StdNetBind probes for UDP GSO and GRO support at runtime. UDP GSO is
dependent on checksum offload support on the egress netdev. UDP GSO
will be disabled in the event sendmmsg() returns EIO, which is a strong
signal that the egress netdev does not support checksum offload.
The iperf3 results below demonstrate the effect of this commit between
two Linux computers with i5-12400 CPUs. There is roughly ~13us of round
trip latency between them.
The first result is from commit 052af4a without UDP GSO or GRO.
Starting Test: protocol: TCP, 1 streams, 131072 byte blocks
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-10.00 sec 9.85 GBytes 8.46 Gbits/sec 1139 3.01 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
Test Complete. Summary Results:
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 9.85 GBytes 8.46 Gbits/sec 1139 sender
[ 5] 0.00-10.04 sec 9.85 GBytes 8.42 Gbits/sec receiver
The second result is with UDP GSO and GRO.
Starting Test: protocol: TCP, 1 streams, 131072 byte blocks
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-10.00 sec 12.3 GBytes 10.6 Gbits/sec 232 3.15 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
Test Complete. Summary Results:
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 12.3 GBytes 10.6 Gbits/sec 232 sender
[ 5] 0.00-10.04 sec 12.3 GBytes 10.6 Gbits/sec receiver
Reviewed-by: Adrian Dewhurst <[email protected]>
Signed-off-by: Jordan Whited <[email protected]>
Signed-off-by: Jason A. Donenfeld <[email protected]>
tcpGRO() was using an incorrect IPv4 more fragments bit mask.
tcpPacketsCanCoalesce() was not distinguishing tcp6 from tcp4, and TTL
values were not compared. TTL values should be equal at the IP layer,
otherwise the packets should not coalesce. This tracks with the kernel.
Reviewed-by: Denton Gentry <[email protected]>
Signed-off-by: Jordan Whited <[email protected]>
Signed-off-by: Jason A. Donenfeld <[email protected]>
IP options were not being compared prior to coalescing. They are not
commonly used. Disqualification due to nonzero options is in line with
the kernel.
Reviewed-by: Denton Gentry <[email protected]>
Signed-off-by: Jordan Whited <[email protected]>
Signed-off-by: Jason A. Donenfeld <[email protected]>
In 9e2f386 ("conn, device, tun: implement vectorized I/O on Linux"), the
Linux-specific Bind implementation was collapsed into StdNetBind. This
introduced a race on StdNetEndpoint from getSrcFromControl() and
setSrcControl().
Remove the sync.Pool involved in the race, and simplify StdNetBind's
receive path to allocate StdNetEndpoint on the heap instead, with the
intent for it to be cleaned up by the GC, later. This essentially
reverts ef5c587 ("conn: remove the final alloc per packet receive"),
adding back that allocation, unfortunately.
This does slightly increase resident memory usage in higher throughput
scenarios. StdNetBind is the only Bind implementation that was using
this Endpoint recycling technique prior to this commit.
This is considered a stop-gap solution, and there are plans to replace
the allocation with a better mechanism.
Reported-by: lsc <[email protected]>
Link: https://lore.kernel.org/wireguard/[email protected]/
Fixes: 9e2f386 ("conn, device, tun: implement vectorized I/O on Linux")
Cc: Josh Bleecher Snyder <[email protected]>
Reviewed-by: James Tucker <[email protected]>
Signed-off-by: Jordan Whited <[email protected]>
Signed-off-by: Jason A. Donenfeld <[email protected]>
We only expect a single control message in the normal case, but this
would loop infinitely if there were more.
Reviewed-by: Adrian Dewhurst <[email protected]>
Signed-off-by: Jordan Whited <[email protected]>
Signed-off-by: Jason A. Donenfeld <[email protected]>
This commit updates StdNetBind.BatchSize() to return 1 instead of
IdealBatchSize for non-Linux platforms. Non-Linux platforms do not
yet benefit from values > 1, which only serves to increase memory
consumption.
Reviewed-by: James Tucker <[email protected]>
Signed-off-by: Jordan Whited <[email protected]>
Signed-off-by: Jason A. Donenfeld <[email protected]>
Enable TCP SACK for the gVisor Stack used in tun/netstack. This can
improve throughput by an order of magnitude in the presence of packet
loss.
Reviewed-by: James Tucker <[email protected]>
Signed-off-by: Jordan Whited <[email protected]>
Signed-off-by: Jason A. Donenfeld <[email protected]>
This commit re-slices received control messages in StdNetBind to the
value the OS reports on a successful read. Previously, the len of this
slice would always be srcControlSize, which could result in control
message values leaking through a sync.Pool round trip. This is
unlikely with the IP_PKTINFO socket option set successfully, but
should be guarded against.
Reviewed-by: James Tucker <[email protected]>
Signed-off-by: Jordan Whited <[email protected]>
Signed-off-by: Jason A. Donenfeld <[email protected]>
If RIO is unavailable, NewWinRingBind() falls back to StdNetBind.
StdNetBind uses x/net/ipv{4,6}.PacketConn for sending and receiving
datagrams, specifically via the {Read,Write}Batch methods.
These methods are unimplemented on Windows and will return runtime
errors as a result. Additionally, only Linux benefits from these
x/net types for reading and writing, so we update StdNetBind to fall
back to the standard library net package for all platforms other than
Linux.
Reviewed-by: James Tucker <[email protected]>
Signed-off-by: Jordan Whited <[email protected]>
Signed-off-by: Jason A. Donenfeld <[email protected]>
The conn.Bind UDP sockets' send and receive buffers are now being sized
to 7MB, whereas they were previously inheriting the system defaults.
The system defaults are considerably small and can result in dropped
packets on high speed links. By increasing the size of these buffers we
are able to achieve higher throughput in the aforementioned case.
The iperf3 results below demonstrate the effect of this commit between
two Linux computers with 32-core Xeon Platinum CPUs @ 2.9Ghz. There is
roughly ~125us of round trip latency between them.
The first result is from commit 792b49c which uses the system defaults,
e.g. net.core.{r,w}mem_max = 212992. The TCP retransmits are correlated
with buffer full drops on both sides.
Starting Test: protocol: TCP, 1 streams, 131072 byte blocks
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-10.00 sec 4.74 GBytes 4.08 Gbits/sec 2742 285 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
Test Complete. Summary Results:
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 4.74 GBytes 4.08 Gbits/sec 2742 sender
[ 5] 0.00-10.04 sec 4.74 GBytes 4.06 Gbits/sec receiver
The second result is after increasing SO_{SND,RCV}BUF to 7MB, i.e.
applying this commit.
Starting Test: protocol: TCP, 1 streams, 131072 byte blocks
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-10.00 sec 6.14 GBytes 5.27 Gbits/sec 0 3.15 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
Test Complete. Summary Results:
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 6.14 GBytes 5.27 Gbits/sec 0 sender
[ 5] 0.00-10.04 sec 6.14 GBytes 5.25 Gbits/sec receiver
The specific value of 7MB is chosen as it is the max supported by a
default configuration of macOS. A value greater than 7MB may further
benefit throughput for environments with higher network latency and
lower CPU clocks, but will also increase latency under load
(bufferbloat). Some platforms will silently clamp the value to other
maximums. On Linux, we use SO_{SND,RCV}BUFFORCE in case 7MB is beyond
net.core.{r,w}mem_max.
Co-authored-by: James Tucker <[email protected]>
Signed-off-by: James Tucker <[email protected]>
Signed-off-by: Jordan Whited <[email protected]>
Signed-off-by: Jason A. Donenfeld <[email protected]>
Implement TCP offloading via TSO and GRO for the Linux tun.Device, which
is made possible by virtio extensions in the kernel's TUN driver.
Delete conn.LinuxSocketEndpoint in favor of a collapsed conn.StdNetBind.
conn.StdNetBind makes use of recvmmsg() and sendmmsg() on Linux. All
platforms now fall under conn.StdNetBind, except for Windows, which
remains in conn.WinRingBind, which still needs to be adjusted to handle
multiple packets.
Also refactor sticky sockets support to eventually be applicable on
platforms other than just Linux. However Linux remains the sole platform
that fully implements it for now.
Co-authored-by: James Tucker <[email protected]>
Signed-off-by: James Tucker <[email protected]>
Signed-off-by: Jordan Whited <[email protected]>
Signed-off-by: Jason A. Donenfeld <[email protected]>
Accept packet vectors for reading and writing in the tun.Device and
conn.Bind interfaces, so that the internal plumbing between these
interfaces now passes a vector of packets. Vectors move untouched
between these interfaces, i.e. if 128 packets are received from
conn.Bind.Read(), 128 packets are passed to tun.Device.Write(). There is
no internal buffering.
Currently, existing implementations are only adjusted to have vectors
of length one. Subsequent patches will improve that.
Also, as a related fixup, use the unix and windows packages rather than
the syscall package when possible.
Co-authored-by: James Tucker <[email protected]>
Signed-off-by: James Tucker <[email protected]>
Signed-off-by: Jordan Whited <[email protected]>
Signed-off-by: Jason A. Donenfeld <[email protected]>
Jordan Whited