:
[CLINFO]List of OpenCL-compatible devices

platformes

Number of platforms                               2
  Platform Name                                   Intel(R) OpenCL
  Platform Vendor                                 Intel(R) Corporation
  Platform Version                                OpenCL 2.0
  Platform Profile                                FULL_PROFILE
  Platform Extensions                             cl_khr_3d_image_writes cl_khr_byte_addressable_store cl_khr_depth_images cl_khr_fp64 cl_khr_global_int32_base_atomics cl_khr_global_int32_extended_atomics cl_khr_icd cl_khr_image2d_from_buffer cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics cl_khr_spir
  Platform Extensions function suffix             INTEL

  Platform Name                                   AMD Accelerated Parallel Processing
  Platform Vendor                                 Advanced Micro Devices, Inc.
  Platform Version                                OpenCL 2.0 AMD-APP (1800.8)
  Platform Profile                                FULL_PROFILE
  Platform Extensions                             cl_khr_icd cl_amd_event_callback cl_amd_offline_devices
  Platform Extensions function suffix             AMD

platform 0, device 0

  Platform Name                                   Intel(R) OpenCL
Number of devices                                 2
  Device Name                                     Intel(R) HD Graphics
  Device Vendor                                   Intel(R) Corporation
  Device Vendor ID                                0x8086
  Device Version                                  OpenCL 2.0
  Driver Version                                  r5.0.63503
  Device OpenCL C Version                         OpenCL C 2.0
  Device Type                                     GPU
  Device Profile                                  FULL_PROFILE
  Max compute units                               72
  Max clock frequency                             950MHz
  Device Partition                                (core)
    Max number of sub-devices                     0
    Supported partition types                     by <unknown> (0x7F4600000000)
  Max work item dimensions                        3
  Max work item sizes                             256x256x256
  Max work group size                             256
  Preferred work group size multiple              32
  Preferred / native vector sizes
    char                                                16 / 16
    short                                                8 / 8
    int                                                  4 / 4
    long                                                 1 / 1
    half                                                 8 / 8        (cl_khr_fp16)
    float                                                1 / 1
    double                                               1 / 1        (cl_khr_fp64)
  Half-precision Floating-point support           (cl_khr_fp16)
    Denormals                                     Yes
    Infinity and NANs                             Yes
    Round to nearest                              Yes
    Round to zero                                 Yes
    Round to infinity                             Yes
    IEEE754-2008 fused multiply-add               Yes
    Support is emulated in software               No
    Correctly-rounded divide and sqrt operations  No
  Single-precision Floating-point support         (core)
    Denormals                                     Yes
    Infinity and NANs                             Yes
    Round to nearest                              Yes
    Round to zero                                 Yes
    Round to infinity                             Yes
    IEEE754-2008 fused multiply-add               Yes
    Support is emulated in software               No
    Correctly-rounded divide and sqrt operations  Yes
  Double-precision Floating-point support         (cl_khr_fp64)
    Denormals                                     Yes
    Infinity and NANs                             Yes
    Round to nearest                              Yes
    Round to zero                                 Yes
    Round to infinity                             Yes
    IEEE754-2008 fused multiply-add               Yes
    Support is emulated in software               No
    Correctly-rounded divide and sqrt operations  No
  Address bits                                    64, Little-Endian
  Global memory size                              6595090842 (6.142GiB)
  Error Correction support                        No
  Max memory allocation                           3297545421 (3.071GiB)
  Unified memory for Host and Device              Yes
  Shared Virtual Memory (SVM) capabilities        (core)
    Coarse-grained buffer sharing                 Yes
    Fine-grained buffer sharing                   No
    Fine-grained system sharing                   No
    Atomics                                       No
  Minimum alignment for any data type             128 bytes
  Alignment of base address                       1024 bits (128 bytes)
  Preferred alignment for atomics
    SVM                                           64 bytes
    Global                                        64 bytes
    Local                                         64 bytes
  Max size for global variable                    65536 (64KiB)
  Preferred total size of global vars             3297545421 (3.071GiB)
  Global Memory cache type                        Read/Write
  Global Memory cache size                        1572864
  Global Memory cache line                        64 bytes
  Image support                                   Yes
    Max number of samplers per kernel             16
    Max size for 1D images from buffer            206096588 pixels
    Max 1D or 2D image array size                 2048 images
    Base address alignment for 2D image buffers   4 bytes
    Pitch alignment for 2D image buffers          4 bytes
    Max 2D image size                             16384x16384 pixels
    Max 3D image size                             16384x16384x2048 pixels
    Max number of read image args                 128
    Max number of write image args                128
    Max number of read/write image args           128
  Max number of pipe args                         16
  Max active pipe reservations                    1
  Max pipe packet size                            1024
  Local memory type                               Local
  Local memory size                               65536 (64KiB)
  Max constant buffer size                        3297545421 (3.071GiB)
  Max number of constant args                     8
  Max size of kernel argument                     1024
  Queue properties (on host)
    Out-of-order execution                        Yes
    Profiling                                     Yes
  Queue properties (on device)
    Out-of-order execution                        Yes
    Profiling                                     Yes
    Preferred size                                131072 (128KiB)
    Max size                                      67108864 (64MiB)
  Max queues on device                            1
  Max events on device                            1024
  Prefer user sync for interop                    Yes
  Profiling timer resolution                      83ns
  Execution capabilities
    Run OpenCL kernels                            Yes
    Run native kernels                            No
    SPIR versions                                 1.2
  printf() buffer size                            4194304 (4MiB)
  Built-in kernels                                block_motion_estimate_intel;block_advanced_motion_estimate_check_intel;block_advanced_motion_estimate_bidirectional_check_intel
  Motion Estimation accelerator version     (Intel)   2
  Device Available                                Yes
  Compiler Available                              Yes
  Linker Available                                Yes
  Device Extensions                               cl_intel_accelerator cl_intel_advanced_motion_estimation cl_intel_device_side_avc_motion_estimation cl_intel_driver_diagnostics cl_intel_media_block_io cl_intel_motion_estimation cl_intel_planar_yuv cl_intel_packed_yuv cl_intel_required_subgroup_size cl_intel_subgroups cl_intel_subgroups_short cl_intel_va_api_media_sharing cl_khr_3d_image_writes cl_khr_byte_addressable_store cl_khr_depth_images cl_khr_fp16 cl_khr_fp64 cl_khr_global_int32_base_atomics cl_khr_global_int32_extended_atomics cl_khr_icd cl_khr_image2d_from_buffer cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics cl_khr_mipmap_image cl_khr_mipmap_image_writes cl_khr_spir cl_khr_subgroups

platform 0, device 1

Device Name                                     Intel(R) Core(TM) i7-6770HQ CPU @ 2.60GHz
Device Vendor                                   Intel(R) Corporation
Device Vendor ID                                0x8086
Device Version                                  OpenCL 2.0 (Build 475)
Driver Version                                  1.2.0.475
Device OpenCL C Version                         OpenCL C 2.0
Device Type                                     CPU
Device Profile                                  FULL_PROFILE
Max compute units                               8
Max clock frequency                             2600MHz
Device Partition                                (core)
  Max number of sub-devices                     8
  Supported partition types                     by counts, equally, by names (Intel)
Max work item dimensions                        3
Max work item sizes                             8192x8192x8192
Max work group size                             8192
Preferred work group size multiple              128
Preferred / native vector sizes
  char                                                 1 / 32
  short                                                1 / 16
  int                                                  1 / 8
  long                                                 1 / 4
  half                                                 0 / 0        (n/a)
  float                                                1 / 8
  double                                               1 / 4        (cl_khr_fp64)
Half-precision Floating-point support           (n/a)
Single-precision Floating-point support         (core)
  Denormals                                     Yes
  Infinity and NANs                             Yes
  Round to nearest                              Yes
  Round to zero                                 No
  Round to infinity                             No
  IEEE754-2008 fused multiply-add               No
  Support is emulated in software               No
  Correctly-rounded divide and sqrt operations  No
Double-precision Floating-point support         (cl_khr_fp64)
  Denormals                                     Yes
  Infinity and NANs                             Yes
  Round to nearest                              Yes
  Round to zero                                 Yes
  Round to infinity                             Yes
  IEEE754-2008 fused multiply-add               Yes
  Support is emulated in software               No
  Correctly-rounded divide and sqrt operations  No
Address bits                                    64, Little-Endian
Global memory size                              8254349312 (7.687GiB)
Error Correction support                        No
Max memory allocation                           2063587328 (1.922GiB)
Unified memory for Host and Device              Yes
Shared Virtual Memory (SVM) capabilities        (core)
  Coarse-grained buffer sharing                 Yes
  Fine-grained buffer sharing                   No
  Fine-grained system sharing                   No
  Atomics                                       No
Minimum alignment for any data type             128 bytes
Alignment of base address                       1024 bits (128 bytes)
Preferred alignment for atomics
  SVM                                           64 bytes
  Global                                        64 bytes
  Local                                         0 bytes
Max size for global variable                    65536 (64KiB)
Preferred total size of global vars             65536 (64KiB)
Global Memory cache type                        Read/Write
Global Memory cache size                        262144
Global Memory cache line                        64 bytes
Image support                                   Yes
  Max number of samplers per kernel             480
  Max size for 1D images from buffer            128974208 pixels
  Max 1D or 2D image array size                 2048 images
  Base address alignment for 2D image buffers   64 bytes
  Pitch alignment for 2D image buffers          64 bytes
  Max 2D image size                             16384x16384 pixels
  Max 3D image size                             2048x2048x2048 pixels
  Max number of read image args                 480
  Max number of write image args                480
  Max number of read/write image args           480
Max number of pipe args                         16
Max active pipe reservations                    32767
Max pipe packet size                            1024
Local memory type                               Global
Local memory size                               32768 (32KiB)
Max constant buffer size                        131072 (128KiB)
Max number of constant args                     480
Max size of kernel argument                     3840 (3.75KiB)
Queue properties (on host)
  Out-of-order execution                        Yes
  Profiling                                     Yes
  Local thread execution (Intel)                Yes
Queue properties (on device)
  Out-of-order execution                        Yes
  Profiling                                     Yes
  Preferred size                                4294967295 (4GiB)
  Max size                                      4294967295 (4GiB)
Max queues on device                            4294967295
Max events on device                            4294967295
Prefer user sync for interop                    No
Profiling timer resolution                      1ns
Execution capabilities
  Run OpenCL kernels                            Yes
  Run native kernels                            Yes
  SPIR versions                                 1.2
printf() buffer size                            1048576 (1024KiB)
Built-in kernels
Device Available                                Yes
Compiler Available                              Yes
Linker Available                                Yes
Device Extensions                               cl_khr_icd cl_khr_global_int32_base_atomics cl_khr_global_int32_extended_atomics cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics cl_khr_byte_addressable_store cl_khr_depth_images cl_khr_3d_image_writes cl_intel_exec_by_local_thread cl_khr_spir cl_khr_fp64 cl_khr_image2d_from_buffer

platform 1, device 0

  Platform Name                                   AMD Accelerated Parallel Processing
Number of devices                                 1
  Device Name                                     Intel(R) Core(TM) i7-6770HQ CPU @ 2.60GHz
  Device Vendor                                   GenuineIntel
  Device Vendor ID                                0x1002
  Device Version                                  OpenCL 1.2 AMD-APP (1800.8)
  Driver Version                                  1800.8 (sse2,avx)
  Device OpenCL C Version                         OpenCL C 1.2
  Device Type                                     CPU
  Device Profile                                  FULL_PROFILE
  Device Board Name (AMD)
  Device Topology (AMD)                           (n/a)
  Max compute units                               8
  Max clock frequency                             899MHz
  Device Partition                                (core, cl_ext_device_fission)
    Max number of sub-devices                     8
    Supported partition types                     equally, by counts, by affinity domain
    Supported affinity domains                    L3 cache, L2 cache, L1 cache, next partitionable
    Supported partition types (ext)               equally, by counts, by affinity domain
    Supported affinity domains (ext)              L3 cache, L2 cache, L1 cache, next fissionable
  Max work item dimensions                        3
  Max work item sizes                             1024x1024x1024
  Max work group size                             1024
  Preferred work group size multiple              1
  Preferred / native vector sizes
    char                                                16 / 16
    short                                                8 / 8
    int                                                  4 / 4
    long                                                 2 / 2
    half                                                 4 / 4        (n/a)
    float                                                8 / 8
    double                                               4 / 4        (cl_khr_fp64)
  Half-precision Floating-point support           (n/a)
  Single-precision Floating-point support         (core)
    Denormals                                     Yes
    Infinity and NANs                             Yes
    Round to nearest                              Yes
    Round to zero                                 Yes
    Round to infinity                             Yes
    IEEE754-2008 fused multiply-add               Yes
    Support is emulated in software               No
    Correctly-rounded divide and sqrt operations  Yes
  Double-precision Floating-point support         (cl_khr_fp64)
    Denormals                                     Yes
    Infinity and NANs                             Yes
    Round to nearest                              Yes
    Round to zero                                 Yes
    Round to infinity                             Yes
    IEEE754-2008 fused multiply-add               Yes
    Support is emulated in software               No
    Correctly-rounded divide and sqrt operations  No
  Address bits                                    64, Little-Endian
  Global memory size                              8254349312 (7.687GiB)
  Error Correction support                        No
  Max memory allocation                           2147483648 (2GiB)
  Unified memory for Host and Device              Yes
  Minimum alignment for any data type             128 bytes
  Alignment of base address                       1024 bits (128 bytes)
  Global Memory cache type                        Read/Write
  Global Memory cache size                        32768
  Global Memory cache line                        64 bytes
  Image support                                   Yes
    Max number of samplers per kernel             16
    Max size for 1D images from buffer            65536 pixels
    Max 1D or 2D image array size                 2048 images
    Max 2D image size                             8192x8192 pixels
    Max 3D image size                             2048x2048x2048 pixels
    Max number of read image args                 128
    Max number of write image args                64
  Local memory type                               Global
  Local memory size                               32768 (32KiB)
  Max constant buffer size                        65536 (64KiB)
  Max number of constant args                     8
  Max size of kernel argument                     4096 (4KiB)
  Queue properties
    Out-of-order execution                        No
    Profiling                                     Yes
  Prefer user sync for interop                    Yes
  Profiling timer resolution                      1ns
  Profiling timer offset since Epoch (AMD)        1506759285803052634ns (Sat Sep 30 10:14:45 2017)
  Execution capabilities
    Run OpenCL kernels                            Yes
    Run native kernels                            Yes
    SPIR versions                                 1.2
  printf() buffer size                            65536 (64KiB)
  Built-in kernels
  Device Available                                Yes
  Compiler Available                              Yes
  Linker Available                                Yes
  Device Extensions                               cl_khr_fp64 cl_amd_fp64 cl_khr_global_int32_base_atomics cl_khr_global_int32_extended_atomics cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics cl_khr_int64_base_atomics cl_khr_int64_extended_atomics cl_khr_3d_image_writes cl_khr_byte_addressable_store cl_khr_gl_sharing cl_ext_device_fission cl_amd_device_attribute_query cl_amd_vec3 cl_amd_printf cl_amd_media_ops cl_amd_media_ops2 cl_amd_popcnt cl_khr_spir cl_khr_gl_event