add kvint8

csrc/attention/attention_kernels.cuh

@@ -33,6 +33,8 @@ typedef __hip_bfloat16 __nv_bfloat16;
   #include "../quantization/fp8/nvidia/quant_utils.cuh"
 #endif
 
+#include "../quantization/int8_kvcache/quant_utils.cuh"
+
 #ifndef USE_ROCM
   #define WARP_SIZE 32
 #else
@@ -280,6 +282,12 @@ __device__ void paged_attention_kernel(
         if constexpr (KV_DTYPE == Fp8KVCacheDataType::kAuto) {
           k_vecs[j] = *reinterpret_cast<const K_vec*>(
               k_ptr + offset1 * BLOCK_SIZE * x + offset2);
+        } else if constexpr (KV_DTYPE == Fp8KVCacheDataType::kInt8) {
+              Quant_vec k_vec_quant = *reinterpret_cast<const Quant_vec*>(
+                  k_ptr + offset1 * BLOCK_SIZE * x + offset2);
+              k_vecs[j] = int8::scaled_vec_conversion_int8<K_vec, Quant_vec>(
+                  k_vec_quant, 
+                  *k_scale);
         } else { 
           // Vector conversion from Quant_vec to K_vec.
           Quant_vec k_vec_quant = *reinterpret_cast<const Quant_vec*>(
@@ -410,6 +418,12 @@ __device__ void paged_attention_kernel(
 
         if constexpr (KV_DTYPE == Fp8KVCacheDataType::kAuto) {
           v_vec = *reinterpret_cast<const V_vec*>(v_ptr + offset);
+        } else if constexpr (KV_DTYPE == Fp8KVCacheDataType::kInt8) {
+          V_quant_vec v_quant_vec =
+              *reinterpret_cast<const V_quant_vec*>(v_ptr + offset);
+          // Vector conversion from V_quant_vec to V_vec.
+          v_vec = int8::scaled_vec_conversion_int8<V_vec, V_quant_vec>(v_quant_vec,
+                                                                       *v_scale);
         } else {
           V_quant_vec v_quant_vec =
               *reinterpret_cast<const V_quant_vec*>(v_ptr + offset);

csrc/attention/attention_kernels_opt.cu

@@ -14,6 +14,8 @@ typedef __hip_bfloat16 __nv_bfloat16;
   #include "../quantization/fp8/nvidia/quant_utils.cuh"
 #endif
 
+#include "../quantization/int8_kvcache/quant_utils.cuh"
+
 #ifndef USE_ROCM
   #define WARP_SIZE 32
 #else
@@ -311,6 +313,12 @@ __device__ void paged_attention_kernel_opt(
           if constexpr (KV_DTYPE == Fp8KVCacheDataType::kAuto) {
             k_vecs[j] = *reinterpret_cast<const K_vec*>(
                 k_ptr + offset1 * BLOCK_SIZE * x + offset2);
+          } else if constexpr (KV_DTYPE == Fp8KVCacheDataType::kInt8) {
+                Quant_vec k_vec_quant = *reinterpret_cast<const Quant_vec*>(
+                    k_ptr + offset1 * BLOCK_SIZE * x + offset2);
+                k_vecs[j] = int8::scaled_vec_conversion_int8<K_vec, Quant_vec>(
+                    k_vec_quant, 
+                    *k_scale_ptr);
           } else {
             // Vector conversion from Quant_vec to K_vec.
             Quant_vec k_vec_quant = *reinterpret_cast<const Quant_vec*>(
@@ -478,6 +486,13 @@ __device__ void paged_attention_kernel_opt(
 
         if constexpr (KV_DTYPE == Fp8KVCacheDataType::kAuto) {
           v_vec = *reinterpret_cast<const V_vec*>(v_ptr + offset);
+        } else if constexpr (KV_DTYPE == Fp8KVCacheDataType::kInt8) {
+          // printf("======xiabo_kvint8\n");
+          V_quant_vec v_quant_vec =
+              *reinterpret_cast<const V_quant_vec*>(v_ptr + offset);
+          // Vector conversion from V_quant_vec to V_vec.
+          v_vec = int8::scaled_vec_conversion_int8<V_vec, V_quant_vec>(v_quant_vec,
+                                                                       *v_scale_ptr);
         } else {
           V_quant_vec v_quant_vec =
               *reinterpret_cast<const V_quant_vec*>(v_ptr + offset);

csrc/attention/dtype_fp8.cuh

@@ -15,6 +15,7 @@ enum class Fp8KVCacheDataType {
   kAuto = 0,
   kFp8E4M3 = 1,
   kFp8E5M2 = 2,
+  kInt8 = 3,
 };
 
 // fp8 vector types for quantization of kv cache

csrc/cache_kernels.cu

@@ -12,6 +12,8 @@
   #include "quantization/fp8/nvidia/quant_utils.cuh"
 #endif
 
+#include "quantization/int8_kvcache/quant_utils.cuh"
+
 #include <algorithm>
 #include <cassert>
 #include <map>
@@ -252,6 +254,13 @@ __global__ void reshape_and_cache_kernel(
     if constexpr (kv_dt == Fp8KVCacheDataType::kAuto) {
       key_cache[tgt_key_idx] = tgt_key;
       value_cache[tgt_value_idx] = tgt_value;
+    } else if constexpr (kv_dt == Fp8KVCacheDataType::kInt8) {
+      key_cache[tgt_key_idx] =
+          int8::scaled_vec_conversion_int8<cache_t, scalar_t>(tgt_key, 
+                                                              *k_scale);
+      value_cache[tgt_value_idx] =
+          int8::scaled_vec_conversion_int8<cache_t, scalar_t>(tgt_value, 
+                                                              *v_scale);
     } else {
       key_cache[tgt_key_idx] =
           fp8::scaled_convert<cache_t, scalar_t, kv_dt>(tgt_key, *k_scale);
@@ -296,6 +305,13 @@ __global__ void reshape_and_cache_flash_kernel(
     if constexpr (kv_dt == Fp8KVCacheDataType::kAuto) {
       key_cache[tgt_key_value_idx] = tgt_key;
       value_cache[tgt_key_value_idx] = tgt_value;
+    } else if constexpr (kv_dt == Fp8KVCacheDataType::kInt8) {
+      key_cache[tgt_key_value_idx] =
+          int8::scaled_vec_conversion_int8<cache_t, scalar_t>(tgt_key, 
+                                                              *k_scale);
+      value_cache[tgt_key_value_idx] =
+          int8::scaled_vec_conversion_int8<cache_t, scalar_t>(tgt_value, 
+                                                              *v_scale);
     } else {
       key_cache[tgt_key_value_idx] =
           fp8::scaled_convert<cache_t, scalar_t, kv_dt>(tgt_key, *k_scale);

csrc/quantization/fp8/amd/quant_utils.cuh

@@ -653,6 +653,16 @@ __inline__ __device__ Tout scaled_convert(const Tin& x, const float scale) {
       } else {                                                                 \
         TORCH_CHECK(false, "Unsupported input type of kv cache: ", SRC_DTYPE); \
       }                                                                        \
+    } else if (KV_DTYPE == "int8") {                                           \
+      if (SRC_DTYPE == at::ScalarType::Float) {                                \
+        FN(float, uint8_t, vllm::Fp8KVCacheDataType::kInt8);                   \
+      } else if (SRC_DTYPE == at::ScalarType::Half) {                          \
+        FN(uint16_t, uint8_t, vllm::Fp8KVCacheDataType::kInt8);                \
+      } else if (SRC_DTYPE == at::ScalarType::BFloat16) {                      \
+        FN(__nv_bfloat16, uint8_t, vllm::Fp8KVCacheDataType::kInt8);           \
+      } else {                                                                 \
+        TORCH_CHECK(false,"Unsupported input type of kv cache: ", SRC_DTYPE);  \
+      }                                                                        \
     } else {                                                                   \
       if (KV_DTYPE == "fp8" || KV_DTYPE == "fp8_e4m3") {                       \
         if (SRC_DTYPE == at::ScalarType::Float) {                              \

csrc/quantization/int8_kvcache/quant_utils.cuh

+// Adated from FasterTransformer, https://github.com/NVIDIA/FasterTransformer/blob/release/v5.3_tag/src/fastertransformer/kernels/decoder_masked_multihead_attention/decoder_masked_multihead_attention_template.hpp
+#pragma once
+
+#include <assert.h>
+#include <stdint.h>
+#include <float.h>
+#include <type_traits>
+#include "../../attention/attention_dtypes.h"
+#include <stdio.h>
+
+namespace vllm {
+namespace int8 {
+
+
+// KV-CACHE int8
+static inline __device__ float int8_to_float(uint8_t x, const float scale) {
+  int8_t a = x - 128;
+  float res = a * scale;
+
+  return res;
+}
+
+static inline __device__ uint8_t float_to_int8(float x, const float scale) {
+  int8_t fx = roundf(max(-128.f, min(127.f, x / scale)));
+  uint8_t res = fx + 128;
+
+  return res;
+}
+
+template <typename Tout, typename Tin>
+__inline__ __device__ Tout scaled_vec_conversion_int8(const Tin& x,
+                                                      const float scale) {
+  return x;
+}
+
+// int8 -> half
+// template <>
+// __inline__ __device__ uint16_t scaled_vec_conversion_int8<uint16_t, uint8_t>(
+//     const uint8_t& a, const float scale) {
+//   float res = int8_to_float(a, scale);
+//   return float_to_half(res);
+//   // return half(a);__float2half 
+// }
+
+// int8x2 -> half2
+template <>
+__inline__ __device__ uint32_t scaled_vec_conversion_int8<uint32_t, uint16_t>(
+    const uint16_t& a, const float scale) {
+    union {
+        uint8_t  uint8[2];
+        uint16_t uint16;
+    };
+    uint16 = a;
+
+    float2 b;
+    b.x = (uint8[0] - 128) * scale;
+    b.y = (uint8[1] - 128) * scale;
+    union {
+        half2    float16;
+        uint32_t uint32;
+    };
+
+    float16 = __float22half2_rn(b);
+    return uint32;
+}
+
+template<typename Tout, typename Tin>
+__inline__ __device__ Tout vec_conversion(const Tin& x)
+{
+    return x;
+}
+template<>
+__inline__ __device__ uint32_t vec_conversion<uint32_t, float2>(const float2& a)
+{
+    union {
+        half2    float16;
+        uint32_t uint32;
+    };
+
+    float16 = __float22half2_rn(a);
+    return uint32;
+}
+
+template<>
+__inline__ __device__ uint2 vec_conversion<uint2, Float4_>(const Float4_& a)
+{
+    uint2  b;
+    float2 val;
+    val.x = a.x.x;
+    val.y = a.x.y;
+    b.x   = vec_conversion<uint32_t, float2>(val);
+
+    val.x = a.y.x;
+    val.y = a.y.y;
+    b.y   = vec_conversion<uint32_t, float2>(val);
+
+    return b;
+}
+// int8x4 -> half2x2
+template <>
+__inline__ __device__ uint2 scaled_vec_conversion_int8<uint2, uint32_t>(
+    const uint32_t& a, const float scale) {
+    union {
+        uint8_t  uint8[4];
+        uint32_t uint32;
+    };
+    uint32 = a;
+    Float4_ b;
+    b.x.x = (uint8[0] - 128) * scale;
+    b.x.y = (uint8[1] - 128) * scale;
+    b.y.x = (uint8[2] - 128) * scale;
+    b.y.y = (uint8[3] - 128) * scale;
+    return vec_conversion<uint2, Float4_>(b);
+}
+
+inline __device__ float2 dequant(uint16_t a, const float scale)
+{
+    union {
+        uint8_t  uint8[2];
+        uint16_t uint16;
+    };
+    uint16 = a;
+
+    float2 b;
+    b.x = (uint8[0] - 128) * scale;
+    b.y = (uint8[1] - 128) * scale;
+    return b;
+}
+
+// int8x8 -> half2x4
+template <>
+__inline__ __device__ uint4
+scaled_vec_conversion_int8<uint4, uint2>(const uint2& a, const float scale) {
+// scaled_vec_conversion_int8<uint4, uint64_t>(const uint64_t& a, const float scale) {
+
+    union {
+        uint16_t uint16[4];
+        uint2 uint64;
+    };
+    uint64 = a;
+
+    Float8_ b;
+    b.x = dequant(uint16[0], scale);
+    b.y = dequant(uint16[1], scale);
+    b.z = dequant(uint16[2], scale);
+    b.w = dequant(uint16[3], scale);
+    uint4 c;
+    c.x = vec_conversion<uint32_t, float2>(b.x);
+    c.y = vec_conversion<uint32_t, float2>(b.y);
+    c.z = vec_conversion<uint32_t, float2>(b.z);
+    c.w = vec_conversion<uint32_t, float2>(b.w);
+    return c;
+}
+
+// int8 -> __nv_bfloat16
+template <>
+__inline__ __device__ __nv_bfloat16
+scaled_vec_conversion_int8<__nv_bfloat16, uint8_t>(const uint8_t& a,
+                                                   const float scale) {
+  // Note there is no direct convert function from int8 to bf16.
+  float res = int8_to_float(a, scale);
+  return __float2bfloat16(res);
+}
+
+// int8x2 -> __nv_bfloat162
+template <>
+__inline__ __device__ __nv_bfloat162
+scaled_vec_conversion_int8<__nv_bfloat162, uint16_t>(const uint16_t& a,
+                                                     const float scale) {
+  __nv_bfloat162 res;
+  res.x = scaled_vec_conversion_int8<__nv_bfloat16, uint8_t>((uint8_t)a, scale);
+  res.y = scaled_vec_conversion_int8<__nv_bfloat16, uint8_t>((uint8_t)(a >> 8U),
+                                                             scale);
+  return res;
+}
+
+// int8x4 -> bf16_4_t
+template <>
+__inline__ __device__ bf16_4_t scaled_vec_conversion_int8<bf16_4_t, uint32_t>(
+    const uint32_t& a, const float scale) {
+  bf16_4_t res;
+  res.x =
+      scaled_vec_conversion_int8<__nv_bfloat162, uint16_t>((uint16_t)a, scale);
+  res.y = scaled_vec_conversion_int8<__nv_bfloat162, uint16_t>(
+      (uint16_t)(a >> 16U), scale);
+  return res;
+}
+
+// int8x8 -> bf16_8_t
+template <>
+__inline__ __device__ bf16_8_t
+scaled_vec_conversion_int8<bf16_8_t, uint2>(const uint2& a, const float scale) {
+// scaled_vec_conversion_int8<bf16_8_t, uint64_t>(const uint64_t& a, const float scale) {
+  // bf16_4_t tmp1, tmp2;
+  // tmp1 = scaled_vec_conversion_int8<bf16_4_t, uint32_t>(a.x, scale);
+  // tmp2 = scaled_vec_conversion_int8<bf16_4_t, uint32_t>(a.y, scale);
+  bf16_8_t res;
+  // res.x = tmp1.x;
+  // res.y = tmp1.y;
+  // res.z = tmp2.x;
+  // res.w = tmp2.y;
+  return res;
+}
+
+// int8 -> float
+template <>
+__inline__ __device__ float scaled_vec_conversion_int8<float, uint8_t>(
+    const uint8_t& a, const float scale) {
+  float res = int8_to_float(a, scale);
+  return res;
+}
+
+// int8x2 -> float2
+template <>
+__inline__ __device__ float2 scaled_vec_conversion_int8<float2, uint16_t>(
+    const uint16_t& a, const float scale) {
+  // int8x2 -> half2
+  uint32_t tmp = scaled_vec_conversion_int8<uint32_t, uint16_t>(a, scale);
+  // half2 -> float2
+  return half2_to_float2(tmp);
+}
+
+// int8x4 -> float4
+template <>
+__inline__ __device__ Float4_ scaled_vec_conversion_int8<Float4_, uint32_t>(
+    const uint32_t& a, const float scale) {
+  Float4_ res;
+  res.x = scaled_vec_conversion_int8<float2, uint16_t>((uint16_t)a, scale);
+  res.y =
+      scaled_vec_conversion_int8<float2, uint16_t>((uint16_t)(a >> 16U), scale);
+  return res;
+}
+
+// int8x8 -> float8
+template <>
+__inline__ __device__ Float8_
+scaled_vec_conversion_int8<Float8_, uint64_t>(const uint64_t& a, const float scale) {
+// scaled_vec_conversion_int8<Float8_, uint2>(const uint2& a, const float scale) {
+//   Float4_ tmp1, tmp2;
+//   tmp1 = scaled_vec_conversion_int8<Float4_, uint32_t>(a.x, scale);
+//   tmp2 = scaled_vec_conversion_int8<Float4_, uint32_t>(a.y, scale);
+  Float8_ res;
+//   res.x = tmp1.x;
+//   res.y = tmp1.y;
+//   res.z = tmp2.x;
+//   res.w = tmp2.y;
+  return res;
+}
+
+// half -> int8
+template <>
+__inline__ __device__ uint8_t scaled_vec_conversion_int8<uint8_t, uint16_t>(
+    const uint16_t& a, const float scale) {
+  uint8_t res = float_to_int8(half_to_float(a), scale);
+
+  return (uint8_t)res;
+  // return (uint8_t)(a);
+}
+
+// bf16 -> int8
+template <>
+__inline__ __device__ uint8_t
+scaled_vec_conversion_int8<uint8_t, __nv_bfloat16>(const __nv_bfloat16& a,
+                                                   const float scale) {
+  uint8_t res = float_to_int8(__bfloat162float(a), scale);
+  return (uint8_t)res;
+}
+
+// float -> int8
+template <>
+__inline__ __device__ uint8_t
+scaled_vec_conversion_int8<uint8_t, float>(const float& a, const float scale) {
+  uint8_t res = float_to_int8(a, scale);
+  return (uint8_t)res;
+  // return (uint8_t)(a);
+}
+
+// int8x4 -> float4
+template <>
+__inline__ __device__ float4 scaled_vec_conversion_int8<float4, uint32_t>(
+    const uint32_t& a, const float scale) {
+  Float4_ tmp = scaled_vec_conversion_int8<Float4_, uint32_t>(a, scale);
+  float4 res = make_float4(tmp.x.x, tmp.x.y, tmp.y.x, tmp.y.y);
+  return res;
+}
+
+} // namespace int8
+} // namespace vllm

vllm/attention/ops/paged_attn.py

@@ -131,7 +131,8 @@ class PagedAttention:
         # TODO(woosuk): Tune this heuristic.
         # For context len > 8192, use V2 kernel to avoid shared memory shortage.
         
-        
+        if (kv_cache_dtype == "int8"):
+            use_tc = False
         if use_tc and head_size==128:
             if envs.VLLM_USE_PA_PRINT_PARAM:
                 print("PA V1 SIZE:")

vllm/config.py

@@ -1288,7 +1288,7 @@ class ModelConfig:
 
 
 BlockSize = Literal[1, 8, 16, 32, 64, 128]
-CacheDType = Literal["auto", "fp8", "fp8_e4m3", "fp8_e5m2"]
+CacheDType = Literal["auto", "fp8", "fp8_e4m3", "fp8_e5m2", "int8"]
 PrefixCachingHashAlgo = Literal["builtin", "sha256"]
 
 

vllm/engine/arg_utils.py

@@ -1383,6 +1383,11 @@ class EngineArgs:
                 from vllm.attention.utils.fa_utils import (
                     flash_attn_supports_fp8)
                 supported = flash_attn_supports_fp8()
+
+            int8_attention = self.kv_cache_dtype.startswith("int8")
+            if int8_attention:
+                supported = True
+                
             if not supported:
                 _raise_or_fallback(feature_name="--kv-cache-dtype",
                                    recommend_to_remove=False)

vllm/utils.py

@@ -747,6 +747,8 @@ def get_kv_cache_torch_dtype(
             torch_dtype = STR_DTYPE_TO_TORCH_DTYPE[cache_dtype]
         elif cache_dtype == "fp8":
             torch_dtype = torch.uint8
+        elif cache_dtype == "int8":
+            torch_dtype = torch.uint8
         else:
             raise ValueError(f"Invalid kv cache dtype: {cache_dtype}")
     elif isinstance(cache_dtype, torch.dtype):
@@ -792,6 +794,8 @@ def create_kv_caches_with_random_flash(
             key_value_cache.uniform_(-scale, scale)
         elif cache_dtype == 'fp8':
             _generate_random_fp8(key_value_cache, -scale, scale)
+        elif cache_dtype == 'int8':
+            _generate_random_int8(value_cache)
         else:
             raise ValueError(
                 f"Does not support key cache of type {cache_dtype}")
@@ -833,6 +837,8 @@ def create_kv_caches_with_random(
             key_cache.uniform_(-scale, scale)
         elif cache_dtype == 'fp8':
             _generate_random_fp8(key_cache, -scale, scale)
+        elif cache_dtype == 'int8':
+            _generate_random_int8(key_value_cache)
         else:
             raise ValueError(
                 f"Does not support key cache of type {cache_dtype}")
@@ -848,6 +854,8 @@ def create_kv_caches_with_random(
             value_cache.uniform_(-scale, scale)
         elif cache_dtype == 'fp8':
             _generate_random_fp8(value_cache, -scale, scale)
+        elif cache_dtype == 'int8':
+            _generate_random_int8(key_cache)
         else:
             raise ValueError(
                 f"Does not support value cache of type {cache_dtype}")