Changeset 279922 in webkit

Timestamp:

Jul 14, 2021, 2:18:22 PM (5 years ago)

Author:

msaboff@apple.com

Message:

[BMalloc] Lazily allocate physical pages
​https://bugs.webkit.org/show_bug.cgi?id=227957

Reviewed by Mark Lam.

For the Darwin platform we don't need to call madvise(..., MADV_FREE_REUSE) to commit physical
memory to back a range of allocated virtual memory. Instead the kernel will commit pages
as they are touched. This can reduce the footprint of a process when there is sparse access
of allocated memory.

Also fixed a minor bug where we allocate memory, but don't update the amount of physical memory
associated with it.

• bmalloc/Heap.cpp:

(bmalloc::Heap::tryAllocateLargeChunk):

• bmalloc/VMAllocate.h:

(bmalloc::vmAllocatePhysicalPages):

Location:

trunk/Source/bmalloc

Files:

• ChangeLog (modified) (1 diff)
• bmalloc/Heap.cpp (modified) (1 diff)
• bmalloc/VMAllocate.h (modified) (1 diff)

trunk/Source/bmalloc/ChangeLog

@@ +1 @@
+2021-07-14  Michael Saboff  <msaboff@apple.com>
+
+        [BMalloc] Lazily allocate physical pages
+        https://bugs.webkit.org/show_bug.cgi?id=227957
+
+        Reviewed by Mark Lam.
+
+        For the Darwin platform we don't need to call madvise(..., MADV_FREE_REUSE) to commit physical
+        memory to back a range of allocated virtual memory.  Instead the kernel will commit pages
+        as they are touched.  This can reduce the footprint of a process when there is sparse access
+        of allocated memory.
+
+        Also fixed a minor bug where we allocate memory, but don't update the amount of physical memory
+        associated with it.
+
+        * bmalloc/Heap.cpp:
+        (bmalloc::Heap::tryAllocateLargeChunk):
+        * bmalloc/VMAllocate.h:
+        (bmalloc::vmAllocatePhysicalPages):
+
 2021-07-12  Filip Pizlo  <fpizlo@apple.com> and Yusuke Suzuki  <ysuzuki@apple.com>
 

trunk/Source/bmalloc/bmalloc/Heap.cpp

@@ -587 +587 @@
 #endif
 
-    return LargeRange(memory, size, 0, 0, memory);
+    return LargeRange(memory, size, size, size, static_cast<char*>(memory) + size);
 }
 

trunk/Source/bmalloc/bmalloc/VMAllocate.h

@@ -216 +216 @@
     vmValidatePhysical(p, vmSize);
 #if BOS(DARWIN)
-    SYSCALL(madvise(p, vmSize, MADV_FREE_REUSE));
+    BUNUSED_PARAM(p);
+    BUNUSED_PARAM(vmSize);
+    // For the Darwin platform, we don't need to call madvise(..., MADV_FREE_REUSE)
+    // to commit physical memory to back a range of allocated virtual memory.
+    // Instead the kernel will commit pages as they are touched.
 #else
     SYSCALL(madvise(p, vmSize, MADV_NORMAL));