pa: enable tweaks that reduce calls to madvise/mprotect

Data looks good, so enabling by default. Only enabling on mac as mac benefits the most from this optimization (madvise/mprotect seem more expensive on mac, and we have to make double the number of them). Bug: 329199197 Change-Id: If35cee249658082de3b182070f43dd3fc045f552 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5598060 Reviewed-by: Benoit Lize <lizeb@chromium.org> Reviewed-by: Daniel Cheng <dcheng@chromium.org> Commit-Queue: Scott Violet <sky@chromium.org> Cr-Commit-Position: refs/heads/main@{#1310654}
blueboxd · Jun 17, 2024 · 1355520 · 1355520
1 parent 50a5e05
commit 1355520
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Showing 3 changed files with 13 additions and 18 deletions.
diff --git a/base/allocator/partition_alloc_features.cc b/base/allocator/partition_alloc_features.cc
@@ -108,7 +108,11 @@ MIRACLE_PARAMETER_FOR_INT(
 
 BASE_FEATURE(kPartitionAllocLargeEmptySlotSpanRing,
              "PartitionAllocLargeEmptySlotSpanRing",
+#if BUILDFLAG(IS_MAC)
+             FEATURE_ENABLED_BY_DEFAULT);
+#else
              FEATURE_DISABLED_BY_DEFAULT);
+#endif
 
 BASE_FEATURE(kPartitionAllocSchedulerLoopQuarantine,
              "PartitionAllocSchedulerLoopQuarantine",
@@ -486,7 +490,11 @@ void MakeFreeNoOp(WhenFreeBecomesNoOp callsite) {
 
 BASE_FEATURE(kPartitionAllocAdjustSizeWhenInForeground,
              "PartitionAllocAdjustSizeWhenInForeground",
-             base::FEATURE_DISABLED_BY_DEFAULT);
+#if BUILDFLAG(IS_MAC)
+             FEATURE_ENABLED_BY_DEFAULT);
+#else
+             FEATURE_DISABLED_BY_DEFAULT);
+#endif
 
 BASE_FEATURE(kPartitionAllocUseSmallSingleSlotSpans,
              "PartitionAllocUseSmallSingleSlotSpans",

diff --git a/testing/variations/fieldtrial_testing_config.json b/testing/variations/fieldtrial_testing_config.json
@@ -15032,23 +15032,6 @@
             ]
         }
     ],
-    "PartitionAllocParameterTuning": [
-        {
-            "platforms": [
-                "mac"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled_20240318",
-                    "enable_features": [
-                        "BlinkUseLargeEmptySlotSpanRingForBufferRoot",
-                        "PartitionAllocAdjustSizeWhenInForeground",
-                        "PartitionAllocLargeEmptySlotSpanRing"
-                    ]
-                }
-            ]
-        }
-    ],
     "PartitionAllocShortMemoryReclaim": [
         {
             "platforms": [

diff --git a/third_party/blink/renderer/platform/wtf/allocator/partitions.cc b/third_party/blink/renderer/platform/wtf/allocator/partitions.cc
@@ -55,7 +55,11 @@ const char* const Partitions::kAllocatedObjectPoolName =
 
 BASE_FEATURE(kBlinkUseLargeEmptySlotSpanRingForBufferRoot,
              "BlinkUseLargeEmptySlotSpanRingForBufferRoot",
+#if BUILDFLAG(IS_MAC)
+             base::FEATURE_ENABLED_BY_DEFAULT);
+#else
              base::FEATURE_DISABLED_BY_DEFAULT);
+#endif
 
 #if PA_BUILDFLAG(USE_STARSCAN)
 // Runs PCScan on WTF partitions.