diff --git a/klippy/reactor.py b/klippy/reactor.py
index 69eedcbd..5b1ec569 100644
--- a/klippy/reactor.py
+++ b/klippy/reactor.py
@@ -50,9 +50,10 @@ class ReactorCallback:
         return self.reactor.NEVER
 
 class ReactorFileHandler:
-    def __init__(self, fd, callback):
+    def __init__(self, fd, read_callback, write_callback):
         self.fd = fd
-        self.callback = callback
+        self.read_callback = read_callback
+        self.write_callback = write_callback
     def fileno(self):
         return self.fd
 
@@ -107,7 +108,8 @@ class SelectReactor:
         self._pipe_fds = None
         self._async_queue = queue.Queue()
         # File descriptors
-        self._fds = []
+        self._read_fds = []
+        self._write_fds = []
         # Greenlets
         self._g_dispatch = None
         self._greenlets = []
@@ -236,12 +238,26 @@ class SelectReactor:
     def mutex(self, is_locked=False):
         return ReactorMutex(self, is_locked)
     # File descriptors
-    def register_fd(self, fd, callback):
-        file_handler = ReactorFileHandler(fd, callback)
-        self._fds.append(file_handler)
+    def register_fd(self, fd, read_callback, write_callback=None):
+        file_handler = ReactorFileHandler(fd, read_callback, write_callback)
+        self.set_fd_wake(file_handle, True, False)
         return file_handler
     def unregister_fd(self, file_handler):
-        self._fds.pop(self._fds.index(file_handler))
+        if file_handler in self._read_fds:
+            self._read_fds.pop(self._read_fds.index(file_handler))
+        if file_handler in self._write_fds:
+            self._write_fds.pop(self._write_fds.index(file_handler))
+    def set_fd_wake(self, file_handler, is_readable=True, is_writeable=False):
+        if file_hander in self._read_fds:
+            if not is_readable:
+                self._read_fds.pop(self._read_fds.index(file_handler))
+        elif is_readable:
+            self._read_fds.append(file_handler)
+        if file_hander in self._write_fds:
+            if not is_writeable:
+                self._write_fds.pop(self._write_fds.index(file_handler))
+        elif is_writeable:
+            self._write_fds.append(file_handler)
     # Main loop
     def _dispatch_loop(self):
         self._g_dispatch = g_dispatch = greenlet.getcurrent()
@@ -250,11 +266,18 @@ class SelectReactor:
         while self._process:
             timeout = self._check_timers(eventtime, busy)
             busy = False
-            res = select.select(self._fds, [], [], timeout)
+            res = select.select(self._read_fds, self.write_fds, [], timeout)
             eventtime = self.monotonic()
             for fd in res[0]:
                 busy = True
-                fd.callback(eventtime)
+                fd.read_callback(eventtime)
+                if g_dispatch is not self._g_dispatch:
+                    self._end_greenlet(g_dispatch)
+                    eventtime = self.monotonic()
+                    break
+            for fd in res[1]:
+                busy = True
+                fd.write_callback(eventtime)
                 if g_dispatch is not self._g_dispatch:
                     self._end_greenlet(g_dispatch)
                     eventtime = self.monotonic()
@@ -289,10 +312,10 @@ class PollReactor(SelectReactor):
         self._poll = select.poll()
         self._fds = {}
     # File descriptors
-    def register_fd(self, fd, callback):
-        file_handler = ReactorFileHandler(fd, callback)
+    def register_fd(self, fd, read_callback, write_callback=None):
+        file_handler = ReactorFileHandler(fd, read_callback, write_callback)
         fds = self._fds.copy()
-        fds[fd] = callback
+        fds[fd] = file_handler
         self._fds = fds
         self._poll.register(file_handler, select.POLLIN | select.POLLHUP)
         return file_handler
@@ -301,6 +324,13 @@ class PollReactor(SelectReactor):
         fds = self._fds.copy()
         del fds[file_handler.fd]
         self._fds = fds
+    def set_fd_wake(self, file_handler, is_readable=True, is_writeable=False):
+        flags = select.POLLHUP
+        if is_readable:
+            flags |= select.POLLIN
+        if is_writeable:
+            flags |= select.POLLOUT
+        self._poll.modify(file_handler, flags)
     # Main loop
     def _dispatch_loop(self):
         self._g_dispatch = g_dispatch = greenlet.getcurrent()
@@ -313,11 +343,18 @@ class PollReactor(SelectReactor):
             eventtime = self.monotonic()
             for fd, event in res:
                 busy = True
-                self._fds[fd](eventtime)
-                if g_dispatch is not self._g_dispatch:
-                    self._end_greenlet(g_dispatch)
-                    eventtime = self.monotonic()
-                    break
+                if event & (select.POLLIN | select.POLLHUP):
+                    self._fds[fd].read_callback(eventtime)
+                    if g_dispatch is not self._g_dispatch:
+                        self._end_greenlet(g_dispatch)
+                        eventtime = self.monotonic()
+                        break
+                if event & select.POLLOUT:
+                    self._fds[fd].write_callback(eventtime)
+                    if g_dispatch is not self._g_dispatch:
+                        self._end_greenlet(g_dispatch)
+                        eventtime = self.monotonic()
+                        break
         self._g_dispatch = None
 
 class EPollReactor(SelectReactor):
@@ -326,8 +363,8 @@ class EPollReactor(SelectReactor):
         self._epoll = select.epoll()
         self._fds = {}
     # File descriptors
-    def register_fd(self, fd, callback):
-        file_handler = ReactorFileHandler(fd, callback)
+    def register_fd(self, fd, read_callback, write_callback=None):
+        file_handler = ReactorFileHandler(fd, read_callback, write_callback)
         fds = self._fds.copy()
         fds[fd] = callback
         self._fds = fds
@@ -338,6 +375,13 @@ class EPollReactor(SelectReactor):
         fds = self._fds.copy()
         del fds[file_handler.fd]
         self._fds = fds
+    def set_fd_wake(self, file_handler, is_readable=True, is_writeable=False):
+        flags = select.POLLHUP
+        if is_readable:
+            flags |= select.EPOLLIN
+        if is_writeable:
+            flags |= select.EPOLLOUT
+        self._epoll.modify(file_handler, flags)
     # Main loop
     def _dispatch_loop(self):
         self._g_dispatch = g_dispatch = greenlet.getcurrent()
@@ -350,11 +394,18 @@ class EPollReactor(SelectReactor):
             eventtime = self.monotonic()
             for fd, event in res:
                 busy = True
-                self._fds[fd](eventtime)
-                if g_dispatch is not self._g_dispatch:
-                    self._end_greenlet(g_dispatch)
-                    eventtime = self.monotonic()
-                    break
+                if event & (select.EPOLLIN | select.EPOLLHUP):
+                    self._fds[fd].read_callback(eventtime)
+                    if g_dispatch is not self._g_dispatch:
+                        self._end_greenlet(g_dispatch)
+                        eventtime = self.monotonic()
+                        break
+                if event & select.EPOLLOUT:
+                    self._fds[fd].write_callback(eventtime)
+                    if g_dispatch is not self._g_dispatch:
+                        self._end_greenlet(g_dispatch)
+                        eventtime = self.monotonic()
+                        break
         self._g_dispatch = None
 
 # Use the poll based reactor if it is available