The Turing GPU

The Turing GPU

Looking at the Turing GPU, there is a lot of stuff you can recognize, but starting at Turing there certainly have been fundamental block changes in the architecture; the SM (Streaming Multiprocessor) clusters have separated, and now are core separated isolated blocks. Keep in mind that the base building block for all Turing GPUs is the mac daddy TU102, that is the flagship GPU that has been used on the GeForce RTX 2080 Ti. The RTX 2080 Super and 2070 Super use the TU104, the RTX 2060 TU106. In essence, the TU106 is the more simplified revision of the TU102, but it shares the same architecture. It's fabbed at 12nm FFN.

Turing GPU Specifications

Gamers will immediately look at the shader processors, the Quadro RTX 8000 has 4608 of them enabled and, since everything with bits is in multitudes of eight, while looking at the GPU die photos; a TU104 based GeForce RTX 2080 Super has 48 SMs (streaming multiprocessors) each holding 64 cores = 3072 Shader processors. This GPU is fabbed on an optimized 12nm TSMC FinFET+ node.

GeForce	RTX 2080 Super	RTX 2080	RTX 2070 Super	RTX 2070 FE	RTX 2060 Super	RTX 2060 FE
GPU	TU104	TU104	TU104	TU106	TU106	TU106
Shader cores	3072	2944	2560	2304	2176	1920
Transistor count	13.6 Billion	13.6 Billion	13.6 Billion	10.8 Billion	10.8 Billion	10.8 Billion
Base frequency	1640 MHz	1515 MHz	1605 MHz	1410 MHz	1470 MHz	1365 MHz
Boost frequency	1815 MHz	1800 MHz	1770 MHz	1710 MHz	1650 MHz	1680 MHz
Memory	8GB GDDR6	8GB GDDR6	8GB GDDR6	8GB GDDR6	8GB GDDR6	6GB GDDR6
Memory frequency	15.5 Gbps	14 Gbps	14 Gbps	14 Gbps	14 Gbps	14 Gbps
Memory bus	256-bit	256-bit	256-bit	256-bit	256-bit	192-bit
Memory bandwidth	496 GB/s	448 GB/s	448 GB/s	448 GB/s	448 GB/s	336 GB/s
L2 Cache	4096 KB	4096 KB	4096 KB	4096 KB	4096 KB	4096 KB
RT cores	48	46	40	36	34	30
Tensor cores	384	48	288	288	240	240
Texture units	192	184	184	144	136	120
ROPs	64	64	64	64	64	48
TDP	250W	225W	190W	185W	175W	160W
NVLink	Yes	Yes	Yes	No	No	No
Price	$ 699	$ 799	$ 499	$ 599	$ 399	$ 349

  * reference/founder ed. specifications

Turing architecture

We'll try and be brief here, but Turing is a new and completely overhauled architecture that actually has gotten a new SM (Streaming Multiprocessor) design. As I mentioned, it has a bit of everything, but mostly it hints towards Volta. Two SMs are included per TPC (Texture / Processor Cluster - a group made up of several SMs). Each SM has a total of 64 FP32 Cores and 64 INT32 Cores. Now before you get all confused, yes, that is radically different from Pascal (GeForce series 1000) which had one SM per TPC and 128 FP32 Cores per SM. The Turing SM architecture supports parallel execution of FP32 and INT32 operations, independent thread scheduling similar to the Volta GV100 GPU. That's also described as concurrent execution of FP32 and INT32 operation. Each Turing SM holds eight Turing Tensor Cores. With that out of the way, have a peek at the block diagram below.

Each Turing SM is partitioned into four processing blocks, each holds 16 FP32 Cores, 16 INT32 Cores, two Tensor Cores, one warp scheduler, and one dispatch unit. Each block includes a new L0 instruction cache and a 64 KB register file. The four processing blocks share a combined 96 KB L1 data cache/shared memory. Traditional graphics workloads partition the 96 KB L1/shared memory as 64 KB of dedicated graphics shader RAM and 32 KB for texture cache and register file spill area. Compute workloads can divide the 96 KB into 32 KB shared memory and 64 KB L1 cache, or 64 KB shared memory and 32 KB L1 cache.

Concurrent Execution of Floating Point (fp32) and Integer Instructions (int32)

Turing’s SM initiates a new unified architecture for shared memory, L1, and texture caching. This unified design allows the L1 cache to leverage resources, increasing its bandwidth by 2x per TPC compared to Pascal, and allows it to be reconfigured to grow larger when shared memory allocations are not using all the shared memory capacity. The Turing L1 can be as large as 64 KB in size, combined with a 32 KB per SM shared memory allocation, or it can reduce to 32 KB, allowing 64 KB of allocation to be used for shared memory. Turing’s L2 cache capacity has also been increased. Combining the L1 data cache with the shared memory reduces latency and provides higher bandwidth than the L1 cache implementation used previously in Pascal GPUs. NVIDIA claims these changes in SM enable Turing to achieve 50% improvement in delivered performance per CUDA core. Turing GPUs add larger and faster L2 caches in addition to the new GDDR6 memory subsystem. The TU102 GPU ships with 6 MB of L2 cache, double the 3 MB of L2 cache that was offered in the prior generation GP102 GPU used in the TITAN XP. TU102 also provides significantly higher L2 cache bandwidth than GP102. Like prior generations of NVIDIA GPUs, each ROP partition in Turing contains eight ROP units and each unit can process a single-color sample. A full TU102 chip would contain 12 ROP partitions for a total of 96 ROPs. The RTX 2080 and 2070 have 64 of these.