[haiku-commits] r34934 - in haiku/trunk: headers/private/kernel/vm src/system/kernel/vm

From: ingo_weinhold@xxxxxx
To: haiku-commits@xxxxxxxxxxxxx
Date: Thu, 7 Jan 2010 15:09:56 +0100 (CET)
Author: bonefish
Date: 2010-01-07 15:09:56 +0100 (Thu, 07 Jan 2010)
New Revision: 34934
Changeset: http://dev.haiku-os.org/changeset/34934/haiku

Modified:
   haiku/trunk/headers/private/kernel/vm/VMAddressSpace.h
   haiku/trunk/src/system/kernel/vm/VMAddressSpace.cpp
Log:
VMAddressSpace::Put() is too hot to always write lock the address spaces
table. It is now inline and uses double-checked locking. This reduces the
contention on the lock to insignificant. Total -j8 Haiku image build speedup
is marginal, but the total kernel time drops 12%.


Modified: haiku/trunk/headers/private/kernel/vm/VMAddressSpace.h
===================================================================
--- haiku/trunk/headers/private/kernel/vm/VMAddressSpace.h      2010-01-07 
02:37:05 UTC (rev 34933)
+++ haiku/trunk/headers/private/kernel/vm/VMAddressSpace.h      2010-01-07 
14:09:56 UTC (rev 34934)
@@ -49,8 +49,8 @@
                        int32                           RefCount() const
                                                                        { 
return fRefCount; }
 
-                       void                            Get()   { 
atomic_add(&fRefCount, 1); }
-                       void                            Put();
+       inline  void                            Get()   { 
atomic_add(&fRefCount, 1); }
+       inline  void                            Put();
                        void                            RemoveAndPut();
 
                        void                            IncrementFaultCount()
@@ -107,6 +107,8 @@
        static  VMAddressSpace*         Get(team_id teamID);
 
 protected:
+       static  void                            _DeleteIfUnreferenced(team_id 
id);
+
        static  int                                     _DumpCommand(int argc, 
char** argv);
        static  int                                     _DumpListCommand(int 
argc, char** argv);
 
@@ -129,6 +131,15 @@
 };
 
 
+void
+VMAddressSpace::Put()
+{
+       team_id id = fID;
+       if (atomic_add(&fRefCount, -1) == 1)
+               _DeleteIfUnreferenced(id);
+}
+
+
 class VMAddressSpace::AreaIterator {
 public:
        AreaIterator()

Modified: haiku/trunk/src/system/kernel/vm/VMAddressSpace.cpp
===================================================================
--- haiku/trunk/src/system/kernel/vm/VMAddressSpace.cpp 2010-01-07 02:37:05 UTC 
(rev 34933)
+++ haiku/trunk/src/system/kernel/vm/VMAddressSpace.cpp 2010-01-07 14:09:56 UTC 
(rev 34934)
@@ -148,23 +148,6 @@
 }
 
 
-void
-VMAddressSpace::Put()
-{
-       bool remove = false;
-
-       rw_lock_write_lock(&sAddressSpaceTableLock);
-       if (atomic_add(&fRefCount, -1) == 1) {
-               sAddressSpaceTable.RemoveUnchecked(this);
-               remove = true;
-       }
-       rw_lock_write_unlock(&sAddressSpaceTableLock);
-
-       if (remove)
-               delete this;
-}
-
-
 /*! Deletes all areas in the specified address space, and the address
        space by decreasing all reference counters. It also marks the
        address space of being in deletion state, so that no more areas
@@ -293,6 +276,25 @@
 }
 
 
+/*static*/ void
+VMAddressSpace::_DeleteIfUnreferenced(team_id id)
+{
+       rw_lock_write_lock(&sAddressSpaceTableLock);
+
+       bool remove = false;
+       VMAddressSpace* addressSpace = sAddressSpaceTable.Lookup(id);
+       if (addressSpace != NULL && addressSpace->fRefCount == 0) {
+               sAddressSpaceTable.RemoveUnchecked(addressSpace);
+               remove = true;
+       }
+
+       rw_lock_write_unlock(&sAddressSpaceTableLock);
+
+       if (remove)
+               delete addressSpace;
+}
+
+
 /*static*/ int
 VMAddressSpace::_DumpCommand(int argc, char** argv)
 {
[haiku-commits] r34934 - in haiku/trunk: headers/private/kernel/vm src/system/kernel/vm

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