Files
xserv/crates/xserv-kernels/src/embedding.rs

102 lines
3.2 KiB
Rust

use std::ffi::c_void;
use xserv_tensor::{DType, Device, Tensor};
unsafe extern "C" {
fn launch_embedding_f32(
table: *const c_void,
token_ids: *const c_void,
out: *mut c_void,
num_tokens: i32,
hidden_size: i32,
vocab_size: i32,
stream: *mut c_void,
);
fn launch_embedding_bf16(
table: *const c_void,
token_ids: *const c_void,
out: *mut c_void,
num_tokens: i32,
hidden_size: i32,
vocab_size: i32,
stream: *mut c_void,
);
}
/// Embedding lookup: table[token_ids[i]] for each i.
/// table: [vocab_size, hidden_size], token_ids: [num_tokens] (i32 on CPU)
pub fn embedding(table: &Tensor, token_ids: &[u32]) -> Tensor {
assert_eq!(table.ndim(), 2);
assert!(table.is_contiguous());
assert!(matches!(table.device(), Device::Cuda(_)));
let hidden_size = table.shape()[1];
let num_tokens = token_ids.len();
let vocab_size = table.shape()[0];
assert!(
num_tokens <= i32::MAX as usize,
"too many tokens for i32 kernel param"
);
assert!(
hidden_size <= i32::MAX as usize,
"hidden_size too large for i32 kernel param"
);
// Upload token_ids to GPU
let ids_bytes = unsafe {
std::slice::from_raw_parts(
token_ids.as_ptr() as *const u8,
num_tokens * std::mem::size_of::<u32>(),
)
};
let mut ids_gpu =
xserv_cuda::allocator::cached_alloc(ids_bytes.len()).expect("alloc token_ids");
ids_gpu.copy_from_host(ids_bytes).unwrap();
for &tid in token_ids {
assert!(
(tid as usize) < vocab_size,
"token_id {tid} out of bounds (vocab_size={vocab_size})"
);
}
embedding_device_ids(table, ids_gpu.as_ptr() as *const c_void, num_tokens)
}
/// Embedding lookup with token ids already on the GPU (u32, [num_tokens]).
/// Used by the CUDA-graph decode path, where ids live in a persistent device
/// buffer updated outside the captured region (no bounds check possible here).
pub fn embedding_device_ids(table: &Tensor, ids_gpu: *const c_void, num_tokens: usize) -> Tensor {
assert_eq!(table.ndim(), 2);
assert!(table.is_contiguous());
assert!(matches!(table.device(), Device::Cuda(_)));
let hidden_size = table.shape()[1];
let vocab_size = table.shape()[0];
let out = Tensor::empty(&[num_tokens, hidden_size], table.dtype(), table.device());
unsafe {
match table.dtype() {
DType::F32 => launch_embedding_f32(
table.data_ptr() as _,
ids_gpu,
out.data_ptr() as *mut c_void,
num_tokens as i32,
hidden_size as i32,
vocab_size as i32,
xserv_cuda::current_stream_raw(),
),
DType::BF16 => launch_embedding_bf16(
table.data_ptr() as _,
ids_gpu,
out.data_ptr() as *mut c_void,
num_tokens as i32,
hidden_size as i32,
vocab_size as i32,
xserv_cuda::current_stream_raw(),
),
_ => panic!("unsupported dtype for embedding"),
}
}
out
}