### 🔀 [#130](https://github.com/ikawrakow/ik_llama.cpp/pull/130) - Q6_K_R4

| **Author** | `ikawrakow` |
| :--- | :--- |
| **State** | ❌ **Closed** |
| **Created** | 2024-12-10 |
| **Updated** | 2024-12-10 |

---

#### Description

Follow up of #118, #119, #120, #121, #122, #123, #129  for `Q6_K`. 

If nothing else `Q6_K` is routinely used for the output tensor, so having a better `Q6_K` performance would be useful.

We get a large speedup on `ARM_NEON` and non-negligible gains on `AVX2/Zen4`.  Here is `PP-512` for LLaMA-3.1-8B on `Zen4` (Ryzen-7950X), `ARM_NEON` (M2-Max) and `AVX2` (Ryzen-5975WX)

| Platform |  Threads | Q6_K | Q6_K_R4 | Speedup |
| ---: | ---: | ---: | ---: | ---: |
| ARM_NEON |  8 |  57.57 ± 0.61  | 83.25 ± 0.81  | 1.446 |
| Zen4            | 16 | 195.20 ± 0.74  | 243.25 ± 0.31  | 1.246 |
| AVX2           | 32 | 194.51 ± 0.35  | 264.16 ± 0.44  | 1.358 |

Except on `ARM_NEON`, where TG performance is slightly lower for small numbers of threads, we gain even for TG. Here results for TG-128 on LLaMA-3.1-8B with different numbers of threads:

| Platform |  Threads | Q6_K | Q6_K_R4 | Speedup |
| ---: | ---: | ---: | ---: | ---: |
| ARM_NEON |  2 |  7.46 ± 0.03  | 7.35 ± 0.01  | 0.985 |
|                       |  4 |  13.88 ± 0.02  | 13.80 ± 0.01  | 0.994 |
|                       |  8 |  18.31 ± 0.16   |  18.57 ± 0.14  | 1.014 |
| Zen4            | 1 |  5.38 ± 0.00  | 7.94 ± 0.00  |  1.476 |
|                      | 2 |  8.93 ± 0.00 | 10.38 ± 0.00  |  1.162 |
|                      | 4 |  9.97 ± 0.27  | 10.18 ± 0.01  |  1.021 |
| AVX2           | 2 | 4.75 ± 0.00    | 5.78 ± 0.01  | 1.217 |
|                     | 4 | 7.57 ± 0.00    | 8.47 ± 0.00  | 1.119 |
|                     | 8 |  8.23 ± 0.00   | 9.14 ± 0.00  | 1.111 |

With this Zen4 implementation, for TG the available memory bandwidth is fully saturated with just 2 threads!