Use cat for faster MQA computation. (#2043)

* Use cat for faster MQA computation.

* Move the function to utils + use it in mistral.

* Use the shared repeat-kv in a few more models.

* Fix.
This commit is contained in:
Laurent Mazare
2024-04-12 09:15:10 +02:00
committed by GitHub
parent a0460cd2b1
commit 3ad4770eb6
16 changed files with 47 additions and 195 deletions

View File

@ -191,18 +191,6 @@ impl Attention {
})
}
fn repeat_kv(&self, xs: Tensor) -> Result<Tensor> {
let n_rep = self.num_kv_groups;
if n_rep == 1 {
Ok(xs)
} else {
let (b_sz, num_kv_heads, seq_len, head_dim) = xs.dims4()?;
xs.unsqueeze(2)?
.expand((b_sz, num_kv_heads, n_rep, seq_len, head_dim))?
.reshape((b_sz, num_kv_heads * n_rep, seq_len, head_dim))
}
}
fn forward(
&mut self,
xs: &Tensor,
@ -239,8 +227,8 @@ impl Attention {
};
self.kv_cache = Some((key_states.clone(), value_states.clone()));
let key_states = self.repeat_kv(key_states)?.contiguous()?;
let value_states = self.repeat_kv(value_states)?.contiguous()?;
let key_states = crate::utils::repeat_kv(key_states, self.num_kv_groups)?;
let value_states = crate::utils::repeat_kv(value_states, self.num_kv_groups)?;
let attn_output = {
let scale = 1f64 / f64::sqrt(self.head_dim as f64);

View File

@ -256,17 +256,7 @@ impl CausalSelfAttention {
}
fn repeat_kv(&self, x: Tensor) -> Result<Tensor> {
let n_rep = self.num_attention_heads / self.num_key_value_heads;
if n_rep == 1 {
Ok(x)
} else {
let (b_sz, n_kv_head, seq_len, head_dim) = x.dims4()?;
let x = x
.unsqueeze(2)?
.expand((b_sz, n_kv_head, n_rep, seq_len, head_dim))?
.reshape((b_sz, n_kv_head * n_rep, seq_len, head_dim))?;
Ok(x)
}
crate::utils::repeat_kv(x, self.num_attention_heads / self.num_key_value_heads)
}
fn load(vb: VarBuilder, cfg: &Config) -> Result<Self> {

View File

@ -216,18 +216,6 @@ impl Attention {
})
}
fn repeat_kv(&self, xs: Tensor) -> Result<Tensor> {
let n_rep = self.num_kv_groups;
if n_rep == 1 {
Ok(xs)
} else {
let (b_sz, num_kv_heads, seq_len, head_dim) = xs.dims4()?;
xs.unsqueeze(2)?
.expand((b_sz, num_kv_heads, n_rep, seq_len, head_dim))?
.reshape((b_sz, num_kv_heads * n_rep, seq_len, head_dim))
}
}
fn forward(
&mut self,
xs: &Tensor,
@ -266,8 +254,8 @@ impl Attention {
};
self.kv_cache = Some((key_states.clone(), value_states.clone()));
let key_states = self.repeat_kv(key_states)?;
let value_states = self.repeat_kv(value_states)?;
let key_states = crate::utils::repeat_kv(key_states, self.num_kv_groups)?;
let value_states = crate::utils::repeat_kv(value_states, self.num_kv_groups)?;
let attn_output = if self.use_flash_attn {
// flash-attn expects (b_sz, seq_len, nheads, head_dim)

View File

@ -158,18 +158,6 @@ impl Attention {
})
}
fn repeat_kv(&self, xs: Tensor) -> Result<Tensor> {
let n_rep = self.num_kv_groups;
if n_rep == 1 {
Ok(xs)
} else {
let (b_sz, num_kv_heads, seq_len, head_dim) = xs.dims4()?;
xs.unsqueeze(2)?
.expand((b_sz, num_kv_heads, n_rep, seq_len, head_dim))?
.reshape((b_sz, num_kv_heads * n_rep, seq_len, head_dim))
}
}
fn forward(
&mut self,
xs: &Tensor,
@ -206,8 +194,8 @@ impl Attention {
};
self.kv_cache = Some((key_states.clone(), value_states.clone()));
let key_states = self.repeat_kv(key_states)?;
let value_states = self.repeat_kv(value_states)?;
let key_states = crate::utils::repeat_kv(key_states, self.num_kv_groups)?;
let value_states = crate::utils::repeat_kv(value_states, self.num_kv_groups)?;
let attn_output = if self.use_flash_attn {
// flash-attn expects (b_sz, seq_len, nheads, head_dim)

View File

@ -104,8 +104,8 @@ impl GroupedQueryAttention {
};
self.kv_cache = Some((key.clone(), value.clone()));
let query = query.contiguous()?;
let key = repeat_kv(key, self.n_heads / self.kv_n_heads)?.contiguous()?;
let value = repeat_kv(value, self.n_heads / self.kv_n_heads)?.contiguous()?;
let key = crate::utils::repeat_kv(key, self.n_heads / self.kv_n_heads)?.contiguous()?;
let value = crate::utils::repeat_kv(value, self.n_heads / self.kv_n_heads)?.contiguous()?;
let attn_weights = (query.matmul(&key)? * self.softmax_scale)?;
let attn_bias = {
let s_q = query.dim(D::Minus2)?;
@ -134,20 +134,6 @@ impl GroupedQueryAttention {
}
}
// This is the equivalent of torch.repeat_interleave(x, dim=1, repeats=n_rep).
// The hidden states go from (batch, num_key_value_heads, seqlen, head_dim) to
// (batch, num_attention_heads, seqlen, head_dim)
pub(crate) fn repeat_kv(xs: Tensor, n_rep: usize) -> Result<Tensor> {
if n_rep == 1 {
Ok(xs)
} else {
let (b_sz, num_kv_heads, seq_len, head_dim) = xs.dims4()?;
xs.unsqueeze(2)?
.expand((b_sz, num_kv_heads, n_rep, seq_len, head_dim))?
.reshape((b_sz, num_kv_heads * n_rep, seq_len, head_dim))
}
}
#[derive(Debug, Clone)]
struct Ffn {
up_proj: Linear,

View File

@ -174,15 +174,7 @@ impl Attention {
}
fn repeat_kv(&self, xs: Tensor) -> Result<Tensor> {
let n_rep = self.num_heads / self.num_kv_heads;
if n_rep == 1 {
Ok(xs)
} else {
let (b_sz, num_kv_heads, seq_len, head_dim) = xs.dims4()?;
xs.unsqueeze(2)?
.expand((b_sz, num_kv_heads, n_rep, seq_len, head_dim))?
.reshape((b_sz, num_kv_heads * n_rep, seq_len, head_dim))
}
crate::utils::repeat_kv(xs, self.num_heads / self.num_kv_heads)
}
fn forward(&mut self, xs: &Tensor, mask: Option<&Tensor>) -> Result<Tensor> {

View File

@ -205,9 +205,9 @@ impl LayerWeights {
};
self.kv_cache = Some((k.clone(), v.clone()));
// Support for MQA, useful for 70B models.
let k = self.repeat_kv(k)?;
let v = self.repeat_kv(v)?;
// Support for MQA, useful for 70B models and mistral.
let k = crate::utils::repeat_kv(k, self.n_head / self.n_kv_head)?;
let v = crate::utils::repeat_kv(v, self.n_head / self.n_kv_head)?;
let att = (q.matmul(&k.t()?)? / (self.head_dim as f64).sqrt())?;
let att = match mask {
@ -224,20 +224,6 @@ impl LayerWeights {
let y = self.attention_wo.forward(&y)?;
Ok(y)
}
fn repeat_kv(&self, x: Tensor) -> Result<Tensor> {
let n_rep = self.n_head / self.n_kv_head;
if n_rep == 1 {
Ok(x)
} else {
let (b_sz, n_kv_head, seq_len, head_dim) = x.dims4()?;
let x = x
.unsqueeze(2)?
.expand((b_sz, n_kv_head, n_rep, seq_len, head_dim))?
.reshape((b_sz, n_kv_head * n_rep, seq_len, head_dim))?;
Ok(x)
}
}
}
#[derive(Debug, Clone)]

View File

@ -122,18 +122,6 @@ impl Attention {
})
}
fn repeat_kv(&self, xs: Tensor) -> Result<Tensor> {
let n_rep = self.num_kv_groups;
if n_rep == 1 {
Ok(xs)
} else {
let (b_sz, num_kv_heads, seq_len, head_dim) = xs.dims4()?;
xs.unsqueeze(2)?
.expand((b_sz, num_kv_heads, n_rep, seq_len, head_dim))?
.reshape((b_sz, num_kv_heads * n_rep, seq_len, head_dim))
}
}
fn forward(
&mut self,
xs: &Tensor,
@ -172,8 +160,8 @@ impl Attention {
};
self.kv_cache = Some((key_states.clone(), value_states.clone()));
let key_states = self.repeat_kv(key_states)?;
let value_states = self.repeat_kv(value_states)?;
let key_states = crate::utils::repeat_kv(key_states, self.num_kv_groups)?;
let value_states = crate::utils::repeat_kv(value_states, self.num_kv_groups)?;
let attn_output = {
let scale = 1f64 / f64::sqrt(self.head_dim as f64);

View File

@ -71,8 +71,8 @@ impl GroupedQueryAttention {
};
self.kv_cache = Some((key.clone(), value.clone()));
let query = query.contiguous()?;
let key = super::mpt::repeat_kv(key, self.n_heads / self.kv_n_heads)?.contiguous()?;
let value = super::mpt::repeat_kv(value, self.n_heads / self.kv_n_heads)?.contiguous()?;
let key = crate::utils::repeat_kv(key, self.n_heads / self.kv_n_heads)?.contiguous()?;
let value = crate::utils::repeat_kv(value, self.n_heads / self.kv_n_heads)?.contiguous()?;
let attn_weights = (query.matmul(&key)? * self.softmax_scale)?;
let attn_bias = {
let s_q = query.dim(D::Minus2)?;

View File

@ -94,18 +94,6 @@ impl Attention {
})
}
fn repeat_kv(&self, xs: Tensor) -> Result<Tensor> {
let n_rep = self.num_kv_groups;
if n_rep == 1 {
Ok(xs)
} else {
let (b_sz, num_kv_heads, seq_len, head_dim) = xs.dims4()?;
xs.unsqueeze(2)?
.expand((b_sz, num_kv_heads, n_rep, seq_len, head_dim))?
.reshape((b_sz, num_kv_heads * n_rep, seq_len, head_dim))
}
}
fn forward(
&mut self,
xs: &Tensor,
@ -152,8 +140,9 @@ impl Attention {
self.kv_cache = Some((key_states.clone(), value_states.clone()));
}
let key_states = self.repeat_kv(key_states)?.contiguous()?;
let value_states = self.repeat_kv(value_states)?.contiguous()?;
let key_states = crate::utils::repeat_kv(key_states, self.num_kv_groups)?.contiguous()?;
let value_states =
crate::utils::repeat_kv(value_states, self.num_kv_groups)?.contiguous()?;
let attn_output = {
let scale = 1f64 / f64::sqrt(self.head_dim as f64);

View File

@ -146,18 +146,6 @@ impl Attention {
})
}
fn repeat_kv(&self, xs: Tensor) -> Result<Tensor> {
let n_rep = self.num_kv_groups;
if n_rep == 1 {
Ok(xs)
} else {
let (b_sz, num_kv_heads, seq_len, head_dim) = xs.dims4()?;
xs.unsqueeze(2)?
.expand((b_sz, num_kv_heads, n_rep, seq_len, head_dim))?
.reshape((b_sz, num_kv_heads * n_rep, seq_len, head_dim))
}
}
fn forward(
&mut self,
xs: &Tensor,
@ -194,8 +182,9 @@ impl Attention {
};
self.kv_cache = Some((key_states.clone(), value_states.clone()));
let key_states = self.repeat_kv(key_states)?.contiguous()?;
let value_states = self.repeat_kv(value_states)?.contiguous()?;
let key_states = crate::utils::repeat_kv(key_states, self.num_kv_groups)?.contiguous()?;
let value_states =
crate::utils::repeat_kv(value_states, self.num_kv_groups)?.contiguous()?;
let attn_output = {
let scale = 1f64 / f64::sqrt(self.head_dim as f64);

View File

@ -151,18 +151,6 @@ impl Attention {
})
}
fn repeat_kv(&self, xs: Tensor) -> Result<Tensor> {
let n_rep = self.num_kv_groups;
if n_rep == 1 {
Ok(xs)
} else {
let (b_sz, num_kv_heads, seq_len, head_dim) = xs.dims4()?;
xs.unsqueeze(2)?
.expand((b_sz, num_kv_heads, n_rep, seq_len, head_dim))?
.reshape((b_sz, num_kv_heads * n_rep, seq_len, head_dim))
}
}
fn forward(
&mut self,
xs: &Tensor,
@ -199,8 +187,9 @@ impl Attention {
};
self.kv_cache = Some((key_states.clone(), value_states.clone()));
let key_states = self.repeat_kv(key_states)?.contiguous()?;
let value_states = self.repeat_kv(value_states)?.contiguous()?;
let key_states = crate::utils::repeat_kv(key_states, self.num_kv_groups)?.contiguous()?;
let value_states =
crate::utils::repeat_kv(value_states, self.num_kv_groups)?.contiguous()?;
let attn_output = {
let scale = 1f64 / f64::sqrt(self.head_dim as f64);

View File

@ -217,18 +217,6 @@ impl Attention {
})
}
fn repeat_kv(&self, xs: Tensor) -> Result<Tensor> {
let n_rep = self.num_kv_groups;
if n_rep == 1 {
Ok(xs)
} else {
let (b_sz, num_kv_heads, seq_len, head_dim) = xs.dims4()?;
xs.unsqueeze(2)?
.expand((b_sz, num_kv_heads, n_rep, seq_len, head_dim))?
.reshape((b_sz, num_kv_heads * n_rep, seq_len, head_dim))
}
}
fn forward(
&mut self,
xs: &Tensor,
@ -275,8 +263,9 @@ impl Attention {
self.kv_cache = Some((key_states.clone(), value_states.clone()));
}
let key_states = self.repeat_kv(key_states)?.contiguous()?;
let value_states = self.repeat_kv(value_states)?.contiguous()?;
let key_states = crate::utils::repeat_kv(key_states, self.num_kv_groups)?.contiguous()?;
let value_states =
crate::utils::repeat_kv(value_states, self.num_kv_groups)?.contiguous()?;
let attn_output = if self.use_flash_attn {
// flash-attn expects (b_sz, seq_len, nheads, head_dim)

View File

@ -139,18 +139,6 @@ impl Attention {
})
}
fn repeat_kv(&self, xs: Tensor) -> Result<Tensor> {
let n_rep = self.num_kv_groups;
if n_rep == 1 {
Ok(xs)
} else {
let (b_sz, num_kv_heads, seq_len, head_dim) = xs.dims4()?;
xs.unsqueeze(2)?
.expand((b_sz, num_kv_heads, n_rep, seq_len, head_dim))?
.reshape((b_sz, num_kv_heads * n_rep, seq_len, head_dim))
}
}
fn forward(
&mut self,
xs: &Tensor,
@ -187,8 +175,8 @@ impl Attention {
};
self.kv_cache = Some((key_states.clone(), value_states.clone()));
let key_states = self.repeat_kv(key_states)?;
let value_states = self.repeat_kv(value_states)?;
let key_states = crate::utils::repeat_kv(key_states, self.num_kv_groups)?;
let value_states = crate::utils::repeat_kv(value_states, self.num_kv_groups)?;
let scale = 1f64 / f64::sqrt(self.head_dim as f64);
let attn_weights = (query_states.matmul(&key_states.transpose(2, 3)?)? * scale)?;

View File

@ -175,18 +175,6 @@ impl Attention {
})
}
fn repeat_kv(&self, xs: Tensor) -> Result<Tensor> {
let n_rep = self.num_kv_groups;
if n_rep == 1 {
Ok(xs)
} else {
let (b_sz, num_kv_heads, seq_len, head_dim) = xs.dims4()?;
xs.unsqueeze(2)?
.expand((b_sz, num_kv_heads, n_rep, seq_len, head_dim))?
.reshape((b_sz, num_kv_heads * n_rep, seq_len, head_dim))
}
}
fn forward(
&mut self,
xs: &Tensor,
@ -223,8 +211,8 @@ impl Attention {
};
self.kv_cache = Some((key_states.clone(), value_states.clone()));
let key_states = self.repeat_kv(key_states)?;
let value_states = self.repeat_kv(value_states)?;
let key_states = crate::utils::repeat_kv(key_states, self.num_kv_groups)?;
let value_states = crate::utils::repeat_kv(value_states, self.num_kv_groups)?;
let attn_output = {
let scale = 1f64 / f64::sqrt(self.head_dim as f64);

View File

@ -20,3 +20,17 @@ pub fn apply_repeat_penalty(logits: &Tensor, penalty: f32, context: &[u32]) -> R
let logits_len = logits.len();
Tensor::from_vec(logits, logits_len, device)
}
/// Repeats a key or value tensor for grouped query attention
/// The input tensor should have a shape `(batch, num_kv_heads, seq_len, head_dim)`,
pub fn repeat_kv(xs: Tensor, n_rep: usize) -> Result<Tensor> {
if n_rep == 1 {
Ok(xs)
} else {
let (b_sz, n_kv_head, seq_len, head_dim) = xs.dims4()?;
// Using cat is faster than a broadcast as it avoids going through a potentially
// strided copy.
// https://github.com/huggingface/candle/pull/2043
Tensor::cat(&vec![&xs; n_rep], 2)?.reshape((b_sz, n_kv_head * n_rep, seq_len, head_dim))
}
}