diff --git a/bindings/SigarWrapper.pm b/bindings/SigarWrapper.pm
index fd1be79f..b87068d0 100644
--- a/bindings/SigarWrapper.pm
+++ b/bindings/SigarWrapper.pm
@@ -94,6 +94,7 @@ my %has_name_arg = map { $_, 1 } qw(FileSystemUsage DiskUsage
                                     FileAttrs DirStat DirUsage
                                     NetInterfaceConfig NetInterfaceStat);
 
+
 my %proc_no_arg = map { $_, 1 } qw(stat);
 
 my %get_not_impl = map { $_, 1 } qw(net_address net_route net_connection net_stat cpu_perc
@@ -568,6 +569,7 @@ use vars qw(%classes %cmds);
          plat => '*'
       },
     ],
+
     ProcMem => [
       {
          name => 'size', type => 'Long',
@@ -668,6 +670,59 @@ use vars qw(%classes %cmds);
          plat => '*'
       },
     ],
+    ProcDiskIO => [
+      {
+         name => 'bytes_read', type => 'Long',
+         desc => 'Bytes Read',
+         plat => 'LW'
+      },
+      {
+         name => 'bytes_written', type => 'Long',
+         desc => 'Bytes Written',
+         plat => 'LW'
+      },
+      {
+         name => 'bytes_total', type => 'Long',
+         desc => 'Bytes Total',
+         plat => 'LWAHS'
+      }
+    ],
+
+    ProcCumulativeDiskIO => [
+      {
+         name => 'bytes_read', type => 'Long',
+         desc => 'Bytes Read from Start',
+         plat => 'LW'
+      },
+      {
+         name => 'bytes_written', type => 'Long',
+         desc => 'Bytes Written from Start',
+         plat => 'LW'
+      },
+      {
+         name => 'bytes_total', type => 'Long',
+         desc => 'Bytes Total from Start',
+         plat => 'LWAHS'
+      }
+    ],
+
+    DumpPidCache => [
+      {
+         name => 'dummy', type => 'Long',
+         desc => 'Dummy',
+         plat => 'LWAHS'
+      }
+    ],
+
+
+    DumpPidCache => [
+      {
+         name => 'dummy', type => 'Long',
+         desc => 'Dummy',
+         plat => 'LWAHS'
+      }
+    ],
+
     ProcState => [
       {
          name => 'state', type => 'Char',
diff --git a/bindings/java/src/org/hyperic/sigar/FileInfo.java b/bindings/java/src/org/hyperic/sigar/FileInfo.java
index 6e34fc24..bed90860 100644
--- a/bindings/java/src/org/hyperic/sigar/FileInfo.java
+++ b/bindings/java/src/org/hyperic/sigar/FileInfo.java
@@ -292,74 +292,58 @@ public class FileInfo extends FileAttrs implements java.io.Serializable {
     }
 
     public String diff(FileInfo info) {
-        ArrayList changes = new ArrayList();
+		ArrayList changes = new ArrayList();
 
-        if (this.getMtime() != info.getMtime()) {
-            changes.add(new Diff("Mtime",
-                                 formatDate(info.getMtime()),
-                                 formatDate(this.getMtime())));
+		if (this.getMtime() != info.getMtime()) {
+			changes.add(new Diff("Mtime", formatDate(info.getMtime()),
+					formatDate(this.getMtime())));
+		} else if (this.getCtime() != info.getCtime()) {
+			changes.add(new Diff("Ctime", formatDate(info.getCtime()),
+					formatDate(this.getCtime())));
+		}
+
+		if (this.getPermissions() != info.getPermissions()) {
+			changes.add(new Diff("Perms", info.getPermissionsString(), this
+					.getPermissionsString()));
+		}
+
+		if (this.getType() != info.getType()) {
+			changes.add(new Diff("Type", info.getTypeString(), this
+					.getTypeString()));
+		}
+
+		if (this.getUid() != info.getUid()) {
+			changes.add(new Diff("Uid", info.getUid(), this.getUid()));
+		}
+
+		if (this.getGid() != info.getGid()) {
+			changes.add(new Diff("Gid", info.getGid(), this.getGid()));
+		}
+
+		if (this.getSize() != info.getSize()) {
+			changes.add(new Diff("Size", info.getSize(), this.getSize()));
+		}
+
+		if (!OperatingSystem.IS_WIN32) {
+			if (this.getInode() != info.getInode()) {
+				changes.add(new Diff("Inode", info.getInode(), this.getInode()));
+			}
+
+			if (this.getDevice() != info.getDevice()) {
+				changes.add(new Diff("Device", info.getDevice(), this
+						.getDevice()));
+			}
+
+			if (this.getNlink() != info.getNlink()) {
+				changes.add(new Diff("Nlink", info.getNlink(), this.getNlink()));
+			}
         }
-        else if (this.getCtime() != info.getCtime()) {
-            changes.add(new Diff("Ctime",
-                                 formatDate(info.getCtime()),
-                                 formatDate(this.getCtime())));
-        }
-        else {
-            //no point in checking the rest if all times are the same.
-            //or should we include atime in the diff?
+
+        /* if changes were not detected then return empty String */
+        if (changes.isEmpty()){
             return "";
         }
-
-        if (this.getPermissions() != info.getPermissions()) {
-            changes.add(new Diff("Perms",
-                                 info.getPermissionsString(),
-                                 this.getPermissionsString()));
-        }
-
-        if (this.getType() != info.getType()) {
-            changes.add(new Diff("Type",
-                                 info.getTypeString(),
-                                 this.getTypeString()));
-        }
-
-        if (this.getUid() != info.getUid()) {
-            changes.add(new Diff("Uid",
-                                 info.getUid(),
-                                 this.getUid()));
-        }
-
-        if (this.getGid() != info.getGid()) {
-            changes.add(new Diff("Gid",
-                                 info.getGid(),
-                                 this.getGid()));
-        }
-
-        if (this.getSize() != info.getSize()) {
-            changes.add(new Diff("Size",
-                                 info.getSize(),
-                                 this.getSize()));
-        }
-
-        if (!OperatingSystem.IS_WIN32) {
-            if (this.getInode() != info.getInode()) {
-                changes.add(new Diff("Inode",
-                                     info.getInode(),
-                                     this.getInode()));
-            }
-
-            if (this.getDevice() != info.getDevice()) {
-                changes.add(new Diff("Device",
-                                     info.getDevice(),
-                                     this.getDevice()));
-            }
-
-            if (this.getNlink() != info.getNlink()) {
-                changes.add(new Diff("Nlink",
-                                     info.getNlink(),
-                                     this.getNlink()));
-            }
-        }
-
+        
         StringBuffer sb = format(changes);
         if (this.dirStatEnabled) {
             sb.append(diff(info.stat));
@@ -389,7 +373,9 @@ public class FileInfo extends FileAttrs implements java.io.Serializable {
 
         stat();
 
-        return this.mtime != oldInfo.mtime;
+        boolean isModified = isModified(this.oldInfo);
+        
+        return isModified;
     }
 
     public boolean changed()
@@ -455,4 +441,49 @@ public class FileInfo extends FileAttrs implements java.io.Serializable {
 
         return fetchInfo(sigar, name, false);
     }
+    
+    private boolean isModified(FileInfo info){
+    	/* Check modified time */
+		if (this.getMtime() != info.getMtime()) {
+			return true;
+		} else if (this.getCtime() != info.getCtime()) {
+			return true;
+		}
+		
+		if (this.getPermissions() != info.getPermissions()) {
+			return true;
+		}
+
+		if (this.getType() != info.getType()) {
+			return true;
+		}
+
+		if (this.getUid() != info.getUid()) {
+			return true;
+		}
+
+		if (this.getGid() != info.getGid()) {
+			return true;
+		}
+
+		if (this.getSize() != info.getSize()) {
+			return true;
+		}
+
+		if (!OperatingSystem.IS_WIN32) {
+			if (this.getInode() != info.getInode()) {
+				return true;
+			}
+
+			if (this.getDevice() != info.getDevice()) {
+				return true;
+			}
+
+			if (this.getNlink() != info.getNlink()) {
+				return true;
+			}
+		}
+
+		return false;
+	}
 }
diff --git a/bindings/java/src/org/hyperic/sigar/Sigar.java b/bindings/java/src/org/hyperic/sigar/Sigar.java
index 4abfb5b3..26995b66 100644
--- a/bindings/java/src/org/hyperic/sigar/Sigar.java
+++ b/bindings/java/src/org/hyperic/sigar/Sigar.java
@@ -41,6 +41,8 @@ public class Sigar implements SigarProxy {
     private static String loadError = null;
 
     public static final long FIELD_NOTIMPL = -1;
+    public static final int PID_PROC_CPU_CACHE = 1;
+    public static final int PID_PROC_IO_CACHE = 2;
 
     /**
      * The Sigar java version.
@@ -435,7 +437,7 @@ public class Sigar implements SigarProxy {
             return this.processFinder.findSingleProcess(pid);
         }
     }
-
+    
     /**
      * Get process memory info.
      * @param pid The process id.
@@ -633,6 +635,57 @@ public class Sigar implements SigarProxy {
                            Integer.parseInt(port));
     }
 
+    /**
+     * Get process disk IO info.
+     * @param pid THe process id.
+     * @exception SigarException on failure.
+     */
+    public ProcDiskIO getProcDiskIO(long pid) throws SigarException {
+    	try {
+    		return ProcDiskIO.fetch(this, pid);
+    	} catch (UnsatisfiedLinkError linkErrorException) {
+    		// We want to handle exceptions gracefully even if the linked
+    		// shared library is older and isn't compiled with the ProcDiskIO APIs.
+    		// The downside of this is that we throw SigarNotImplemented exception
+    		// also when the shared library can't be loaded.
+    		SigarException sigarException = new SigarNotImplementedException();
+    		sigarException.initCause(linkErrorException);
+    		throw sigarException;
+    	}
+    }
+
+    public ProcDiskIO getProcDiskIO(String pid) throws SigarException {
+    	return getProcDiskIO(convertPid(pid));
+    }
+
+   /**
+     * Get process cumulative disk IO info.
+     * @param pid THe process id.
+     * @exception SigarException on failure.
+     */
+    public ProcCumulativeDiskIO getProcCumulativeDiskIO(long pid) throws SigarException {
+        try {
+                return ProcCumulativeDiskIO.fetch(this, pid);
+        } catch (UnsatisfiedLinkError linkErrorException) {
+                // We want to handle exceptions gracefully even if the linked
+                // shared library is older and isn't compiled with the ProcDiskIO APIs.
+                // The downside of this is that we throw SigarNotImplemented exception
+                // also when the shared library can't be loaded.
+                SigarException sigarException = new SigarNotImplementedException();
+                sigarException.initCause(linkErrorException);
+                throw sigarException;
+        }
+    }
+
+  public ProcCumulativeDiskIO getProcCumulativeDiskIO(String pid) throws SigarException {
+        return getProcCumulativeDiskIO(convertPid(pid));
+  }
+
+  public DumpPidCache dumpPidCache() throws SigarException {
+       return DumpPidCache.fetch(this);
+  }
+
+
     /**
      * Get the cumulative cpu time for the calling thread.
      */
diff --git a/bindings/java/src/org/hyperic/sigar/SigarProxy.java b/bindings/java/src/org/hyperic/sigar/SigarProxy.java
index 7eba4386..151697b3 100644
--- a/bindings/java/src/org/hyperic/sigar/SigarProxy.java
+++ b/bindings/java/src/org/hyperic/sigar/SigarProxy.java
@@ -106,6 +106,16 @@ public interface SigarProxy {
 
     public long getProcPort(String protocol, String port) throws SigarException;
 
+    public ProcDiskIO getProcDiskIO(long pid) throws SigarException;
+
+    public ProcDiskIO getProcDiskIO(String pid) throws SigarException;
+
+    public ProcCumulativeDiskIO getProcCumulativeDiskIO(long pid) throws SigarException;
+
+    public ProcCumulativeDiskIO getProcCumulativeDiskIO(String pid) throws SigarException;
+
+    public DumpPidCache dumpPidCache() throws SigarException;
+
     public FileSystem[] getFileSystemList() throws SigarException;
 
     public FileSystemMap getFileSystemMap() throws SigarException;
diff --git a/bindings/java/src/org/hyperic/sigar/cmd/PidCacheInfo.java b/bindings/java/src/org/hyperic/sigar/cmd/PidCacheInfo.java
new file mode 100644
index 00000000..7404db3c
--- /dev/null
+++ b/bindings/java/src/org/hyperic/sigar/cmd/PidCacheInfo.java
@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2006-2007 Hyperic, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.hyperic.sigar.cmd;
+
+import org.hyperic.sigar.SigarException;
+import org.hyperic.sigar.SigarPermissionDeniedException;
+
+/**
+ * Display all pid cache information.
+ */
+public class PidCacheInfo extends SigarCommandBase {
+
+
+    public PidCacheInfo(Shell shell) {
+        super(shell);
+    }
+
+    public PidCacheInfo() {
+        super();
+    }
+
+    protected boolean validateArgs(String[] args) {
+        return true;
+    }
+
+    public String getUsageShort() {
+        return "Display cache info for CPU cache and for IO cache";
+    }
+
+    public boolean isPidCompleter() {
+        return false;
+    }
+
+    public void output(String[] args) throws SigarException {
+        sigar.dumpPidCache();
+    }
+}
diff --git a/bindings/java/src/org/hyperic/sigar/cmd/ProcInfo.java b/bindings/java/src/org/hyperic/sigar/cmd/ProcInfo.java
index e7614034..d68f9e75 100644
--- a/bindings/java/src/org/hyperic/sigar/cmd/ProcInfo.java
+++ b/bindings/java/src/org/hyperic/sigar/cmd/ProcInfo.java
@@ -100,6 +100,14 @@ public class ProcInfo extends SigarCommandBase {
         try {
             println("credname=" + sigar.getProcCredName(pid));
         } catch (SigarException e) {}
+        try {
+        	println("diskio=" + sigar.getProcDiskIO(pid));
+        } catch (SigarException e) {}
+
+ 	try {
+                println("cumulative diskio=" + sigar.getProcCumulativeDiskIO(pid));
+        } catch (SigarException e) {}
+
     }
 
     public static void main(String[] args) throws Exception {
diff --git a/bindings/java/src/org/hyperic/sigar/cmd/Shell.java b/bindings/java/src/org/hyperic/sigar/cmd/Shell.java
index 2e129163..c5b14b7f 100644
--- a/bindings/java/src/org/hyperic/sigar/cmd/Shell.java
+++ b/bindings/java/src/org/hyperic/sigar/cmd/Shell.java
@@ -102,6 +102,8 @@ public class Shell extends ShellBase {
         registerCommandHandler("time", new Time(this));
         registerCommandHandler("ulimit", new Ulimit(this));
         registerCommandHandler("who", new Who(this));
+        registerCommandHandler("pid_cache_info", new PidCacheInfo(this));
+
         if (SigarLoader.IS_WIN32) {
             registerCommandHandler("service", new Win32Service(this));
             registerCommandHandler("fversion", new FileVersionInfo(this));
diff --git a/bindings/java/src/org/hyperic/sigar/jmx/SigarProcess.java b/bindings/java/src/org/hyperic/sigar/jmx/SigarProcess.java
index 3d135d0b..0cd2e46f 100644
--- a/bindings/java/src/org/hyperic/sigar/jmx/SigarProcess.java
+++ b/bindings/java/src/org/hyperic/sigar/jmx/SigarProcess.java
@@ -19,6 +19,8 @@ package org.hyperic.sigar.jmx;
 import org.hyperic.sigar.ProcCpu;
 import org.hyperic.sigar.ProcFd;
 import org.hyperic.sigar.ProcMem;
+import org.hyperic.sigar.ProcUtil;
+import org.hyperic.sigar.ProcDiskIO;
 import org.hyperic.sigar.Sigar;
 import org.hyperic.sigar.SigarException;
 import org.hyperic.sigar.SigarProxy;
@@ -31,20 +33,24 @@ import org.hyperic.sigar.SigarProxyCache;
 
 public class SigarProcess implements SigarProcessMBean {
 
+    private static final Long NOTIMPL = new Long(Sigar.FIELD_NOTIMPL);
     private Sigar sigarImpl;
     private SigarProxy sigar;
+    private long pid = -1;
 
     public SigarProcess() {
-        this(new Sigar());
-    }
-
-    public SigarProcess(Sigar sigar) {
-        this.sigarImpl = sigar;
+        this.sigarImpl = new Sigar();
         this.sigar = SigarProxyCache.newInstance(sigarImpl);
     }
 
+    public SigarProcess(SigarProxy sigar) {
+        this.sigar = sigar;
+    }
+
     public void close() {
-        this.sigarImpl.close();
+        if (this.sigarImpl != null) {
+            this.sigarImpl.close();
+        }
     }
 
     private RuntimeException unexpectedError(String type,
@@ -57,8 +63,7 @@ public class SigarProcess implements SigarProcessMBean {
                                    
     private synchronized ProcMem getMem() {
         try {
-            long pid = this.sigar.getPid();
-            return this.sigar.getProcMem(pid);
+            return this.sigar.getProcMem(getPid());
         } catch (SigarException e) {
             throw unexpectedError("Mem", e);
         }
@@ -66,22 +71,40 @@ public class SigarProcess implements SigarProcessMBean {
 
     private synchronized ProcCpu getCpu() {
         try {
-            long pid = this.sigar.getPid();
-            return this.sigar.getProcCpu(pid);
+            return this.sigar.getProcCpu(getPid());
         } catch (SigarException e) {
             throw unexpectedError("Cpu", e);
         }   
     }
 
-    private synchronized ProcFd getFd() {
-        try {
-            long pid = this.sigar.getPid();
-            return this.sigar.getProcFd(pid);
+   
+    private synchronized ProcDiskIO getDiskIO() {
+	try {
+            return this.sigar.getProcDiskIO(getPid());
         } catch (SigarException e) {
-            throw unexpectedError("Fd", e);
-        }   
+            throw unexpectedError("DiskIO", e);
+        }
     }
-    
+
+
+    private synchronized ProcFd getFd() throws SigarException {
+        return this.sigar.getProcFd(getPid());
+    }
+
+
+    public long getPid() {
+        if (this.pid < 0) {
+            return this.sigar.getPid();
+        }
+        else {
+            return this.pid;
+        }
+    }
+
+    public void setPid(long pid) {
+        this.pid = pid;
+    }
+
     public Long getMemSize() {
         return new Long(getMem().getSize());
     }
@@ -119,7 +142,11 @@ public class SigarProcess implements SigarProcessMBean {
     }
 
     public Long getOpenFd() {
-        return new Long(getFd().getTotal());
+try {
+            return new Long(getFd().getTotal());
+        } catch (SigarException e) {
+            return NOTIMPL;
+        }    
     }
 
     public static void main(String args[]) {
@@ -132,4 +159,9 @@ public class SigarProcess implements SigarProcessMBean {
         System.out.println("TimeSys=" + proc.getTimeSys());
         System.out.println("OpenFd=" + proc.getOpenFd());
     }
+
+     public Double getBytesReadWriteTotal() {
+        return new Double(getDiskIO().getBytesTotal());
+    }
+
 }
diff --git a/bindings/java/src/org/hyperic/sigar/jmx/SigarProcessMBean.java b/bindings/java/src/org/hyperic/sigar/jmx/SigarProcessMBean.java
index d88d35e8..52b45488 100644
--- a/bindings/java/src/org/hyperic/sigar/jmx/SigarProcessMBean.java
+++ b/bindings/java/src/org/hyperic/sigar/jmx/SigarProcessMBean.java
@@ -44,4 +44,6 @@ public interface SigarProcessMBean {
     public Double getCpuUsage();
 
     public Long getOpenFd();
+    
+    public Double getBytesReadWriteTotal();
 }
diff --git a/bindings/java/src/org/hyperic/sigar/test/TestFileInfo.java b/bindings/java/src/org/hyperic/sigar/test/TestFileInfo.java
index 54150f0f..6e123923 100644
--- a/bindings/java/src/org/hyperic/sigar/test/TestFileInfo.java
+++ b/bindings/java/src/org/hyperic/sigar/test/TestFileInfo.java
@@ -133,11 +133,11 @@ public class TestFileInfo extends SigarTestCase {
         tmp.deleteOnExit();
         traceln("TMP=" + file);
 
-        try {
+      //  try {
             //stat() mtime is in seconds, this happens to quick to detect change.
-            Thread.sleep(1000 * 1);
-        } catch (InterruptedException e) {
-        }
+            //Thread.sleep(1000 * 1);
+      //  } catch (InterruptedException e) {
+       // }
 
         try {
             FileInfo info = sigar.getFileInfo(file);
diff --git a/bindings/java/src/org/hyperic/sigar/test/TestProcDiskIO.java b/bindings/java/src/org/hyperic/sigar/test/TestProcDiskIO.java
new file mode 100644
index 00000000..5148941e
--- /dev/null
+++ b/bindings/java/src/org/hyperic/sigar/test/TestProcDiskIO.java
@@ -0,0 +1,57 @@
+package org.hyperic.sigar.test;
+
+import org.hyperic.sigar.ProcDiskIO;
+import org.hyperic.sigar.Sigar;
+import org.hyperic.sigar.SigarException;
+
+public class TestProcDiskIO extends SigarTestCase {
+
+	public TestProcDiskIO(String name) {
+		super(name);
+	}
+	
+	
+    private void traceDiskIO(Sigar sigar, long pid) throws Exception {
+        ProcDiskIO procDiskIO;
+
+        try {
+            procDiskIO = sigar.getProcDiskIO(pid);
+        } catch (SigarException e) {
+            traceln("pid " + pid + ": " + e.getMessage());
+            // throw e;
+            return;
+        }
+
+        long bytesRead = procDiskIO.getBytesRead();
+        long bytesWritten = procDiskIO.getBytesWritten();
+        long bytesTotal = procDiskIO.getBytesTotal();
+        
+        traceln("Pid=" + pid);
+        traceln("Bytes Read=" + Sigar.formatSize(bytesRead));
+        traceln("Bytes Written=" + Sigar.formatSize(bytesWritten));
+        traceln("Bytes Total=" + Sigar.formatSize(bytesTotal));
+        
+        if (bytesRead != -1 && bytesWritten != -1 && bytesTotal != -1) {
+        	assertTrue("Bytes total should equal bytesRead + bytesWritten",
+        			    (bytesTotal == bytesRead + bytesWritten));
+        }
+    }
+
+    public void testCreate() throws Exception {
+        Sigar sigar = getSigar();
+
+        boolean caughtException = false;
+        try {
+            sigar.getProcDiskIO(getInvalidPid());
+        } catch (SigarException e) {
+        	caughtException = true;
+        }
+        assertTrue("Test on invalid PID should have thrown an exception.", caughtException);
+
+        long[] pids = sigar.getProcList();
+        for (int i=0; i<pids.length; i++) {
+            traceDiskIO(sigar, pids[i]);
+        }
+    }
+
+}
diff --git a/include/sigar.h b/include/sigar.h
index b8436373..d3e002d6 100644
--- a/include/sigar.h
+++ b/include/sigar.h
@@ -284,6 +284,47 @@ typedef struct {
 SIGAR_DECLARE(int) sigar_proc_mem_get(sigar_t *sigar, sigar_pid_t pid,
                                       sigar_proc_mem_t *procmem);
 
+typedef struct {
+     sigar_uint64_t 
+        bytes_read,
+        bytes_written,
+        bytes_total;
+} sigar_proc_disk_io_t;
+
+SIGAR_DECLARE(int) sigar_proc_disk_io_get(sigar_t *sigar, sigar_pid_t pid,
+                                          sigar_proc_disk_io_t *proc_disk_io);
+
+typedef struct {
+    sigar_uint64_t
+        bytes_read,
+        bytes_written,
+        bytes_total;
+    sigar_uint64_t last_time;
+    sigar_uint64_t
+        bytes_read_diff,
+        bytes_written_diff,
+        bytes_total_diff;
+} sigar_cached_proc_disk_io_t;
+
+
+typedef struct {
+    sigar_uint64_t
+        bytes_read,
+        bytes_written,
+        bytes_total;
+} sigar_proc_cumulative_disk_io_t;
+
+SIGAR_DECLARE(int) sigar_proc_cumulative_disk_io_get(sigar_t *sigar, sigar_pid_t pid,
+                                          sigar_proc_cumulative_disk_io_t *proc_cumulative_disk_io);
+
+
+typedef struct  { 
+    sigar_uint64_t dummy;
+}sigar_dump_pid_cache_t;
+
+SIGAR_DECLARE(int) sigar_dump_pid_cache_get(sigar_t *sigar, sigar_dump_pid_cache_t *info);
+
+
 typedef struct {
     sigar_uid_t uid;
     sigar_gid_t gid;
diff --git a/include/sigar_private.h b/include/sigar_private.h
index e242ed9e..6a91a958 100644
--- a/include/sigar_private.h
+++ b/include/sigar_private.h
@@ -66,7 +66,8 @@
    sigar_cache_t *proc_cpu; \
    sigar_cache_t *net_listen; \
    sigar_cache_t *net_services_tcp; \
-   sigar_cache_t *net_services_udp
+   sigar_cache_t *net_services_udp;\
+   sigar_cache_t *proc_io
 
 #if defined(WIN32)
 #   define SIGAR_INLINE __inline
@@ -339,11 +340,15 @@ int sigar_get_iftype(const char *name, int *type, int *inst);
 #define SIGAR_NIC_LOOPBACK "Local Loopback"
 #define SIGAR_NIC_ETHERNET "Ethernet"
 #define SIGAR_NIC_NETROM   "AMPR NET/ROM"
-
+#define PID_CACHE_CLEANUP_PERIOD 1000*60*10 /* 10 minutes */
+#define PID_CACHE_ENTRY_EXPIRE_PERIOD 1000*60*20 /* 20 minutes */
 #ifndef WIN32
 #include <netdb.h>
 #endif
 
+#define PROC_PID_CPU_CACHE 1
+#define PROC_PID_IO_CACHE 2
+
 #define SIGAR_HOSTENT_LEN 1024
 #if defined(_AIX)
 #define SIGAR_HAS_HOSTENT_DATA
diff --git a/include/sigar_util.h b/include/sigar_util.h
index bc605fc9..b3c4dd7d 100644
--- a/include/sigar_util.h
+++ b/include/sigar_util.h
@@ -170,15 +170,21 @@ struct sigar_cache_entry_t {
     sigar_cache_entry_t *next;
     sigar_uint64_t id;
     void *value;
+    sigar_uint64_t last_access_time;
 };
 
 typedef struct {
     sigar_cache_entry_t **entries;
     unsigned int count, size;
     void (*free_value)(void *ptr);
+    sigar_uint64_t entry_expire_period;
+    sigar_uint64_t cleanup_period_millis;
+    sigar_uint64_t last_cleanup_time;
 } sigar_cache_t;
 
 sigar_cache_t *sigar_cache_new(int size);
+sigar_cache_t *sigar_expired_cache_new(int size, sigar_uint64_t cleanup_period_millis, sigar_uint64_t entry_expire_period);
+void sigar_cache_dump(sigar_cache_t *table);
 
 sigar_cache_entry_t *sigar_cache_get(sigar_cache_t *table,
                                      sigar_uint64_t key);
diff --git a/src/os/aix/aix_sigar.c b/src/os/aix/aix_sigar.c
index 05b43730..17a09e60 100644
--- a/src/os/aix/aix_sigar.c
+++ b/src/os/aix/aix_sigar.c
@@ -745,6 +745,23 @@ int sigar_proc_mem_get(sigar_t *sigar, sigar_pid_t pid,
     return SIGAR_OK;
 }
 
+int sigar_proc_cumulative_disk_io_get(sigar_t *sigar, sigar_pid_t pid,
+                           sigar_proc_cumulative_disk_io_t *cumulative_proc_disk_io)
+{
+    int status = sigar_getprocs(sigar, pid);
+    struct procsinfo64 *pinfo = sigar->pinfo;
+
+    if (status != SIGAR_OK) {
+        return status;
+    }
+    cumulative_proc_disk_io->bytes_read = SIGAR_FIELD_NOTIMPL;
+    cumulative_proc_disk_io->bytes_written =  SIGAR_FIELD_NOTIMPL;
+    cumulative_proc_disk_io->bytes_total = pinfo->pi_ioch;
+
+    return SIGAR_OK;
+}
+
+
 int sigar_proc_cred_get(sigar_t *sigar, sigar_pid_t pid,
                         sigar_proc_cred_t *proccred)
 {
diff --git a/src/os/darwin/darwin_sigar.c b/src/os/darwin/darwin_sigar.c
index 7c0cd23f..148f3c1e 100644
--- a/src/os/darwin/darwin_sigar.c
+++ b/src/os/darwin/darwin_sigar.c
@@ -1241,6 +1241,13 @@ int sigar_proc_mem_get(sigar_t *sigar, sigar_pid_t pid,
     return SIGAR_OK;
 }
 
+int sigar_proc_cumulative_disk_io_get(sigar_t *sigar, sigar_pid_t pid,
+                           sigar_proc_cumulative_disk_io_t *proc_cumulative_disk_io)
+{
+    return SIGAR_ENOTIMPL;
+}
+
+
 int sigar_proc_cred_get(sigar_t *sigar, sigar_pid_t pid,
                         sigar_proc_cred_t *proccred)
 {
diff --git a/src/os/hpux/hpux_sigar.c b/src/os/hpux/hpux_sigar.c
index a419cca8..8761c1de 100644
--- a/src/os/hpux/hpux_sigar.c
+++ b/src/os/hpux/hpux_sigar.c
@@ -305,6 +305,25 @@ int sigar_proc_mem_get(sigar_t *sigar, sigar_pid_t pid,
     return SIGAR_OK;
 }
 
+int sigar_proc_cumulative_disk_io_get(sigar_t *sigar, sigar_pid_t pid, 
+                           sigar_proc_cumulative_disk_io_t *proc_cumulative_disk_io)
+{
+
+    int status = sigar_pstat_getproc(sigar, pid);
+    struct pst_status *pinfo = sigar->pinfo;
+
+    if (status != SIGAR_OK) {
+        return status;
+    }
+    proc_cumulative_disk_io->bytes_read = SIGAR_FIELD_NOTIMPL; 
+    proc_cumulative_disk_io->bytes_written = SIGAR_FIELD_NOTIMPL; 
+    proc_cumulative_disk_io->bytes_total =  pinfo->pst_ioch;
+
+
+   return SIGAR_OK;
+}
+
+
 int sigar_proc_cred_get(sigar_t *sigar, sigar_pid_t pid,
                         sigar_proc_cred_t *proccred)
 {
diff --git a/src/os/linux/linux_sigar.c b/src/os/linux/linux_sigar.c
index 0a446235..ef4bd046 100644
--- a/src/os/linux/linux_sigar.c
+++ b/src/os/linux/linux_sigar.c
@@ -767,6 +767,34 @@ int sigar_proc_mem_get(sigar_t *sigar, sigar_pid_t pid,
     return SIGAR_OK;
 }
 
+SIGAR_INLINE sigar_uint64_t get_named_proc_token(char *buffer,
+                                                 char *token) {
+  char *ptr = strstr(buffer, token);
+  if (!ptr) {
+    return SIGAR_FIELD_NOTIMPL;
+  }
+  ptr = sigar_skip_token(ptr);
+  return sigar_strtoul(ptr);
+}
+
+int sigar_proc_cumulative_disk_io_get(sigar_t *sigar, sigar_pid_t pid,
+                           sigar_proc_cumulative_disk_io_t *proc_cumulative_disk_io)
+{
+    char buffer[BUFSIZ];
+    
+    int status = SIGAR_PROC_FILE2STR(buffer, pid, "/io");
+    
+    if (status != SIGAR_OK) {
+        return status;
+    }
+
+    proc_cumulative_disk_io->bytes_read = get_named_proc_token(buffer, "\nread_bytes");
+    proc_cumulative_disk_io->bytes_written = get_named_proc_token(buffer, "\nwrite_bytes");
+    proc_cumulative_disk_io->bytes_total = proc_cumulative_disk_io->bytes_read + proc_cumulative_disk_io->bytes_written;
+
+    return SIGAR_OK;
+}
+
 #define NO_ID_MSG "[proc_cred] /proc/%lu" PROC_PSTATUS " missing "
 
 int sigar_proc_cred_get(sigar_t *sigar, sigar_pid_t pid,
diff --git a/src/os/solaris/solaris_sigar.c b/src/os/solaris/solaris_sigar.c
index 4d6a6106..17a4cfff 100644
--- a/src/os/solaris/solaris_sigar.c
+++ b/src/os/solaris/solaris_sigar.c
@@ -405,7 +405,7 @@ int sigar_cpu_get(sigar_t *sigar, sigar_cpu_t *cpu)
         cpu->idle  += xcpu->idle;
         cpu->nice  += xcpu->nice;
         cpu->wait  += xcpu->wait;
-        cpu->total = xcpu->total;
+        cpu->total += xcpu->total;
     }
 
     return SIGAR_OK;
@@ -717,6 +717,21 @@ int sigar_proc_mem_get(sigar_t *sigar, sigar_pid_t pid,
     return SIGAR_OK;
 }
 
+int sigar_proc_cumulative_disk_io_get(sigar_t *sigar, sigar_pid_t pid, 
+                           sigar_proc_cumulative_disk_io_t *proc_cumulative_disk_io)
+{
+   prusage_t usage;
+   int status;
+   if ((status = sigar_proc_usage_get(sigar, &usage, pid)) != SIGAR_OK) {
+        return status;
+   }
+   proc_cumulative_disk_io->bytes_read = SIGAR_FIELD_NOTIMPL;
+   proc_cumulative_disk_io->bytes_written = SIGAR_FIELD_NOTIMPL;
+   proc_cumulative_disk_io->bytes_total =  usage.pr_ioch;
+
+    return SIGAR_OK;
+}
+
 int sigar_proc_cred_get(sigar_t *sigar, sigar_pid_t pid,
                         sigar_proc_cred_t *proccred)
 {
diff --git a/src/os/win32/sigar_os.h b/src/os/win32/sigar_os.h
index 8eda061e..0f671584 100644
--- a/src/os/win32/sigar_os.h
+++ b/src/os/win32/sigar_os.h
@@ -317,6 +317,8 @@ typedef struct {
     sigar_uint64_t handles;
     sigar_uint64_t threads;
     sigar_uint64_t page_faults;
+	sigar_uint64_t bytes_read;
+	sigar_uint64_t bytes_written;
 } sigar_win32_pinfo_t;
 
 typedef struct {
diff --git a/src/os/win32/win32_sigar.c b/src/os/win32/win32_sigar.c
index 21277d79..c8a1d3f2 100755
--- a/src/os/win32/win32_sigar.c
+++ b/src/os/win32/win32_sigar.c
@@ -58,6 +58,8 @@ typedef enum {
 #define PERF_TITLE_PPID       1410
 #define PERF_TITLE_PRIORITY   682
 #define PERF_TITLE_START_TIME 684
+#define PERF_TITLE_IO_READ_BYTES_SEC	1420
+#define PERF_TITLE_IO_WRITE_BYTES_SEC	1422
 
 typedef enum {
     PERF_IX_CPUTIME,
@@ -70,6 +72,8 @@ typedef enum {
     PERF_IX_PPID,
     PERF_IX_PRIORITY,
     PERF_IX_START_TIME,
+	PERF_IX_IO_READ_BYTES_SEC,
+	PERF_IX_IO_WRITE_BYTES_SEC,
     PERF_IX_MAX
 } perf_proc_offsets_t;
 
@@ -1187,6 +1191,23 @@ SIGAR_DECLARE(int) sigar_proc_mem_get(sigar_t *sigar, sigar_pid_t pid,
     return SIGAR_OK;
 }
 
+SIGAR_DECLARE(int) sigar_proc_cumulative_disk_io_get(sigar_t *sigar, sigar_pid_t pid,
+                                          sigar_proc_cumulative_disk_io_t *proc_cumulative_disk_io)
+{
+    int status = get_proc_info(sigar, pid);
+    sigar_win32_pinfo_t *pinfo = &sigar->pinfo;
+
+    if (status != SIGAR_OK) {
+        return status;
+    }
+
+    proc_cumulative_disk_io->bytes_read = pinfo->bytes_read;
+    proc_cumulative_disk_io->bytes_written = pinfo->bytes_written;
+    proc_cumulative_disk_io->bytes_total = proc_cumulative_disk_io->bytes_read + proc_cumulative_disk_io->bytes_written;
+
+    return SIGAR_OK;
+}
+
 #define TOKEN_DAC (STANDARD_RIGHTS_READ | READ_CONTROL | TOKEN_QUERY)
 
 SIGAR_DECLARE(int)
@@ -1418,6 +1439,12 @@ static int get_proc_info(sigar_t *sigar, sigar_pid_t pid)
           case PERF_TITLE_START_TIME:
             perf_offsets[PERF_IX_START_TIME] = offset;
             break;
+		  case PERF_TITLE_IO_READ_BYTES_SEC:
+			perf_offsets[PERF_IX_IO_READ_BYTES_SEC] = offset;
+			break;
+		  case PERF_TITLE_IO_WRITE_BYTES_SEC:
+			perf_offsets[PERF_IX_IO_WRITE_BYTES_SEC] = offset;
+			break;
         }
     }
 
@@ -1443,6 +1470,8 @@ static int get_proc_info(sigar_t *sigar, sigar_pid_t pid)
         pinfo->handles  = PERF_VAL(PERF_IX_HANDLE_CNT);
         pinfo->threads  = PERF_VAL(PERF_IX_THREAD_CNT);
         pinfo->page_faults = PERF_VAL(PERF_IX_PAGE_FAULTS);
+		pinfo->bytes_read = PERF_VAL(PERF_IX_IO_READ_BYTES_SEC);
+		pinfo->bytes_written = PERF_VAL(PERF_IX_IO_WRITE_BYTES_SEC);
 
         return SIGAR_OK;
     }
@@ -3504,6 +3533,7 @@ int sigar_who_list_get_win32(sigar_t *sigar,
 #define SIGAR_ARCH "x86"
 #endif
 
+
 int sigar_os_sys_info_get(sigar_t *sigar,
                           sigar_sys_info_t *sysinfo)
 {
@@ -3511,7 +3541,7 @@ int sigar_os_sys_info_get(sigar_t *sigar,
     char *vendor_name, *vendor_version, *code_name=NULL;
 
     version.dwOSVersionInfoSize = sizeof(version);
-    GetVersionEx((OSVERSIONINFO *)&version);
+    GetVersionEx((OSVERSIONINFO *)&version); 
 
     if (version.dwMajorVersion == 4) {
         vendor_name = "Windows NT";
@@ -3551,11 +3581,25 @@ int sigar_os_sys_info_get(sigar_t *sigar,
                 code_name = "Vienna";
             }
         }
-        else {
-            vendor_name = "Windows 2008";
-            vendor_version = "2008";
-            code_name = "Longhorn Server";
-        }
+	else {
+             // not nt work station
+             if (version.dwMinorVersion == 0 || version.dwMinorVersion ==1) {
+            	vendor_name = "Windows 2008";
+            	vendor_version = "2008";
+	        code_name = "Longhorn Server";
+             }
+	     else  if (version.dwMinorVersion == 2) {
+ 	    	vendor_name = "Windows 2012";
+            	vendor_version = "2012";
+            	code_name = "Windows Server 8";
+	     }
+	     else {
+		// defaults
+		 vendor_name = "Windows Unknown";
+		 vendor_version = "2012";
+	     }
+	}
+
     }
 
     SIGAR_SSTRCPY(sysinfo->name, "Win32");
diff --git a/src/sigar.c b/src/sigar.c
index 1b8e4dd1..e0c8e7c1 100644
--- a/src/sigar.c
+++ b/src/sigar.c
@@ -59,6 +59,7 @@ SIGAR_DECLARE(int) sigar_open(sigar_t **sigar)
         (*sigar)->net_listen = NULL;
         (*sigar)->net_services_tcp = NULL;
         (*sigar)->net_services_udp = NULL;
+	(*sigar)->proc_io = NULL;
     }
 
     return status;
@@ -91,6 +92,11 @@ SIGAR_DECLARE(int) sigar_close(sigar_t *sigar)
     if (sigar->net_services_udp) {
         sigar_cache_destroy(sigar->net_services_udp);
     }
+    if (sigar->proc_io) {
+        sigar_cache_destroy(sigar->proc_io);
+    }
+
+
 
     return sigar_os_close(sigar);
 }
@@ -118,7 +124,7 @@ SIGAR_DECLARE(int) sigar_proc_cpu_get(sigar_t *sigar, sigar_pid_t pid,
     int status;
 
     if (!sigar->proc_cpu) {
-        sigar->proc_cpu = sigar_cache_new(128);
+        sigar->proc_cpu = sigar_expired_cache_new(128, PID_CACHE_CLEANUP_PERIOD, PID_CACHE_ENTRY_EXPIRE_PERIOD);
     }
 
     entry = sigar_cache_get(sigar->proc_cpu, pid);
@@ -167,6 +173,106 @@ SIGAR_DECLARE(int) sigar_proc_cpu_get(sigar_t *sigar, sigar_pid_t pid,
 
     return SIGAR_OK;
 }
+void copy_cached_disk_io_into_disk_io( sigar_cached_proc_disk_io_t *cached,  sigar_proc_disk_io_t *proc_disk_io) {
+   proc_disk_io->bytes_read = cached->bytes_read_diff;
+   proc_disk_io->bytes_written = cached->bytes_written_diff;
+   proc_disk_io->bytes_total = cached->bytes_total_diff;
+}
+
+sigar_uint64_t get_io_diff(sigar_uint64_t current_value, sigar_uint64_t prev_value,  sigar_uint64_t time_diff) {
+   double io_diff;
+   sigar_uint64_t int_io_diff;
+   if ( current_value == SIGAR_FIELD_NOTIMPL ) {
+      return SIGAR_FIELD_NOTIMPL;
+   }
+   io_diff = (( current_value - prev_value)/(double)time_diff)*SIGAR_MSEC;
+   int_io_diff = (sigar_uint64_t)io_diff;
+   if (int_io_diff >=0) {
+      return int_io_diff;
+   }
+   return 0;
+}
+
+void calculate_io_diff(sigar_proc_cumulative_disk_io_t * proc_disk_io, sigar_cached_proc_disk_io_t *cached,  sigar_uint64_t time_diff, int is_first_time) {
+   /*calculate avg diff /read/write/total per second*/
+   if (!is_first_time) {
+       cached->bytes_written_diff = get_io_diff(proc_disk_io->bytes_written, cached->bytes_written, time_diff);
+       cached->bytes_read_diff = get_io_diff(proc_disk_io->bytes_read, cached->bytes_read, time_diff);
+       cached->bytes_total_diff = get_io_diff(proc_disk_io->bytes_total, cached->bytes_total, time_diff);
+   }
+   else {
+       cached->bytes_total_diff =  cached->bytes_read_diff =  cached->bytes_written_diff = 0.0;
+   }
+   // now put in cache the current cumulative values
+   cached->bytes_written = proc_disk_io->bytes_written;
+   cached->bytes_read = proc_disk_io->bytes_read;
+   cached->bytes_total = proc_disk_io->bytes_total;
+}
+
+SIGAR_DECLARE(int) sigar_proc_disk_io_get(sigar_t *sigar, sigar_pid_t pid,
+                                          sigar_proc_disk_io_t *proc_disk_io)
+{
+    sigar_cache_entry_t *entry;
+    sigar_cached_proc_disk_io_t *prev;
+    sigar_proc_cumulative_disk_io_t  cumulative_proc_disk_io;
+    sigar_uint64_t time_now = sigar_time_now_millis();
+    sigar_uint64_t time_diff;
+    int status, is_first_time;
+
+    if (!sigar->proc_io) {
+        sigar->proc_io =  sigar_expired_cache_new(128, PID_CACHE_CLEANUP_PERIOD, PID_CACHE_ENTRY_EXPIRE_PERIOD);
+    }
+
+    entry = sigar_cache_get(sigar->proc_io, pid);
+    if (entry->value) {
+        prev = (sigar_cached_proc_disk_io_t *)entry->value;
+    }
+    else {
+        prev = entry->value = malloc(sizeof(*prev));
+        SIGAR_ZERO(prev);
+    }
+    is_first_time = (prev->last_time == 0);
+    time_diff = time_now - prev->last_time;
+
+    if (time_diff < 1000) {
+        /* we were just called within < 1 second ago. */
+        copy_cached_disk_io_into_disk_io(prev, proc_disk_io);
+	if (time_diff < 0) {
+	   // something is wrong at least from now on the time will be ok
+ 	   prev->last_time = time_now;
+        }
+        return SIGAR_OK;
+    }
+    prev->last_time = time_now;
+
+
+    status =
+        sigar_proc_cumulative_disk_io_get(sigar, pid,
+                            &cumulative_proc_disk_io);
+
+    if (status != SIGAR_OK) {
+        return status;
+    }
+    calculate_io_diff(&cumulative_proc_disk_io, prev, time_diff,  is_first_time);
+    copy_cached_disk_io_into_disk_io(prev, proc_disk_io);
+    return SIGAR_OK;
+}
+
+void get_cache_info(sigar_cache_t * cache, char * name){
+   if (cache == NULL) {
+      return;
+   }
+
+   printf("******** %s *********\n", name);
+   sigar_cache_dump(cache);
+}
+
+SIGAR_DECLARE(int) sigar_dump_pid_cache_get(sigar_t *sigar, sigar_dump_pid_cache_t *info) {
+  
+  get_cache_info(sigar->proc_cpu, "proc cpu cache");
+  get_cache_info(sigar->proc_io, "proc io cache");
+  return SIGAR_OK;
+}
 
 SIGAR_DECLARE(int) sigar_proc_stat_get(sigar_t *sigar,
                                        sigar_proc_stat_t *procstat)
diff --git a/src/sigar_cache.c b/src/sigar_cache.c
index 8d640167..5b158edc 100644
--- a/src/sigar_cache.c
+++ b/src/sigar_cache.c
@@ -35,7 +35,7 @@ static void free_value(void *ptr)
     free(ptr);
 }
 
-sigar_cache_t *sigar_cache_new(int size)
+sigar_cache_t *sigar_expired_cache_new(int size, sigar_uint64_t cleanup_period_millis, sigar_uint64_t entry_expire_period)
 {
     sigar_cache_t *table = malloc(sizeof(*table));
     table->count = 0;
@@ -43,16 +43,27 @@ sigar_cache_t *sigar_cache_new(int size)
     table->entries = malloc(ENTRIES_SIZE(size));
     memset(table->entries, '\0', ENTRIES_SIZE(size));
     table->free_value = free_value;
+    table->cleanup_period_millis = cleanup_period_millis;
+    table->last_cleanup_time = sigar_time_now_millis();
+    table->entry_expire_period = entry_expire_period;
     return table;
 }
 
-#ifdef DEBUG_CACHE
+sigar_cache_t *sigar_cache_new(int size)
+{
+    return sigar_expired_cache_new(size, SIGAR_FIELD_NOTIMPL, SIGAR_FIELD_NOTIMPL);
+}
+
+
+/*#ifdef DEBUG_CACHE*/
 /* see how well entries are distributed */
-static void sigar_cache_dump(sigar_cache_t *table)
+void sigar_cache_dump(sigar_cache_t *table)
 {
     int i;
     sigar_cache_entry_t **entries = table->entries;
-
+    printf("table size %lu\n", (long)table->size); 
+    printf("table count %lu\n", (long)table->count);
+    
     for (i=0; i<table->size; i++) {
         sigar_cache_entry_t *entry = *entries++;
 
@@ -68,12 +79,12 @@ static void sigar_cache_dump(sigar_cache_t *table)
     printf("\n");
     fflush(stdout);
 }
-#endif
+/*#endif*/
 
 static void sigar_cache_rehash(sigar_cache_t *table)
 {
     int i;
-    unsigned int new_size = table->size * 2 + 1;
+    unsigned int new_size = table->count * 2 + 1;
     sigar_cache_entry_t **entries = table->entries;
     sigar_cache_entry_t **new_entries =
         malloc(ENTRIES_SIZE(new_size));
@@ -101,16 +112,76 @@ static void sigar_cache_rehash(sigar_cache_t *table)
 #define SIGAR_CACHE_IX(t, k) \
     t->entries + (k % t->size)
 
+void sigar_perform_cleanup_if_necessary(sigar_cache_t *table) { 
+    sigar_uint64_t current_time;
+	int i;
+	sigar_cache_entry_t **entries;
+    if (table->cleanup_period_millis == SIGAR_FIELD_NOTIMPL) {
+		/* no cleanup for this cache) */
+		return;
+    }
+    current_time = sigar_time_now_millis();
+    if ((current_time - table->last_cleanup_time) < table->cleanup_period_millis) {
+        /* not enough time has passed since last cleanup */
+        return;
+    }	
+
+    /* performing cleanup */    
+    entries = table->entries;
+
+    table->last_cleanup_time = current_time;
+    
+    for (i=0; i<table->size; i++) {
+        sigar_cache_entry_t *entry, *ptr, *entry_prev=NULL, **entry_in_table;
+        entry_in_table = entries;
+        entry = *entries++;
+
+        while (entry) {
+			sigar_uint64_t period_with_no_access = current_time - entry->last_access_time;
+            ptr = entry->next;            
+            if (table->entry_expire_period < period_with_no_access) {
+		       /* no one acess this entry for too long - we can delete it */
+	           if (entry->value) {
+                   table->free_value(entry->value);
+                } 
+                free(entry);
+		        table->count--;
+                if (entry_prev != NULL) {
+                   entry_prev->next = ptr;
+                }
+                else {
+                   /* removing first entry - head of list should point to next entry */               
+                   *entry_in_table = ptr;
+                } 
+            }
+            else {
+              /* entry not expired - advance entry_prev to current entry*/
+              entry_prev = entry;
+	        }
+            entry = ptr;
+        }
+    }
+    if (table->count < (table->size/4)) {
+	/* hash table (the array size) too big for the amount of values it contains perform rehash */
+        sigar_cache_rehash(table);
+    }
+}
+
+   
+
+
 sigar_cache_entry_t *sigar_cache_find(sigar_cache_t *table,
                                       sigar_uint64_t key)
 {
     sigar_cache_entry_t *entry, **ptr;
+    sigar_perform_cleanup_if_necessary(table);
 
     for (ptr = SIGAR_CACHE_IX(table, key), entry = *ptr;
          entry;
          ptr = &entry->next, entry = *ptr)
     {
         if (entry->id == key) {
+            entry->last_access_time = sigar_time_now_millis();
             return entry;
         }
     }
@@ -123,17 +194,19 @@ sigar_cache_entry_t *sigar_cache_get(sigar_cache_t *table,
                                      sigar_uint64_t key)
 {
     sigar_cache_entry_t *entry, **ptr;
+    sigar_perform_cleanup_if_necessary(table);
 
     for (ptr = SIGAR_CACHE_IX(table, key), entry = *ptr;
          entry;
          ptr = &entry->next, entry = *ptr)
     {
         if (entry->id == key) {
+            entry->last_access_time = sigar_time_now_millis();
             return entry;
         }
     }
 
-    if (table->count++ > table->size) {
+    if (++table->count > table->size) {
         sigar_cache_rehash(table);
 
         for (ptr = SIGAR_CACHE_IX(table, key), entry = *ptr;
@@ -147,6 +220,7 @@ sigar_cache_entry_t *sigar_cache_get(sigar_cache_t *table,
     entry->id = key;
     entry->value = NULL;
     entry->next = NULL;
+    entry->last_access_time = sigar_time_now_millis();
 
     return entry;
 }
diff --git a/src/sigar_ptql.c b/src/sigar_ptql.c
index 34ac7279..9311923f 100644
--- a/src/sigar_ptql.c
+++ b/src/sigar_ptql.c
@@ -1325,6 +1325,14 @@ static ptql_lookup_t PTQL_Cpu[] = {
     { NULL }
 };
 
+static ptql_lookup_t PTQL_Disk_IO[] = {
+    { "BytesRead", PTQL_LOOKUP_ENTRY(proc_disk_io, bytes_read, UI64) },
+    { "BytesWritten",      PTQL_LOOKUP_ENTRY(proc_disk_io, bytes_written, UI64) },
+    { "BytesTotal",       PTQL_LOOKUP_ENTRY(proc_disk_io, bytes_total, UI64) },
+    { NULL }
+};
+
+
 static ptql_lookup_t PTQL_CredName[] = {
     { "User",  PTQL_LOOKUP_ENTRY(proc_cred_name, user, STR) },
     { "Group", PTQL_LOOKUP_ENTRY(proc_cred_name, group, STR) },
@@ -1411,6 +1419,7 @@ static ptql_entry_t ptql_map[] = {
     { "Port",     PTQL_Port },
     { "Pid",      PTQL_Pid },
     { "Service",  PTQL_Service },
+    { "Disk_IO",   PTQL_Disk_IO },
     { NULL }
 };