From 2f24c4214ffc337f2c867e3981c33b16b3774bf4 Mon Sep 17 00:00:00 2001
From: gaaclarke <30870216+gaaclarke@users.noreply.github.com>
Date: Tue, 2 Jul 2024 11:32:12 -0700
Subject: [PATCH] [Impeller] fixed units for memory measurement
 (flutter/engine#53687)

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style
---
 .../flutter/impeller/renderer/backend/metal/allocator_mtl.mm   | 3 ++-
 .../impeller/renderer/backend/metal/allocator_mtl_unittests.mm | 2 +-
 .../flutter/impeller/renderer/backend/vulkan/allocator_vk.cc   | 2 +-
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/engine/src/flutter/impeller/renderer/backend/metal/allocator_mtl.mm b/engine/src/flutter/impeller/renderer/backend/metal/allocator_mtl.mm
index 913f733320..6a9e4437f4 100644
--- a/engine/src/flutter/impeller/renderer/backend/metal/allocator_mtl.mm
+++ b/engine/src/flutter/impeller/renderer/backend/metal/allocator_mtl.mm
@@ -99,7 +99,8 @@ void DebugAllocatorStats::Decrement(size_t size) {
 }
 
 size_t DebugAllocatorStats::GetAllocationSizeMB() {
-  size_t new_value = size_ / 1000000;
+  // RAM is measured in MiB, thus a divisor of 2^20 instead of 1,000,000.
+  size_t new_value = size_ / (1024 * 1024);
   return new_value;
 }
 
diff --git a/engine/src/flutter/impeller/renderer/backend/metal/allocator_mtl_unittests.mm b/engine/src/flutter/impeller/renderer/backend/metal/allocator_mtl_unittests.mm
index 4150caf20c..ea1bac5421 100644
--- a/engine/src/flutter/impeller/renderer/backend/metal/allocator_mtl_unittests.mm
+++ b/engine/src/flutter/impeller/renderer/backend/metal/allocator_mtl_unittests.mm
@@ -36,7 +36,7 @@ TEST_P(AllocatorMTLTest, DebugTraceMemoryStatistics) {
     TextureDescriptor desc;
     desc.format = PixelFormat::kR8G8B8A8UNormInt;
     desc.storage_mode = StorageMode::kDeviceTransient;
-    desc.size = {1000, 1000};
+    desc.size = {1024, 1024};
     auto texture_1 = allocator->CreateTexture(desc);
 
     EXPECT_EQ(allocator->DebugGetHeapUsage(), 0u);
diff --git a/engine/src/flutter/impeller/renderer/backend/vulkan/allocator_vk.cc b/engine/src/flutter/impeller/renderer/backend/vulkan/allocator_vk.cc
index 364b9aa49a..032f9d7e7d 100644
--- a/engine/src/flutter/impeller/renderer/backend/vulkan/allocator_vk.cc
+++ b/engine/src/flutter/impeller/renderer/backend/vulkan/allocator_vk.cc
@@ -519,7 +519,7 @@ size_t AllocatorVK::DebugGetHeapUsage() const {
     total_usage += budget.usage;
   }
   // Convert bytes to MB.
-  total_usage *= 1e-6;
+  total_usage /= (1024 * 1024);
   return total_usage;
 }