[Experiment] purge-and-suspend

third_party/WebKit/Source/platform/heap/HeapPage.cpp

Index: third_party/WebKit/Source/platform/heap/HeapPage.cpp
diff --git a/third_party/WebKit/Source/platform/heap/HeapPage.cpp b/third_party/WebKit/Source/platform/heap/HeapPage.cpp
index b91b7597e8e65e34497e8eda1ad2a1fafbb62481..18b3c5d1e63344dd3e80cd8dc2ff502910dbd771 100644
--- a/third_party/WebKit/Source/platform/heap/HeapPage.cpp
+++ b/third_party/WebKit/Source/platform/heap/HeapPage.cpp
@@ -1201,10 +1201,7 @@ void NormalPage::sweep()
         if (startOfGap != headerAddress) {
             pageArena->addToFreeList(startOfGap, headerAddress - startOfGap);
 #if !ENABLE(ASSERT) && !defined(LEAK_SANITIZER) && !defined(ADDRESS_SANITIZER)
-            // Discarding pages increases page faults and may regress performance.
-            // So we enable this only on low-RAM devices.
-            if (ProcessHeap::isLowEndDevice())
-                discardPages(startOfGap + sizeof(FreeListEntry), headerAddress);
+            discardPages(startOfGap + sizeof(FreeListEntry), headerAddress);

[esprehn, 2016/08/05 23:00:58]

Why is it okay to remove the LowEndDevice comments and checks?

[tasak, 2016/08/08 04:47:36]

I don't want to remove the "if" and the comment. This is just for checking
whether the code affects resident_set_bytes or PSS or private_dirty or not.

I will revert the change when we are doing some experiment.
Instead, MemoryCoordinator will discard such unused pages if required.

 #endif
         }
         header->unmark();
@@ -1215,8 +1212,7 @@ void NormalPage::sweep()
     if (startOfGap != payloadEnd()) {
         pageArena->addToFreeList(startOfGap, payloadEnd() - startOfGap);
 #if !ENABLE(ASSERT) && !defined(LEAK_SANITIZER) && !defined(ADDRESS_SANITIZER)
-        if (ProcessHeap::isLowEndDevice())
-            discardPages(startOfGap + sizeof(FreeListEntry), payloadEnd());
+        discardPages(startOfGap + sizeof(FreeListEntry), payloadEnd());
 #endif
     }