diff --git a/include/libtorrent/Makefile.am b/include/libtorrent/Makefile.am
index 433b9ef3c..24e2377c7 100644
--- a/include/libtorrent/Makefile.am
+++ b/include/libtorrent/Makefile.am
@@ -142,7 +142,6 @@ nobase_include_HEADERS = \
   torrent_status.hpp           \
   udp_socket.hpp               \
   udp_tracker_connection.hpp   \
-  uncork_interface.hpp         \
   union_endpoint.hpp           \
   upnp.hpp                     \
   utp_socket_manager.hpp       \
diff --git a/include/libtorrent/aux_/session_impl.hpp b/include/libtorrent/aux_/session_impl.hpp
index e3b6bc004..d52aaf529 100644
--- a/include/libtorrent/aux_/session_impl.hpp
+++ b/include/libtorrent/aux_/session_impl.hpp
@@ -36,7 +36,6 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/config.hpp"
 #include "libtorrent/aux_/session_settings.hpp"
 #include "libtorrent/aux_/session_interface.hpp"
-#include "libtorrent/uncork_interface.hpp"
 #include "libtorrent/linked_list.hpp"
 #include "libtorrent/torrent_peer.hpp"
 #include "libtorrent/torrent_peer_allocator.hpp"
@@ -192,7 +191,6 @@ namespace libtorrent
 			, aux::portmap_callback
 			, aux::lsd_callback
 			, boost::noncopyable
-			, uncork_interface
 			, single_threaded
 			, aux::error_handler_interface
 		{
@@ -638,14 +636,6 @@ namespace libtorrent
 			mutable std::mutex mut;
 			mutable std::condition_variable cond;
 
-			// cork a peer and schedule a delayed uncork
-			// does nothing if the peer is already corked
-			void cork_burst(peer_connection* p) override;
-
-			// uncork all peers added to the delayed uncork queue
-			// implements uncork_interface
-			virtual void do_delayed_uncork() override;
-
 			// implements session_interface
 			virtual tcp::endpoint bind_outgoing_socket(socket_type& s, address
 				const& remote_address, error_code& ec) const override;
@@ -1210,14 +1200,6 @@ namespace libtorrent
 
 			// is true if the session is paused
 			bool m_paused = false;
-
-			// this is a list of peer connections who have been
-			// corked (i.e. their network socket) and needs to be
-			// uncorked at the end of the burst of events. This is
-			// here to coalesce the effects of bursts of events
-			// into fewer network writes, saving CPU and possibly
-			// ending up sending larger network packets
-			std::vector<peer_connection*> m_delayed_uncorks;
 		};
 
 #ifndef TORRENT_DISABLE_LOGGING
diff --git a/include/libtorrent/aux_/session_interface.hpp b/include/libtorrent/aux_/session_interface.hpp
index 241b169e9..752132b1d 100644
--- a/include/libtorrent/aux_/session_interface.hpp
+++ b/include/libtorrent/aux_/session_interface.hpp
@@ -191,10 +191,6 @@ namespace libtorrent { namespace aux
 
 		virtual peer_id const& get_peer_id() const = 0;
 
-		// cork a peer and schedule a delayed uncork
-		// does nothing if the peer is already corked
-		virtual void cork_burst(peer_connection* p) = 0;
-
 		virtual void close_connection(peer_connection* p, error_code const& ec) = 0;
 		virtual int num_connections() const = 0;
 
diff --git a/include/libtorrent/disk_io_thread.hpp b/include/libtorrent/disk_io_thread.hpp
index a1c76fbb2..1e83518ed 100644
--- a/include/libtorrent/disk_io_thread.hpp
+++ b/include/libtorrent/disk_io_thread.hpp
@@ -279,7 +279,6 @@ namespace libtorrent
 	{
 		disk_io_thread(io_service& ios
 			, counters& cnt
-			, void* userdata
 			, int block_size = 16 * 1024);
 		~disk_io_thread();
 
@@ -419,7 +418,7 @@ namespace libtorrent
 		int do_tick(disk_io_job* j, jobqueue_t& completed_jobs);
 		int do_resolve_links(disk_io_job* j, jobqueue_t& completed_jobs);
 
-		void call_job_handlers(void* userdata);
+		void call_job_handlers();
 
 	private:
 
diff --git a/include/libtorrent/peer_connection.hpp b/include/libtorrent/peer_connection.hpp
index 0e3976584..a34dff3b4 100644
--- a/include/libtorrent/peer_connection.hpp
+++ b/include/libtorrent/peer_connection.hpp
@@ -63,6 +63,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/debug.hpp"
 #include "libtorrent/span.hpp"
 #include "libtorrent/piece_block.hpp"
+#include "libtorrent/peer_info.hpp"
 
 #include <ctime>
 #include <algorithm>
@@ -76,7 +77,6 @@ POSSIBILITY OF SUCH DAMAGE.
 namespace libtorrent
 {
 	class torrent;
-	struct peer_info;
 	struct disk_io_job;
 	struct disk_interface;
 	struct torrent_peer;
@@ -166,7 +166,6 @@ namespace libtorrent
 			, m_snubbed(false)
 			, m_interesting(false)
 			, m_choked(true)
-			, m_corked(false)
 			, m_ignore_stats(false)
 		{}
 
@@ -230,13 +229,6 @@ namespace libtorrent
 		// we have choked the upload to the peer
 		bool m_choked:1;
 
-		// when this is set, the peer_connection socket is
-		// corked, similar to the linux TCP feature TCP_CORK.
-		// we won't send anything to the actual socket, just
-		// buffer messages up in the application layer send
-		// buffer, and send it once we're uncorked.
-		bool m_corked:1;
-
 		// when this is set, the transfer stats for this connection
 		// is not included in the torrent or session stats
 		bool m_ignore_stats:1;
@@ -263,6 +255,7 @@ namespace libtorrent
 	{
 	friend class invariant_access;
 	friend class torrent;
+	friend struct cork;
 	public:
 
 		void on_exception(std::exception const& e) override;
@@ -635,10 +628,6 @@ namespace libtorrent
 		void send_buffer(char const* begin, int size, int flags = 0);
 		void setup_send();
 
-		void cork_socket() { TORRENT_ASSERT(!m_corked); m_corked = true; }
-		bool is_corked() const { return m_corked; }
-		void uncork_socket();
-
 		void append_send_buffer(char* buffer, int size
 			, chained_buffer::free_buffer_fun destructor = &nop
 			, void* userdata = nullptr, block_cache_reference ref
@@ -1218,16 +1207,27 @@ namespace libtorrent
 	{
 		explicit cork(peer_connection& p): m_pc(p)
 		{
-			if (m_pc.is_corked()) return;
-			m_pc.cork_socket();
+			if (m_pc.m_channel_state[peer_connection::upload_channel] & peer_info::bw_network)
+				return;
+
+			// pretend that there's an outstanding send operation already, to
+			// prevent future calls to setup_send() from actually causing an
+			// asyc_send() to be issued.
+			m_pc.m_channel_state[peer_connection::upload_channel] |= peer_info::bw_network;
 			m_need_uncork = true;
 		}
-		~cork() { if (m_need_uncork) m_pc.uncork_socket(); }
+		cork(cork const&) = delete;
+		cork& operator=(cork const&) = delete;
+
+		~cork()
+		{
+			if (!m_need_uncork) return;
+			m_pc.m_channel_state[peer_connection::upload_channel] &= ~peer_info::bw_network;
+			m_pc.setup_send();
+		}
 	private:
 		peer_connection& m_pc;
 		bool m_need_uncork = false;
-
-		cork& operator=(cork const&);
 	};
 
 }
diff --git a/include/libtorrent/uncork_interface.hpp b/include/libtorrent/uncork_interface.hpp
deleted file mode 100644
index 4ab5dd569..000000000
--- a/include/libtorrent/uncork_interface.hpp
+++ /dev/null
@@ -1,58 +0,0 @@
-/*
-
-Copyright (c) 2012-2016, Arvid Norberg
-All rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions
-are met:
-
-    * Redistributions of source code must retain the above copyright
-      notice, this list of conditions and the following disclaimer.
-    * Redistributions in binary form must reproduce the above copyright
-      notice, this list of conditions and the following disclaimer in
-      the documentation and/or other materials provided with the distribution.
-    * Neither the name of the author nor the names of its
-      contributors may be used to endorse or promote products derived
-      from this software without specific prior written permission.
-
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
-AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
-IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
-ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
-LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
-CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
-SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
-INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
-CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
-ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
-POSSIBILITY OF SUCH DAMAGE.
-
-*/
-
-#ifndef TORRENT_UNCORK_INTERFACE_HPP
-#define TORRENT_UNCORK_INTERFACE_HPP
-
-#include "libtorrent/export.hpp"
-
-namespace libtorrent
-{
-	// the uncork interface is used by the disk_io_thread
-	// to indicate that it has called all the disk job handlers
-	// in the current batch. The intention is for the peer
-	// connections to be able to not issue any sends on their
-	// sockets until they have received all the disk jobs
-	// that are ready first. This makes the networking more
-	// efficient since it can send larger buffers down to the
-	// kernel per system call.
-	// uncorking refers to releasing the "cork" in the peers
-	// preventing them to issue sends
-	struct TORRENT_EXTRA_EXPORT uncork_interface
-	{
-		virtual void do_delayed_uncork() = 0;
-	protected:
-		~uncork_interface() {}
-	};
-}
-
-#endif
diff --git a/src/create_torrent.cpp b/src/create_torrent.cpp
index 0e306bd47..0018f0ae5 100644
--- a/src/create_torrent.cpp
+++ b/src/create_torrent.cpp
@@ -265,7 +265,7 @@ namespace libtorrent
 		// dummy torrent object pointer
 		std::shared_ptr<char> dummy;
 		counters cnt;
-		disk_io_thread disk_thread(ios, cnt, nullptr);
+		disk_io_thread disk_thread(ios, cnt);
 		disk_thread.set_num_threads(1);
 
 		storage_params params;
diff --git a/src/disk_io_thread.cpp b/src/disk_io_thread.cpp
index df17300b0..50f796f7f 100644
--- a/src/disk_io_thread.cpp
+++ b/src/disk_io_thread.cpp
@@ -46,7 +46,6 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/disk_buffer_pool.hpp"
 #include "libtorrent/disk_io_job.hpp"
 #include "libtorrent/alert_types.hpp"
-#include "libtorrent/uncork_interface.hpp"
 #include "libtorrent/performance_counters.hpp"
 #include "libtorrent/alert_manager.hpp"
 #include "libtorrent/debug.hpp"
@@ -179,13 +178,11 @@ namespace libtorrent
 
 	disk_io_thread::disk_io_thread(io_service& ios
 		, counters& cnt
-		, void* userdata
 		, int const block_size)
 		: m_generic_io_jobs(*this, generic_thread)
 		, m_generic_threads(m_generic_io_jobs, ios)
 		, m_hash_io_jobs(*this, hasher_thread)
 		, m_hash_threads(m_hash_io_jobs, ios)
-		, m_userdata(userdata)
 		, m_last_file_check(clock_type::now())
 		, m_disk_cache(block_size, ios, std::bind(&disk_io_thread::trigger_cache_trim, this))
 		, m_stats_counters(cnt)
@@ -3518,16 +3515,13 @@ namespace libtorrent
 			// we take this lock just to make the logging prettier (non-interleaved)
 			DLOG("posting job handlers (%d)\n", m_completed_jobs.size());
 
-			m_ios.post(std::bind(&disk_io_thread::call_job_handlers, this, m_userdata));
+			m_ios.post(std::bind(&disk_io_thread::call_job_handlers, this));
 			m_job_completions_in_flight = true;
 		}
 	}
 
 	// This is run in the network thread
-	// TODO: 2 it would be nice to get rid of m_userdata and just have a function
-	// object to pass all the job completions to. It could in turn be responsible
-	// for posting them to the correct io_service
-	void disk_io_thread::call_job_handlers(void* userdata)
+	void disk_io_thread::call_job_handlers()
 	{
 		std::unique_lock<std::mutex> l(m_completed_jobs_mutex);
 
@@ -3539,7 +3533,6 @@ namespace libtorrent
 		disk_io_job* j = m_completed_jobs.get_all();
 		l.unlock();
 
-		uncork_interface* uncork = static_cast<uncork_interface*>(userdata);
 		std::array<disk_io_job*, 64> to_delete;
 		int cnt = 0;
 
@@ -3564,10 +3557,6 @@ namespace libtorrent
 		}
 
 		if (cnt > 0) free_jobs(to_delete.data(), cnt);
-
-		// uncork all peers who received a disk event. This is
-		// to coalesce all the socket writes caused by the events.
-		if (uncork) uncork->do_delayed_uncork();
 	}
 
 #if TORRENT_USE_INVARIANT_CHECKS
diff --git a/src/peer_connection.cpp b/src/peer_connection.cpp
index 4e485e822..f26381ea1 100644
--- a/src/peer_connection.cpp
+++ b/src/peer_connection.cpp
@@ -2986,10 +2986,6 @@ namespace libtorrent
 			m_channel_state[download_channel] &= ~peer_info::bw_disk;
 		}
 
-		// flush send buffer at the end of
-		// this burst of disk events
-//		m_ses.cork_burst(this);
-
 		INVARIANT_CHECK;
 
 		if (!t)
@@ -5258,10 +5254,6 @@ namespace libtorrent
 
 		if (m_disconnecting) return;
 
-		// flush send buffer at the end of
-		// this burst of disk events
-//		m_ses.cork_burst(this);
-
 		if (!t)
 		{
 			disconnect(j->error.ec, op_file_read);
@@ -5423,14 +5415,6 @@ namespace libtorrent
 		return ret;
 	}
 
-	void peer_connection::uncork_socket()
-	{
-		TORRENT_ASSERT(is_single_thread());
-		if (!m_corked) return;
-		m_corked = false;
-		setup_send();
-	}
-
 	void peer_connection::setup_send()
 	{
 		TORRENT_ASSERT(is_single_thread());
@@ -5439,7 +5423,16 @@ namespace libtorrent
 		// we may want to request more quota at this point
 		request_bandwidth(upload_channel);
 
-		if (m_channel_state[upload_channel] & peer_info::bw_network) return;
+		// if we already have an outstanding send operation, don't issue another
+		// one, instead accrue more send buffer to coalesce for the next write
+		if (m_channel_state[upload_channel] & peer_info::bw_network)
+		{
+#ifndef TORRENT_DISABLE_LOGGING
+			peer_log(peer_log_alert::outgoing, "CORKED_WRITE", "bytes: %d"
+				, int(m_send_buffer.size()));
+#endif
+			return;
+		}
 
 		if (m_send_barrier == 0)
 		{
@@ -5470,7 +5463,6 @@ namespace libtorrent
 		}
 
 		int const quota_left = m_quota[upload_channel];
-
 		if (m_send_buffer.empty()
 			&& m_reading_bytes > 0
 			&& quota_left > 0)
@@ -5542,24 +5534,13 @@ namespace libtorrent
 			return;
 		}
 
-		// send the actual buffer
-		int amount_to_send = m_send_buffer.size();
-		if (amount_to_send > quota_left)
-			amount_to_send = quota_left;
-		if (amount_to_send > m_send_barrier)
-			amount_to_send = m_send_barrier;
+		int const amount_to_send = std::min({
+			int(m_send_buffer.size())
+			, quota_left
+			, m_send_barrier});
 
 		TORRENT_ASSERT(amount_to_send > 0);
 
-		if (m_corked)
-		{
-#ifndef TORRENT_DISABLE_LOGGING
-			peer_log(peer_log_alert::outgoing, "CORKED_WRITE", "bytes: %d"
-				, amount_to_send);
-#endif
-			return;
-		}
-
 		TORRENT_ASSERT((m_channel_state[upload_channel] & peer_info::bw_network) == 0);
 #ifndef TORRENT_DISABLE_LOGGING
 		peer_log(peer_log_alert::outgoing, "ASYNC_WRITE", "bytes: %d", amount_to_send);
@@ -5816,11 +5797,11 @@ namespace libtorrent
 		// to keep the object alive through the exit check
 		std::shared_ptr<peer_connection> me(self());
 
+		TORRENT_ASSERT(bytes_transferred > 0);
+
 		// flush the send buffer at the end of this function
 		cork _c(*this);
 
-		TORRENT_ASSERT(bytes_transferred > 0);
-
 		// if we received exactly as many bytes as we provided a receive buffer
 		// for. There most likely are more bytes to read, and we should grow our
 		// receive buffer.
@@ -6230,8 +6211,8 @@ namespace libtorrent
 		m_last_sent = now;
 
 #if TORRENT_USE_ASSERTS
-		std::int64_t cur_payload_ul = m_statistics.last_payload_uploaded();
-		std::int64_t cur_protocol_ul = m_statistics.last_protocol_uploaded();
+		std::int64_t const cur_payload_ul = m_statistics.last_payload_uploaded();
+		std::int64_t const cur_protocol_ul = m_statistics.last_protocol_uploaded();
 #endif
 		on_sent(error, bytes_transferred);
 #if TORRENT_USE_ASSERTS
diff --git a/src/session_impl.cpp b/src/session_impl.cpp
index 1eda77224..3e9ba01d2 100644
--- a/src/session_impl.cpp
+++ b/src/session_impl.cpp
@@ -398,8 +398,7 @@ namespace aux {
 		, m_ssl_ctx(m_io_service, boost::asio::ssl::context::sslv23)
 #endif
 		, m_alerts(m_settings.get_int(settings_pack::alert_queue_size), alert::all_categories)
-		, m_disk_thread(m_io_service, m_stats_counters
-			, static_cast<uncork_interface*>(this))
+		, m_disk_thread(m_io_service, m_stats_counters)
 		, m_download_rate(peer_connection::download_channel)
 		, m_upload_rate(peer_connection::upload_channel)
 		, m_tracker_manager(
@@ -4141,23 +4140,6 @@ namespace aux {
 		}
 	}
 
-	void session_impl::cork_burst(peer_connection* p)
-	{
-		TORRENT_ASSERT(is_single_thread());
-		if (p->is_corked()) return;
-		p->cork_socket();
-		m_delayed_uncorks.push_back(p);
-	}
-
-	void session_impl::do_delayed_uncork()
-	{
-		m_stats_counters.inc_stats_counter(counters::on_disk_counter);
-		TORRENT_ASSERT(is_single_thread());
-		for (peer_connection* p : m_delayed_uncorks)
-			p->uncork_socket();
-		m_delayed_uncorks.clear();
-	}
-
 	std::shared_ptr<torrent> session_impl::delay_load_torrent(sha1_hash const& info_hash
 		, peer_connection* pc)
 	{
diff --git a/test/test_storage.cpp b/test/test_storage.cpp
index 970dc78d4..2f5448417 100644
--- a/test/test_storage.cpp
+++ b/test/test_storage.cpp
@@ -450,7 +450,7 @@ void test_check_files(std::string const& test_path
 	file_pool fp;
 	boost::asio::io_service ios;
 	counters cnt;
-	disk_io_thread io(ios, cnt, nullptr);
+	disk_io_thread io(ios, cnt);
 	io.set_num_threads(1);
 	disk_buffer_pool dp(16 * 1024, ios, std::bind(&nop));
 	storage_params p;