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Use StorageModePrivate for Metal PA kv cache #1506

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Merged
merged 1 commit into from
Jun 22, 2025
Merged

Use StorageModePrivate for Metal PA kv cache #1506

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12 changes: 6 additions & 6 deletions Cargo.lock
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8 changes: 4 additions & 4 deletions Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -27,10 +27,10 @@ license = "MIT"
rust-version = "1.82"

[workspace.dependencies]
candle-core = { git = "https://github.com/EricLBuehler/candle.git", version = "0.8.0", rev = "e8209f3" }
candle-nn = { git = "https://github.com/EricLBuehler/candle.git", version = "0.8.0", rev = "e8209f3" }
candle-flash-attn-v3 = { git = "https://github.com/EricLBuehler/candle.git", version = "0.8.0", rev = "e8209f3" }
candle-flash-attn = { git = "https://github.com/EricLBuehler/candle.git", version = "0.8.0", rev = "e8209f3" }
candle-core = { git = "https://github.com/EricLBuehler/candle.git", version = "0.8.0", rev = "98c0436e" }
candle-nn = { git = "https://github.com/EricLBuehler/candle.git", version = "0.8.0", rev = "98c0436e" }
candle-flash-attn-v3 = { git = "https://github.com/EricLBuehler/candle.git", version = "0.8.0", rev = "98c0436e" }
candle-flash-attn = { git = "https://github.com/EricLBuehler/candle.git", version = "0.8.0", rev = "98c0436e" }
# candle-core = { path = "../candle/candle-core" }
# candle-nn = { path = "../candle/candle-nn" }
# candle-flash-attn-v3 = { path = "../candle/candle-flash-attn-v3" }
Expand Down
108 changes: 84 additions & 24 deletions mistralrs-core/src/paged_attention/cache_engine.rs
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Expand Up @@ -3,7 +3,9 @@ use std::{
sync::{Arc, Mutex, MutexGuard},
};

use candle_core::{DType, Device, Result, Tensor};
use candle_core::{
from_storage_no_op, DType, Device, MetalStorage, Result, Shape, Storage, Tensor,
};
use mistralrs_paged_attn::{copy_blocks, swap_blocks};

use super::config::ModelConfigLike;
Expand Down Expand Up @@ -70,30 +72,88 @@ impl CacheEngine {
.take(model_config.num_layers())
.map(|x| x.as_ref().unwrap_or(device))
{
let key_blocks = unsafe {
Tensor::empty(
(
cache_config.num_gpu_blocks,
key_block_shape.0,
key_block_shape.1,
key_block_shape.2,
key_block_shape.3,
),
dtype,
device,
)?
let key_blocks = if let Device::Metal(dev) = &device {
#[cfg(feature = "metal")]
{
let elem_count = cache_config.num_gpu_blocks
* key_block_shape.0
* key_block_shape.1
* key_block_shape.2
* key_block_shape.3;
let buffer = dev.new_buffer_private(elem_count, dtype, "k_cache")?;
let storage =
Storage::Metal(MetalStorage::new(buffer, dev.clone(), elem_count, dtype));
from_storage_no_op(
storage,
Shape::from_dims(&[
cache_config.num_gpu_blocks,
key_block_shape.0,
key_block_shape.1,
key_block_shape.2,
key_block_shape.3,
]),
false,
)
}

#[cfg(not(feature = "metal"))]
{
unreachable!()
}
Comment on lines +99 to +102
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@coderabbitai coderabbitai bot Jun 22, 2025

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🛠️ Refactor suggestion

Consider graceful error handling instead of unreachable!().

Using unreachable!() when a Metal device is detected but the "metal" feature is not enabled could cause unexpected panics. Consider returning a proper error instead.

-#[cfg(not(feature = "metal"))]
-{
-    unreachable!()
-}
+#[cfg(not(feature = "metal"))]
+{
+    return Err(candle_core::Error::Msg(
+        "Metal device detected but metal feature not enabled".to_string()
+    ));
+}
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
#[cfg(not(feature = "metal"))]
{
unreachable!()
}
#[cfg(not(feature = "metal"))]
{
return Err(candle_core::Error::Msg(
"Metal device detected but metal feature not enabled".to_string()
));
}
🤖 Prompt for AI Agents 
In mistralrs-core/src/paged_attention/cache_engine.rs around lines 99 to 102,
replace the unreachable!() macro with graceful error handling by returning a
proper error indicating that the Metal feature is not enabled. This avoids
panics when a Metal device is detected but the "metal" feature is disabled,
improving robustness and error reporting.

} else {
unsafe {
Tensor::empty(
(
cache_config.num_gpu_blocks,
key_block_shape.0,
key_block_shape.1,
key_block_shape.2,
key_block_shape.3,
),
dtype,
device,
)?
}
};
let value_blocks = unsafe {
Tensor::empty(
(
cache_config.num_gpu_blocks,
value_block_shape.0,
value_block_shape.1,
value_block_shape.2,
),
dtype,
device,
)?
let value_blocks = if let Device::Metal(dev) = &device {
#[cfg(feature = "metal")]
{
let elem_count = cache_config.num_gpu_blocks
* value_block_shape.0
* value_block_shape.1
* value_block_shape.2;
let buffer = dev.new_buffer_private(elem_count, dtype, "v_cache")?;
let storage =
Storage::Metal(MetalStorage::new(buffer, dev.clone(), elem_count, dtype));
from_storage_no_op(
storage,
Shape::from_dims(&[
cache_config.num_gpu_blocks,
value_block_shape.0,
value_block_shape.1,
value_block_shape.2,
]),
false,
)
}

#[cfg(not(feature = "metal"))]
{
unreachable!()
}
} else {
unsafe {
Tensor::empty(
(
cache_config.num_gpu_blocks,
value_block_shape.0,
value_block_shape.1,
value_block_shape.2,
),
dtype,
device,
)?
}
};
gpu_cache.push((key_blocks, value_blocks));
}
Expand Down
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