Bug 1683653 - Disable OMTP for users with less than 2 GB of virtual memory. r=jrmuizel

Also disable for users with 64-bit Firefox with 1-2 cores, and less than
2 GB of physical memory. It was already disabled for 32-bit Firefox.

Differential Revision: https://phabricator.services.mozilla.com/D101052

gfx/thebes/gfxPlatform.cpp

@@ -476,6 +476,8 @@ void gfxPlatform::OnMemoryPressure(layers::MemoryPressureReason aWhy) {
 
 gfxPlatform::gfxPlatform()
     : mHasVariationFontSupport(false),
+      mTotalPhysicalMemory(~0),
+      mTotalVirtualMemory(~0),
       mAzureCanvasBackendCollector(this, &gfxPlatform::GetAzureBackendInfo),
       mApzSupportCollector(this, &gfxPlatform::GetApzSupportInfo),
       mTilesInfoCollector(this, &gfxPlatform::GetTilesSupportInfo),
@@ -496,7 +498,16 @@ gfxPlatform::gfxPlatform()
 
   InitBackendPrefs(GetBackendPrefs());
 
-  mTotalSystemMemory = PR_GetPhysicalMemorySize();
+#ifdef XP_WIN
+  MEMORYSTATUSEX status;
+  status.dwLength = sizeof(status);
+  if (GlobalMemoryStatusEx(&status)) {
+    mTotalPhysicalMemory = status.ullTotalPhys;
+    mTotalVirtualMemory = status.ullTotalVirtual;
+  }
+#else
+  mTotalPhysicalMemory = PR_GetPhysicalMemorySize();
+#endif
 
   VRManager::ManagerInit();
 }
@@ -2901,18 +2912,20 @@ void gfxPlatform::InitOMTPConfig() {
                           Preferences::GetBool("layers.omtp.enabled", false,
                                                PrefValueKind::Default));
 
-  if (sizeof(void*) <= sizeof(uint32_t)) {
-    int32_t cpuCores = PR_GetNumberOfProcessors();
-    const uint64_t kMinSystemMemory = 2147483648;  // 2 GB
-    if (cpuCores <= 2) {
-      omtp.ForceDisable(FeatureStatus::Broken,
-                        "OMTP is not supported on 32-bit with <= 2 cores",
-                        "FEATURE_FAILURE_OMTP_32BIT_CORES"_ns);
-    } else if (mTotalSystemMemory < kMinSystemMemory) {
-      omtp.ForceDisable(FeatureStatus::Broken,
-                        "OMTP is not supported on 32-bit with < 2 GB RAM",
-                        "FEATURE_FAILURE_OMTP_32BIT_MEM"_ns);
-    }
+  int32_t cpuCores = PR_GetNumberOfProcessors();
+  const uint64_t kMinSystemMemory = 2147483648;  // 2 GB
+  if (cpuCores <= 2) {
+    omtp.ForceDisable(FeatureStatus::Broken,
+                      "OMTP is not supported with <= 2 cores",
+                      "FEATURE_FAILURE_OMTP_FEW_CORES"_ns);
+  } else if (mTotalPhysicalMemory < kMinSystemMemory) {
+    omtp.ForceDisable(FeatureStatus::Broken,
+                      "OMTP is not supported with < 2 GB RAM",
+                      "FEATURE_FAILURE_OMTP_LOW_PMEM"_ns);
+  } else if (mTotalVirtualMemory < kMinSystemMemory) {
+    omtp.ForceDisable(FeatureStatus::Broken,
+                      "OMTP is not supported with < 2 GB VMEM",
+                      "FEATURE_FAILURE_OMTP_LOW_VMEM"_ns);
   }
 
   if (mContentBackend == BackendType::CAIRO) {

gfx/thebes/gfxPlatform.h

@@ -931,7 +931,8 @@ class gfxPlatform : public mozilla::layers::MemoryPressureListener {
   // max number of entries in word cache
   int32_t mWordCacheMaxEntries;
 
-  uint64_t mTotalSystemMemory;
+  uint64_t mTotalPhysicalMemory;
+  uint64_t mTotalVirtualMemory;
 
   // Hardware vsync source. Only valid on parent process
   RefPtr<mozilla::gfx::VsyncSource> mVsyncSource;