Reduce maximum JIT pool size on X86_64.

Rubber stamped by Geoffrey Garen.

This changes our maximum pool size to 100MB. The problem with letting a page allocate much
more than this is that we will sometimes call deleteAllCode() or one of its friends. Deleting
a huge amount of memory is expensive in our allocator.

So long as we allow for such large-scale code death to happen, and so long as it's expensive,
we should bound the amount of code we end up with in the first place.

In the long run, we should fix our executable allocator so that it's not so expensive to kill
all code.

* jit/ExecutableAllocator.h:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@200481 268f45cc-cd09-0410-ab3c-d52691b4dbfc

diff --git a/Source/JavaScriptCore/ChangeLog b/Source/JavaScriptCore/ChangeLog
index 6130b31..d6b1266 100644 (file)
--- a/Source/JavaScriptCore/ChangeLog
+++ b/Source/JavaScriptCore/ChangeLog
@@ -1,5 +1,23 @@
 2016-05-05  Filip Pizlo  <fpizlo@apple.com>
 
+        Reduce maximum JIT pool size on X86_64.
+
+        Rubber stamped by Geoffrey Garen.
+        
+        This changes our maximum pool size to 100MB. The problem with letting a page allocate much
+        more than this is that we will sometimes call deleteAllCode() or one of its friends. Deleting
+        a huge amount of memory is expensive in our allocator.
+        
+        So long as we allow for such large-scale code death to happen, and so long as it's expensive,
+        we should bound the amount of code we end up with in the first place.
+        
+        In the long run, we should fix our executable allocator so that it's not so expensive to kill
+        all code.
+        
+        * jit/ExecutableAllocator.h:
+
+2016-05-05  Filip Pizlo  <fpizlo@apple.com>
+
         Reduce thresholds that control the maximum IC stub size.
 
         Rubber stamped by Chris Dumez and Benjamin Poulain.

diff --git a/Source/JavaScriptCore/jit/ExecutableAllocator.h b/Source/JavaScriptCore/jit/ExecutableAllocator.h
index 74cdc1f..081950e 100644 (file)
--- a/Source/JavaScriptCore/jit/ExecutableAllocator.h
+++ b/Source/JavaScriptCore/jit/ExecutableAllocator.h
@@ -79,7 +79,7 @@ static const size_t fixedExecutableMemoryPoolSize = 16 * 1024 * 1024;
 #elif CPU(ARM64)
 static const size_t fixedExecutableMemoryPoolSize = 32 * 1024 * 1024;
 #elif CPU(X86_64)
-static const size_t fixedExecutableMemoryPoolSize = 1024 * 1024 * 1024;
+static const size_t fixedExecutableMemoryPoolSize = 100 * 1024 * 1024;
 #else
 static const size_t fixedExecutableMemoryPoolSize = 32 * 1024 * 1024;
 #endif