device: change Peer.endpoint locking to reduce contention
Access to Peer.endpoint was previously synchronized by Peer.RWMutex. This has now moved to Peer.endpoint.Mutex. Peer.SendBuffers() is now the sole caller of Endpoint.ClearSrc(), which is signaled via a new bool, Peer.endpoint.clearSrcOnTx. Previous Callers of Endpoint.ClearSrc() now set this bool, primarily via peer.markEndpointSrcForClearing(). Peer.SetEndpointFromPacket() clears Peer.endpoint.clearSrcOnTx when an updated conn.Endpoint is stored. This maintains the same event order as before, i.e. a conn.Endpoint received after peer.endpoint.clearSrcOnTx is set, but before the next Peer.SendBuffers() call results in the latest conn.Endpoint source being used for the next packet transmission. These changes result in throughput improvements for single flow, parallel (-P n) flow, and bidirectional (--bidir) flow iperf3 TCP/UDP tests as measured on both Linux and Windows. Latency under load improves especially for high throughput Linux scenarios. These improvements are likely realized on all platforms to some degree, as the changes are not platform-specific. Co-authored-by: James Tucker <james@tailscale.com> Signed-off-by: James Tucker <james@tailscale.com> Signed-off-by: Jordan Whited <jordan@tailscale.com> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
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committed by
Jason A. Donenfeld
parent
d0bc03c707
commit
4ffa9c2032
@@ -100,11 +100,7 @@ func expiredRetransmitHandshake(peer *Peer) {
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peer.device.log.Verbosef("%s - Handshake did not complete after %d seconds, retrying (try %d)", peer, int(RekeyTimeout.Seconds()), peer.timers.handshakeAttempts.Load()+1)
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/* We clear the endpoint address src address, in case this is the cause of trouble. */
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peer.Lock()
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if peer.endpoint != nil {
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peer.endpoint.ClearSrc()
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}
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peer.Unlock()
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peer.markEndpointSrcForClearing()
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peer.SendHandshakeInitiation(true)
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}
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@@ -123,11 +119,7 @@ func expiredSendKeepalive(peer *Peer) {
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func expiredNewHandshake(peer *Peer) {
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peer.device.log.Verbosef("%s - Retrying handshake because we stopped hearing back after %d seconds", peer, int((KeepaliveTimeout + RekeyTimeout).Seconds()))
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/* We clear the endpoint address src address, in case this is the cause of trouble. */
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peer.Lock()
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if peer.endpoint != nil {
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peer.endpoint.ClearSrc()
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}
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peer.Unlock()
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peer.markEndpointSrcForClearing()
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peer.SendHandshakeInitiation(false)
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}
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