Title: [86957] trunk/Source/_javascript_Core
- Revision
- 86957
- Author
- [email protected]
- Date
- 2011-05-20 08:55:16 -0700 (Fri, 20 May 2011)
Log Message
2011-05-20 Xan Lopez <[email protected]>
Reviewed by Oliver Hunt.
JIT requires VM overcommit (particularly on x86-64), Linux does not by default support this without swap?
https://bugs.webkit.org/show_bug.cgi?id=42756
Use the MAP_NORESERVE flag for mmap on Linux to skip the kernel
check of the available memory. This should give us an
overcommit-like behavior in most systems, which is what we want.
* wtf/OSAllocatorPosix.cpp:
(WTF::OSAllocator::reserveAndCommit): pass MAP_NORSERVE to mmap.
Modified Paths
Diff
Modified: trunk/Source/_javascript_Core/ChangeLog (86956 => 86957)
--- trunk/Source/_javascript_Core/ChangeLog 2011-05-20 15:50:55 UTC (rev 86956)
+++ trunk/Source/_javascript_Core/ChangeLog 2011-05-20 15:55:16 UTC (rev 86957)
@@ -1,3 +1,17 @@
+2011-05-20 Xan Lopez <[email protected]>
+
+ Reviewed by Oliver Hunt.
+
+ JIT requires VM overcommit (particularly on x86-64), Linux does not by default support this without swap?
+ https://bugs.webkit.org/show_bug.cgi?id=42756
+
+ Use the MAP_NORESERVE flag for mmap on Linux to skip the kernel
+ check of the available memory. This should give us an
+ overcommit-like behavior in most systems, which is what we want.
+
+ * wtf/OSAllocatorPosix.cpp:
+ (WTF::OSAllocator::reserveAndCommit): pass MAP_NORSERVE to mmap.
+
2011-05-19 Gabor Loki <[email protected]>
Fix ARM build after r86919
Modified: trunk/Source/_javascript_Core/wtf/OSAllocatorPosix.cpp (86956 => 86957)
--- trunk/Source/_javascript_Core/wtf/OSAllocatorPosix.cpp 2011-05-20 15:50:55 UTC (rev 86956)
+++ trunk/Source/_javascript_Core/wtf/OSAllocatorPosix.cpp 2011-05-20 15:55:16 UTC (rev 86957)
@@ -55,6 +55,18 @@
int flags = MAP_PRIVATE | MAP_ANON;
+#if OS(LINUX)
+ // Linux distros usually do not allow overcommit by default, so
+ // JSC's strategy of mmaping a large amount of memory upfront
+ // won't work very well on some systems. Fortunately there's a
+ // flag we can pass to mmap to disable the overcommit check for
+ // this particular call, so we can get away with it as long as the
+ // overcommit flag value in /proc/sys/vm/overcommit_memory is 0
+ // ('heuristic') and not 2 (always check). 0 is the usual default
+ // value, so this should work well in general.
+ flags |= MAP_NORESERVE;
+#endif
+
#if OS(DARWIN)
int fd = usage;
#else
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