郑紫阳10295048 0f23e6a2ef Add RVV SIMD specialization for scalar quantizer distance compute (#5539) ...

Summary:
This PR adds RISC-V Vector Extension SIMD specialization for the scalar
quantizer distance computation, following the codec/quantizer/similarity
specialization already present for other SIMD levels. The kernels use the
runtime vector-length aware m8 vector configuration and are shared across
all RVV hardware widths, instead of assuming a fixed vector length.

Changes
Add RVV specialized L2 / inner-product distance kernels for the scalar
quantizer codecs:

- QT_4bit / QT_4bit_uniform
- QT_6bit
- QT_8bit / QT_8bit_uniform
- QT_8bit_direct / QT_8bit_direct_signed
- QT_bf16
- QT_fp16

Each kernel reuses the reconstructed (quantizer) L2 / IP formulation that
avoids per-dimension reconstruction, keeping the hot loop in the integer
domain and applying the final scale at the tail.

Performance
Cmd: 1M 768 <SQ> 32 100 16 1 1000 1 <metric>  (search ms/query, lower is better)
Δ_SQ%: SQ scalar baseline -> RVV;
Δ_F%: Faiss flat baseline -> RVV.

| 序号 | QT_TYPE               | Metric | F1(ms) | SQ1(ms) | F2(ms) | SQ2(ms) | Δ_SQ%   | Δ_F%   |
|------|-----------------------|--------|--------|---------|--------|---------|---------|--------|
| 01   | QT_4bit               | L2     | 1.841  | 6.231   | 1.824  | 1.450   | -76.73% | -0.92% |
| 02   | QT_4bit               | IP     | 1.652  | 6.086   | 1.674  | 1.273   | -79.08% | +1.33% |
| 03   | QT_4bit_uniform       | L2     | 1.806  | 2.560   | 1.806  | 1.135   | -55.66% | +0.00% |
| 04   | QT_4bit_uniform       | IP     | 1.612  | 6.007   | 1.597  | 1.244   | -79.29% | -0.93% |
| 05   | QT_6bit               | L2     | 1.801  | 5.701   | 1.805  | 1.500   | -73.69% | +0.22% |
| 06   | QT_6bit               | IP     | 1.608  | 5.706   | 1.619  | 1.249   | -78.11% | +0.68% |
| 07   | QT_8bit               | L2     | 1.821  | 3.736   | 1.907  | 1.394   | -62.69% | +4.72% |
| 08   | QT_8bit               | IP     | 1.704  | 3.378   | 1.730  | 1.277   | -62.20% | +1.53% |
| 09   | QT_8bit_direct        | L2     | 1.977  | 0.280   | 1.947  | 0.054   | -80.71% | -1.52% |
| 10   | QT_8bit_direct        | IP     | 1.709  | 0.458   | 1.740  | 0.099   | -78.38% | +1.81% |
| 11   | QT_8bit_direct_signed | L2     | 1.581  | 3.234   | 1.572  | 0.761   | -76.47% | -0.57% |
| 12   | QT_8bit_direct_signed | IP     | 1.740  | 0.414   | 1.748  | 0.148   | -64.25% | +0.46% |
| 13   | QT_8bit_uniform       | L2     | 1.943  | 3.204   | 1.928  | 0.927   | -71.07% | -0.77% |
| 14   | QT_8bit_uniform       | IP     | 1.727  | 3.121   | 1.744  | 0.947   | -69.66% | +0.98% |
| 15   | QT_bf16               | L2     | 1.862  | 2.889   | 1.894  | 1.466   | -49.26% | +1.72% |
| 16   | QT_bf16               | IP     | 1.619  | 2.846   | 1.793  | 1.204   | -57.70% | +10.75% |
| 17   | QT_fp16               | L2     | 2.011  | 5.691   | 1.950  | 1.570   | -72.41% | -3.03% |
| 18   | QT_fp16               | IP     | 1.797  | 5.584   | 1.790  | 1.189   | -78.71% | -0.39% |

Pull Request resolved: https://github.com/facebookresearch/faiss/pull/5539

Reviewed By: mnorris11

Differential Revision: D117914328

Pulled By: juancarpio27

fbshipit-source-id: 879863b9ab4da6d1c8685892ccc3d64190975181

2026-09-17 13:34:43 -07:00

..

actions

Fix ROCm CI: build in a dedicated conda env instead of the runner's broken base (#5545)

2026-09-10 08:01:09 -07:00

scripts

Add Windows ARM64 support to CI (#5544)

2026-08-28 10:06:58 -07:00

workflows

Add RVV SIMD specialization for scalar quantizer distance compute (#5539)

2026-09-17 13:34:43 -07:00

ISSUE_TEMPLATE.md

Update ISSUE_TEMPLATE.md (#1462)

2020-10-20 04:37:50 -07:00