Files
xserv/crates/xserv-kernels/src/layernorm.rs
Gahow Wang 4c3f914459 kernels/cuda: paged-attention kernel, dispatch, pinned host memory
CUDA layer for the paged-KV + swap work:
- csrc: new paged_attention.cu plus updates across attention/gemm/norm/
  activation/embedding/reduce kernels and common.cuh.
- xserv-kernels: new dispatch module and kernel-binding updates.
- xserv-cuda: cudaMallocHost/FreeHost bindings + PinnedBuffer (host swap
  pool backing) and offset-aware D2H/H2D copies used to move KV blocks
  between the GPU pool and pinned host memory.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-05-28 19:58:36 +08:00

41 lines
1.8 KiB
Rust

use std::ffi::c_void;
use xserv_tensor::{DType, Device, Tensor};
unsafe extern "C" {
fn launch_layernorm_f32(x: *const c_void, gamma: *const c_void, beta: *const c_void,
out: *mut c_void, rows: i32, hidden_size: i32, eps: f32, stream: *mut c_void);
fn launch_layernorm_bf16(x: *const c_void, gamma: *const c_void, beta: *const c_void,
out: *mut c_void, rows: i32, hidden_size: i32, eps: f32, stream: *mut c_void);
}
pub fn layernorm(x: &Tensor, gamma: &Tensor, beta: &Tensor, eps: f32) -> Tensor {
assert!(x.ndim() >= 1);
assert!(x.is_contiguous() && gamma.is_contiguous() && beta.is_contiguous());
assert!(matches!(x.device(), Device::Cuda(_)));
let hidden_size = *x.shape().last().unwrap();
assert_eq!(gamma.shape(), &[hidden_size]);
assert_eq!(beta.shape(), &[hidden_size]);
let rows = x.numel() / hidden_size;
assert!(rows <= i32::MAX as usize, "too many rows for i32 kernel param");
assert!(hidden_size <= i32::MAX as usize, "hidden_size too large for i32 kernel param");
let out = Tensor::empty(x.shape(), x.dtype(), x.device());
unsafe {
match x.dtype() {
DType::F32 => launch_layernorm_f32(
x.data_ptr() as _, gamma.data_ptr() as _, beta.data_ptr() as _,
out.data_ptr() as *mut c_void,
rows as i32, hidden_size as i32, eps, std::ptr::null_mut(),
),
DType::BF16 => launch_layernorm_bf16(
x.data_ptr() as _, gamma.data_ptr() as _, beta.data_ptr() as _,
out.data_ptr() as *mut c_void,
rows as i32, hidden_size as i32, eps, std::ptr::null_mut(),
),
_ => panic!("unsupported dtype for layernorm"),
}
}
out
}