diff --git a/common/src/main/java/io/netty/util/concurrent/DefaultProgressivePromise.java b/common/src/main/java/io/netty/util/concurrent/DefaultProgressivePromise.java
index d3c32a5386..164fac5136 100644
--- a/common/src/main/java/io/netty/util/concurrent/DefaultProgressivePromise.java
+++ b/common/src/main/java/io/netty/util/concurrent/DefaultProgressivePromise.java
@@ -55,7 +55,12 @@ public class DefaultProgressivePromise<V> extends DefaultPromise<V> implements P
 
     @Override
     public boolean tryProgress(long progress, long total) {
-        if (progress < 0 || progress > total || isDone()) {
+        if (total < 0) {
+            total = -1;
+            if (progress < 0 || isDone()) {
+                return false;
+            }
+        } else if (progress < 0 || progress > total || isDone()) {
             return false;
         }
 
diff --git a/example/src/main/java/io/netty/example/http/file/HttpStaticFileServerHandler.java b/example/src/main/java/io/netty/example/http/file/HttpStaticFileServerHandler.java
index 9e85fa0f98..948cc45461 100644
--- a/example/src/main/java/io/netty/example/http/file/HttpStaticFileServerHandler.java
+++ b/example/src/main/java/io/netty/example/http/file/HttpStaticFileServerHandler.java
@@ -22,6 +22,7 @@ import io.netty.channel.ChannelFutureListener;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelProgressiveFuture;
 import io.netty.channel.ChannelProgressiveFutureListener;
+import io.netty.channel.DefaultFileRegion;
 import io.netty.channel.SimpleChannelInboundHandler;
 import io.netty.handler.codec.http.DefaultFullHttpResponse;
 import io.netty.handler.codec.http.DefaultHttpResponse;
@@ -106,6 +107,12 @@ public class HttpStaticFileServerHandler extends SimpleChannelInboundHandler<Ful
     public static final String HTTP_DATE_GMT_TIMEZONE = "GMT";
     public static final int HTTP_CACHE_SECONDS = 60;
 
+    private final boolean useSendFile;
+
+    public HttpStaticFileServerHandler(boolean useSendFile) {
+        this.useSendFile = useSendFile;
+    }
+
     @Override
     public void channelRead0(
             ChannelHandlerContext ctx, FullHttpRequest request) throws Exception {
@@ -181,11 +188,25 @@ public class HttpStaticFileServerHandler extends SimpleChannelInboundHandler<Ful
 
         // Write the initial line and the header.
         ctx.write(response);
+
         // Write the content.
-        ctx.write(new ChunkedFile(raf, 0, fileLength, 8192), ctx.newProgressivePromise()).addListener(new ChannelProgressiveFutureListener() {
+        ChannelFuture sendFileFuture;
+        if (useSendFile) {
+            sendFileFuture =
+                    ctx.write(new DefaultFileRegion(raf.getChannel(), 0, fileLength), ctx.newProgressivePromise());
+        } else {
+            sendFileFuture =
+                    ctx.write(new ChunkedFile(raf, 0, fileLength, 8192), ctx.newProgressivePromise());
+        }
+
+        sendFileFuture.addListener(new ChannelProgressiveFutureListener() {
             @Override
-            public void operationProgressed(ChannelProgressiveFuture future, long progress, long total) throws Exception {
-                System.err.println("Transfer progress: " + progress);
+            public void operationProgressed(ChannelProgressiveFuture future, long progress, long total) {
+                if (total < 0) { // total unknown
+                    System.err.println("Transfer progress: " + progress);
+                } else {
+                    System.err.println("Transfer progress: " + progress + " / " + total);
+                }
             }
 
             @Override
@@ -193,13 +214,14 @@ public class HttpStaticFileServerHandler extends SimpleChannelInboundHandler<Ful
                 System.err.println("Transfer complete.");
             }
         });
+
         // Write the end marker
-        ChannelFuture writeFuture = ctx.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT);
+        ChannelFuture lastContentFuture = ctx.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT);
 
         // Decide whether to close the connection or not.
         if (!isKeepAlive(request)) {
             // Close the connection when the whole content is written out.
-            writeFuture.addListener(ChannelFutureListener.CLOSE);
+            lastContentFuture.addListener(ChannelFutureListener.CLOSE);
         }
     }
 
diff --git a/example/src/main/java/io/netty/example/http/file/HttpStaticFileServerInitializer.java b/example/src/main/java/io/netty/example/http/file/HttpStaticFileServerInitializer.java
index 04af9ff0bc..5edb82af5d 100644
--- a/example/src/main/java/io/netty/example/http/file/HttpStaticFileServerInitializer.java
+++ b/example/src/main/java/io/netty/example/http/file/HttpStaticFileServerInitializer.java
@@ -39,6 +39,6 @@ public class HttpStaticFileServerInitializer extends ChannelInitializer<SocketCh
         pipeline.addLast("encoder", new HttpResponseEncoder());
         pipeline.addLast("chunkedWriter", new ChunkedWriteHandler());
 
-        pipeline.addLast("handler", new HttpStaticFileServerHandler());
+        pipeline.addLast("handler", new HttpStaticFileServerHandler(true)); // Specify false if SSL.
     }
 }
diff --git a/handler/src/main/java/io/netty/handler/stream/ChunkedWriteHandler.java b/handler/src/main/java/io/netty/handler/stream/ChunkedWriteHandler.java
index a6706cec4c..db9d62f179 100644
--- a/handler/src/main/java/io/netty/handler/stream/ChunkedWriteHandler.java
+++ b/handler/src/main/java/io/netty/handler/stream/ChunkedWriteHandler.java
@@ -296,11 +296,11 @@ public class ChunkedWriteHandler
                             if (!future.isSuccess()) {
                                 closeInput((ChunkedInput<?>) pendingMessage);
                                 currentWrite.fail(future.cause());
-                            } else if (isWritable()) {
-                                currentWrite.progress();
-                                resumeTransfer();
                             } else {
                                 currentWrite.progress();
+                                if (isWritable()) {
+                                    resumeTransfer();
+                                }
                             }
                         }
                     });
diff --git a/transport/src/main/java/io/netty/channel/AbstractChannel.java b/transport/src/main/java/io/netty/channel/AbstractChannel.java
index c51cd072b4..50e4c4b8f7 100644
--- a/transport/src/main/java/io/netty/channel/AbstractChannel.java
+++ b/transport/src/main/java/io/netty/channel/AbstractChannel.java
@@ -794,13 +794,16 @@ public abstract class AbstractChannel extends DefaultAttributeMap implements Cha
      * Calculate the number of bytes a message takes up in memory. Sub-classes may override this if they use different
      * messages then {@link ByteBuf} or {@link ByteBufHolder}. If the size can not be calculated 0 should be returned.
      */
-    protected int calculateMessageSize(Object message) {
+    protected long calculateMessageSize(Object message) {
         if (message instanceof ByteBuf) {
             return ((ByteBuf) message).readableBytes();
         }
         if (message instanceof ByteBufHolder) {
             return ((ByteBufHolder) message).content().readableBytes();
         }
+        if (message instanceof FileRegion) {
+            return ((FileRegion) message).count();
+        }
         return 0;
     }
 
diff --git a/transport/src/main/java/io/netty/channel/ChannelOutboundBuffer.java b/transport/src/main/java/io/netty/channel/ChannelOutboundBuffer.java
index 5d444b465b..2d9fc73323 100644
--- a/transport/src/main/java/io/netty/channel/ChannelOutboundBuffer.java
+++ b/transport/src/main/java/io/netty/channel/ChannelOutboundBuffer.java
@@ -145,7 +145,7 @@ public final class ChannelOutboundBuffer {
             unflushed = this.unflushed;
         }
 
-        final int size = channel.calculateMessageSize(msg);
+        final long size = channel.calculateMessageSize(msg);
         incrementPendingOutboundBytes(size);
 
         unflushed[unflushedCount] = msg;
@@ -249,7 +249,7 @@ public final class ChannelOutboundBuffer {
         tail = n;
     }
 
-    private void incrementPendingOutboundBytes(int size) {
+    private void incrementPendingOutboundBytes(long size) {
         if (size == 0) {
             return;
         }