Move config/util to AllocatorConfig for cross-allocator sharing

guangyey · guangyey · commit a2cbc94cf139 · 2025-07-31T15:18:29.000Z
ghstack-source-id: 52749a1 Pull Request resolved: #159553
diff --git a/c10/core/AllocatorConfig.h b/c10/core/AllocatorConfig.h
@@ -13,7 +13,17 @@
 namespace c10::CachingAllocator {
 
 // "large" allocations may be packed in 20 MiB blocks
-const size_t kLargeBuffer = 20971520;
+constexpr size_t kLargeBuffer = 20971520;
+// "small" allocations are packed in 2 MiB blocks
+constexpr size_t kSmallBuffer = 2097152;
+// all sizes are rounded to at least 512 bytes
+constexpr size_t kMinBlockSize = 512;
+// largest "small" allocation is 1 MiB
+constexpr size_t kSmallSize = 1048576;
+// allocations between 1 and 10 MiB may use kLargeBuffer
+constexpr size_t kMinLargeAlloc = 10485760;
+// round up large allocations to 2 MiB
+constexpr size_t kRoundLarge = 2097152;
 
 // A utility class for tokenizing allocator configuration strings into discrete
 // parts. For example, the config string:
@@ -369,4 +379,43 @@ struct DeviceConfigParserHookRegistry {
           parser_cls::getKeys());                             \
   }
 
+// This function takes the size and number of divisions argument and rounds
+// up the size argument for the nearest power-of-2 division.
+// For example, if we need to round-up 1200 and number of divisions is 4,
+// the size 1200 lies between 1024 and 2048 and if we do 4 divisions between
+// them, the values are 1024, 1280, 1536, and 1792. So the function will
+// return 1280 as the nearest ceiling of power-2 division.
+inline size_t roundup_power2_next_division(size_t size, size_t divisions) {
+  if (llvm::isPowerOf2_64(size)) {
+    return size;
+  }
+
+  TORCH_CHECK(divisions >= 2, "Only 2 or more divisions are supported");
+
+  // divide the space between these 2's power into equal divisions
+  // If division is zero, return the power-of-2 ceiling.
+  size_t power2_floor = llvm::PowerOf2Floor(size);
+  // power2_divison is the division size between power2_floor and power2_floor*2
+  size_t power2_divison =
+      power2_floor >> (63 - llvm::countLeadingZeros(divisions));
+  if (C10_UNLIKELY(power2_divison == 0)) {
+    return (power2_floor << 1);
+  }
+  size_t round_size_floor = size & (~(power2_divison - 1));
+  return (round_size_floor == size) ? size : round_size_floor + power2_divison;
+}
+
+inline size_t round_size(size_t size) {
+  if (size < kMinBlockSize) {
+    return kMinBlockSize;
+  } else {
+    auto divisions = AcceleratorAllocatorConfig::roundup_power2_divisions(size);
+    if (divisions > 1 && size > (kMinBlockSize * divisions)) {
+      return roundup_power2_next_division(size, divisions);
+    } else {
+      return kMinBlockSize * ((size + kMinBlockSize - 1) / kMinBlockSize);
+    }
+  }
+}
+
 } // namespace c10::CachingAllocator
diff --git a/c10/cuda/CUDACachingAllocator.cpp b/c10/cuda/CUDACachingAllocator.cpp
@@ -130,15 +130,6 @@ namespace Native {
  *                  notifyCaptureDestroy.
  */
 
-constexpr size_t kMinBlockSize =
-    512; // all sizes are rounded to at least 512 bytes
-constexpr size_t kSmallSize = 1048576; // largest "small" allocation is 1 MiB
-constexpr size_t kSmallBuffer =
-    2097152; // "small" allocations are packed in 2 MiB blocks
-constexpr size_t kMinLargeAlloc =
-    10485760; // allocations between 1 and 10 MiB may use kLargeBuffer
-constexpr size_t kRoundLarge = 2097152; // round up large allocations to 2 MiB
-
 static char SHAREABLE_HANDLE_VERSION = 2;
 enum ShareableHandleType : char {
   SHAREABLE_CUDA_MALLOC = 'c',
@@ -1332,7 +1323,7 @@ class DeviceCachingAllocator {
       //    effect on memory use during capture should be small.
       process_events(context);
     }
-    size_t size = round_size(orig_size);
+    size_t size = c10::CachingAllocator::round_size(orig_size);
     auto& pool = get_pool(size, stream);
     const size_t alloc_size = get_allocation_size(size);
     AllocParams params(device, size, stream, &pool, alloc_size);
@@ -2173,46 +2164,6 @@ class DeviceCachingAllocator {
     return result;
   }
 
-  // This function takes the size and number of divisions argument and rounds
-  // up the size argument for the nearest power-of-2 division.
-  // For example, if we need to round-up 1200 and number of divisions is 4,
-  // the size 1200 lies between 1024 and 2048 and if we do 4 divisions between
-  // them, the values are 1024, 1280, 1536, and 1792. So the function will
-  // return 1280 as the nearest ceiling of power-2 division.
-  static size_t roundup_power2_next_division(size_t size, size_t divisions) {
-    if (llvm::isPowerOf2_64(size)) {
-      return size;
-    }
-
-    TORCH_CHECK(divisions >= 2, "Only 2 or more divisions are supported");
-
-    // divide the space between these 2's power into equal divisions
-    // If division is zero, return the power-of-2 ceiling.
-    size_t power2_floor = llvm::PowerOf2Floor(size);
-    size_t power2_divison =
-        power2_floor >> (63 - llvm::countLeadingZeros(divisions));
-    if (C10_UNLIKELY(power2_divison == 0)) {
-      return (power2_floor << 1);
-    }
-    size_t round_size_floor = size & (~(power2_divison - 1));
-    return (round_size_floor == size) ? size
-                                      : round_size_floor + power2_divison;
-  }
-
-  static size_t round_size(size_t size) {
-    if (size < kMinBlockSize) {
-      return kMinBlockSize;
-    } else {
-      auto divisions =
-          AcceleratorAllocatorConfig::roundup_power2_divisions(size);
-      if (divisions > 1 && size > (kMinBlockSize * divisions)) {
-        return roundup_power2_next_division(size, divisions);
-      } else {
-        return kMinBlockSize * ((size + kMinBlockSize - 1) / kMinBlockSize);
-      }
-    }
-  }
-
   void createOrIncrefPool(MempoolId_t mempool_id, CUDAAllocator* allocator) {
     // Create a PrivatePool object if it does not exist yet
     // and increment its use_count
diff --git a/c10/xpu/XPUCachingAllocator.cpp b/c10/xpu/XPUCachingAllocator.cpp
@@ -15,16 +15,6 @@ using namespace c10::CachingDeviceAllocator;
 
 // newly allocated memory with 512-byte alignment.
 constexpr size_t kDeviceAlignment = 512;
-// all sizes are rounded to at least 512 bytes
-constexpr size_t kMinBlockSize = 512;
-// largest "small" allocation is 1 MiB
-constexpr size_t kSmallSize = 1048576;
-// "small" allocations are packed in 2 MiB blocks
-constexpr size_t kSmallBuffer = 2097152;
-// allocations between 1 and 10 MiB may use kLargeBuffer
-constexpr size_t kMinLargeAlloc = 10485760;
-// round up large allocations to 2 MiB
-constexpr size_t kRoundLarge = 2097152;
 
 namespace {
 using stream_set = ska::flat_hash_set<xpu::XPUStream>;
@@ -213,14 +203,6 @@ class DeviceCachingAllocator {
     }
   }
 
-  static size_t round_size(size_t size) {
-    if (size < kMinBlockSize) {
-      return kMinBlockSize;
-    } else {
-      return kMinBlockSize * ((size + kMinBlockSize - 1) / kMinBlockSize);
-    }
-  }
-
   static size_t get_allocation_size(size_t size) {
     if (size <= kSmallSize) {
       return kSmallBuffer;
@@ -417,7 +399,7 @@ class DeviceCachingAllocator {
   Block* malloc(DeviceIndex device, size_t orig_size, sycl::queue& queue) {
     std::scoped_lock<std::recursive_mutex> lock(mutex);
     process_events();
-    size_t size = round_size(orig_size);
+    size_t size = c10::CachingAllocator::round_size(orig_size);
     auto& pool = get_pool(size);
     const size_t alloc_size = get_allocation_size(size);
     AllocParams params(device, size, &queue, &pool, alloc_size);
