Use the new rope kernel in mistral. (#1937)

* Use the new rope kernel in mistral.

* Compute the cos and sin with full precision.

* Bugfix.
This commit is contained in:
Laurent Mazare
2024-03-25 23:26:05 +01:00
committed by GitHub
parent 60676780a9
commit 196765e995
3 changed files with 14 additions and 30 deletions

View File

@ -88,13 +88,6 @@ struct RotaryEmbedding {
cos: Tensor,
}
fn rotate_half(xs: &Tensor) -> Result<Tensor> {
let last_dim = xs.dim(D::Minus1)?;
let xs1 = xs.narrow(D::Minus1, 0, last_dim / 2)?;
let xs2 = xs.narrow(D::Minus1, last_dim / 2, last_dim - last_dim / 2)?;
Tensor::cat(&[&xs2.neg()?, &xs1], D::Minus1)
}
impl RotaryEmbedding {
fn new(dtype: DType, cfg: &Config, dev: &Device) -> Result<Self> {
let rope_theta = cfg.rope_theta as f32;
@ -110,7 +103,6 @@ impl RotaryEmbedding {
.to_dtype(dtype)?
.reshape((max_seq_len, 1))?;
let freqs = t.matmul(&inv_freq)?;
let freqs = Tensor::cat(&[&freqs, &freqs], D::Minus1)?;
Ok(Self {
sin: freqs.sin()?,
cos: freqs.cos()?,
@ -126,10 +118,8 @@ impl RotaryEmbedding {
let (_b_sz, _h, seq_len, _n_embd) = q.dims4()?;
let cos = self.cos.narrow(0, seqlen_offset, seq_len)?;
let sin = self.sin.narrow(0, seqlen_offset, seq_len)?;
let cos = cos.unsqueeze(0)?.unsqueeze(0)?; // (1, 1, seq_len, dim)
let sin = sin.unsqueeze(0)?.unsqueeze(0)?; // (1, 1, seq_len, dim)
let q_embed = (q.broadcast_mul(&cos)? + rotate_half(q)?.broadcast_mul(&sin))?;
let k_embed = (k.broadcast_mul(&cos)? + rotate_half(k)?.broadcast_mul(&sin))?;
let q_embed = candle_nn::rotary_emb::rope(q, &cos, &sin)?;
let k_embed = candle_nn::rotary_emb::rope(k, &cos, &sin)?;
Ok((q_embed, k_embed))
}
}
@ -252,10 +242,12 @@ impl Attention {
let query_states = query_states
.reshape((b_sz, q_len, self.num_heads, self.head_dim))?
.transpose(1, 2)?;
.transpose(1, 2)?
.contiguous()?;
let key_states = key_states
.reshape((b_sz, q_len, self.num_kv_heads, self.head_dim))?
.transpose(1, 2)?;
.transpose(1, 2)?
.contiguous()?;
let value_states = value_states
.reshape((b_sz, q_len, self.num_kv_heads, self.head_dim))?
.transpose(1, 2)?;