--- synapse/app/_base.py.orig	2017-10-02 12:52:03 UTC
+++ synapse/app/_base.py
@@ -15,7 +15,6 @@
 import gc
 import logging
 
-import affinity
 from daemonize import Daemonize
 from synapse.util import PreserveLoggingContext
 from synapse.util.rlimit import change_resource_limit
@@ -41,8 +40,7 @@ def start_worker_reactor(appname, config
         config.gc_thresholds,
         config.worker_pid_file,
         config.worker_daemonize,
-        config.worker_cpu_affinity,
-        logger,
+        logger
     )
 
 
@@ -52,7 +50,6 @@ def start_reactor(
         gc_thresholds,
         pid_file,
         daemonize,
-        cpu_affinity,
         logger,
 ):
     """ Run the reactor in the main process
@@ -66,7 +63,6 @@ def start_reactor(
         gc_thresholds:
         pid_file (str): name of pid file to write to if daemonize is True
         daemonize (bool): true to run the reactor in a background process
-        cpu_affinity (int|None): cpu affinity mask
         logger (logging.Logger): logger instance to pass to Daemonize
     """
 
@@ -77,9 +73,6 @@ def start_reactor(
         # between the sentinel and `run` logcontexts.
         with PreserveLoggingContext():
             logger.info("Running")
-            if cpu_affinity is not None:
-                logger.info("Setting CPU affinity to %s" % cpu_affinity)
-                affinity.set_process_affinity_mask(0, cpu_affinity)
             change_resource_limit(soft_file_limit)
             if gc_thresholds:
                 gc.set_threshold(*gc_thresholds)
--- synapse/app/homeserver.py.orig	2017-10-02 12:52:03 UTC
+++ synapse/app/homeserver.py
@@ -442,7 +442,6 @@ def run(hs):
         hs.config.gc_thresholds,
         hs.config.pid_file,
         hs.config.daemonize,
-        hs.config.cpu_affinity,
         logger,
     )
 
--- synapse/config/server.py.orig	2017-10-02 12:52:03 UTC
+++ synapse/config/server.py
@@ -30,7 +30,6 @@ class ServerConfig(Config):
         self.user_agent_suffix = config.get("user_agent_suffix")
         self.use_frozen_dicts = config.get("use_frozen_dicts", False)
         self.public_baseurl = config.get("public_baseurl")
-        self.cpu_affinity = config.get("cpu_affinity")
 
         # Whether to send federation traffic out in this process. This only
         # applies to some federation traffic, and so shouldn't be used to
@@ -155,27 +154,6 @@ class ServerConfig(Config):
         # When running as a daemon, the file to store the pid in
         pid_file: %(pid_file)s
 
-        # CPU affinity mask. Setting this restricts the CPUs on which the
-        # process will be scheduled. It is represented as a bitmask, with the
-        # lowest order bit corresponding to the first logical CPU and the
-        # highest order bit corresponding to the last logical CPU. Not all CPUs
-        # may exist on a given system but a mask may specify more CPUs than are
-        # present.
-        #
-        # For example:
-        #    0x00000001  is processor #0,
-        #    0x00000003  is processors #0 and #1,
-        #    0xFFFFFFFF  is all processors (#0 through #31).
-        #
-        # Pinning a Python process to a single CPU is desirable, because Python
-        # is inherently single-threaded due to the GIL, and can suffer a
-        # 30-40%% slowdown due to cache blow-out and thread context switching
-        # if the scheduler happens to schedule the underlying threads across
-        # different cores. See
-        # https://www.mirantis.com/blog/improve-performance-python-programs-restricting-single-cpu/.
-        #
-        # cpu_affinity: 0xFFFFFFFF
-
         # Whether to serve a web client from the HTTP/HTTPS root resource.
         web_client: True
 
--- synapse/config/workers.py.orig	2017-10-02 12:52:03 UTC
+++ synapse/config/workers.py
@@ -33,7 +33,6 @@ class WorkerConfig(Config):
         self.worker_name = config.get("worker_name", self.worker_app)
 
         self.worker_main_http_uri = config.get("worker_main_http_uri", None)
-        self.worker_cpu_affinity = config.get("worker_cpu_affinity")
 
         if self.worker_listeners:
             for listener in self.worker_listeners:
--- synapse/python_dependencies.py.orig	2017-10-02 12:52:03 UTC
+++ synapse/python_dependencies.py
@@ -40,7 +40,6 @@ REQUIREMENTS = {
     "pymacaroons-pynacl": ["pymacaroons"],
     "msgpack-python>=0.3.0": ["msgpack"],
     "phonenumbers>=8.2.0": ["phonenumbers"],
-    "affinity": ["affinity"],
 }
 CONDITIONAL_REQUIREMENTS = {
     "web_client": {