# GPU Device 0: "Graphics Device" on Pegasus does not support Unified Memory **URL:** \ **Category:** DRIVE AGX Xavier General\ **Created:** [May 8, 2019, 4:42pm UTC](https://forums.developer.nvidia.com/t/gpu-device-0-graphics-device-on-pegasus-does-not-support-unified-memory/74393 "2019-05-08T16:42:23Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![454615](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/454615/32/11453_2.png) [@454615](https://forums.developer.nvidia.com/u/454615)\ **Post date:** [May 8, 2019, 4:42pm UTC](https://forums.developer.nvidia.com/t/gpu-device-0-graphics-device-on-pegasus-does-not-support-unified-memory/74393/1 "2019-05-08T16:42:23Z")
It seems that the Device 0: “Graphics Device” (dGPU?) does not support Unified Memory, and I wonder to know if this is intentionally design or just a bug and will be fixed in the future. (e.g. cudaMallocManaged() call cannot work on “Device 0”) I also test the sample codes provided by NVIDIA (e.g. CUDA, CUPTI), and there are some discrepancies between actual and the website info. (e.g. “Turing” Discrete GPUs (TU104 SXM2) - 130 TOPS connected to Xavier SoC over NVIDIA®NVLink™ (20 GB/s)) The sample code return “No Nvlink supported device found”, however, I supposed that CPU to dGPU is connected via NvLink (Please correct me if I am wrong), and the memory bandwidth results of Host\<-\>Device, Device\<-\>Device either on iGPU(\>250 GB/s) or dGPU(\>750 GB/s) cannot reach the theoretical values. In addition, is there any APIs can directly transfer data from iGPU to dGPU and vice versa? What is the best approach for memory management if there is no Unified Memory provided on dGPU? The deviceQuery gives the following output: Device 0: “Graphics Device” CUDA Driver Version / Runtime Version 10.0 / 10.0 CUDA Capability Major/Minor version number: 7.5 Total amount of global memory: 7680 MBytes (8052998144 bytes) (44) Multiprocessors, ( 64) CUDA Cores/MP: 2816 CUDA Cores GPU Max Clock rate: 1500 MHz (1.50 GHz) Memory Clock rate: 13 Mhz Memory Bus Width: 256-bit L2 Cache Size: 4194304 bytes Maximum Texture Dimension Size (x,y,z) 1D=(131072), 2D=(131072, 65536), 3D=(16384, 16384, 16384) Maximum Layered 1D Texture Size, (num) layers 1D=(32768), 2048 layers Maximum Layered 2D Texture Size, (num) layers 2D=(32768, 32768), 2048 layers Total amount of constant memory: 65536 bytes Total amount of shared memory per block: 49152 bytes Total number of registers available per block: 65536 Warp size: 32 Maximum number of threads per multiprocessor: 1024 Maximum number of threads per block: 1024 Max dimension size of a thread block (x,y,z): (1024, 1024, 64) Max dimension size of a grid size (x,y,z): (2147483647, 65535, 65535) Maximum memory pitch: 2147483647 bytes Texture alignment: 512 bytes Concurrent copy and kernel execution: Yes with 3 copy engine(s) Run time limit on kernels: No Integrated GPU sharing Host Memory: No Support host page-locked memory mapping: Yes Alignment requirement for Surfaces: Yes Device has ECC support: Disabled Device supports Unified Addressing (UVA): Yes Device supports Compute Preemption: Yes Supports Cooperative Kernel Launch: Yes Supports MultiDevice Co-op Kernel Launch: Yes Device PCI Domain ID / Bus ID / location ID: 1 / 1 / 0 Compute Mode: \< Default (multiple host threads can use ::cudaSetDevice() with device simultaneously) \> Device 1: “Xavier” CUDA Driver Version / Runtime Version 10.0 / 10.0 CUDA Capability Major/Minor version number: 7.2 Total amount of global memory: 24729 MBytes (25929990144 bytes) ( 8) Multiprocessors, ( 64) CUDA Cores/MP: 512 CUDA Cores GPU Max Clock rate: 1109 MHz (1.11 GHz) Memory Clock rate: 1109 Mhz Memory Bus Width: 256-bit L2 Cache Size: 524288 bytes Maximum Texture Dimension Size (x,y,z) 1D=(131072), 2D=(131072, 65536), 3D=(16384, 16384, 16384) Maximum Layered 1D Texture Size, (num) layers 1D=(32768), 2048 layers Maximum Layered 2D Texture Size, (num) layers 2D=(32768, 32768), 2048 layers Total amount of constant memory: 65536 bytes Total amount of shared memory per block: 49152 bytes Total number of registers available per block: 65536 Warp size: 32 Maximum number of threads per multiprocessor: 2048 Maximum number of threads per block: 1024 Max dimension size of a thread block (x,y,z): (1024, 1024, 64) Max dimension size of a grid size (x,y,z): (2147483647, 65535, 65535) Maximum memory pitch: 2147483647 bytes Texture alignment: 512 bytes Concurrent copy and kernel execution: Yes with 1 copy engine(s) Run time limit on kernels: No Integrated GPU sharing Host Memory: Yes Support host page-locked memory mapping: Yes Alignment requirement for Surfaces: Yes Device has ECC support: Disabled Device supports Unified Addressing (UVA): Yes Device supports Compute Preemption: Yes Supports Cooperative Kernel Launch: Yes Supports MultiDevice Co-op Kernel Launch: Yes Device PCI Domain ID / Bus ID / location ID: 0 / 0 / 0 Compute Mode: \< Default (multiple host threads can use ::cudaSetDevice() with device simultaneously) \> > Peer access from Graphics Device (GPU0) → Xavier (GPU1) : No > Peer access from Xavier (GPU1) → Graphics Device (GPU0) : No deviceQuery, CUDA Driver = CUDART, CUDA Driver Version = 10.0, CUDA Runtime Version = 10.0, NumDevs = 2 Result = PASS ---
**Author:** ![SivaRamaKrishnaNV](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/sivaramakrishnanv/32/14043_2.png) [@SivaRamaKrishnaNV](https://forums.developer.nvidia.com/u/SivaRamaKrishnaNV)\ **Post date:** [May 8, 2019, 7:47pm UTC](https://forums.developer.nvidia.com/t/gpu-device-0-graphics-device-on-pegasus-does-not-support-unified-memory/74393/2 "2019-05-08T19:47:45Z")
Dear 454615, Yes. Unified memory is not supported on dGPU. For nvlink isssue, may I know which sample have tested? If you are asking to transfer data from iGPU to dGPU, you may have to bring the data onto CPU using cudamemcpy calls in between. However, you can choose EGLStream to transfer frames from iGPU to dGPU to avoid unneccessary memcpy operations. You can choose pinned memory as unified memory is not available. Please check [url][https://docs.nvidia.com/cuda/cuda-for-tegra-appnote/index.html#memory-selection[/url]](https://docs.nvidia.com/cuda/cuda-for-tegra-appnote/index.html#memory-selection%5B/url%5D) ---
**Author:** ![TomNVIDIA](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/tomnvidia/32/14181_2.png) [@TomNVIDIA](https://forums.developer.nvidia.com/u/TomNVIDIA)\ **Post date:** [October 12, 2021, 8:05pm UTC](https://forums.developer.nvidia.com/t/gpu-device-0-graphics-device-on-pegasus-does-not-support-unified-memory/74393/3 "2021-10-12T20:05:38Z")
Closed on October 12, 2021, 8:05pm UTC