fix: increases DERP send queue length to 512 for increased throughput

spikecurtis · spikecurtis · commit 7c2c1ea4459e · 2024-05-30T10:51:18.000+04:00
Signed-off-by: Spike Curtis &lt;spike@coder.com&gt;
diff --git a/derp/derp_server.go b/derp/derp_server.go
@@ -70,7 +70,13 @@ func init() {
 }
 
 const (
-	perClientSendQueueDepth = 32 // packets buffered for sending
+	// perClientSendQueueDepth is the number of packets to buffer for sending.
+	// CODER: We've modified this to 512, up from 32 in upstream Tailscale to improve DERP
+	// throughput.  32 is an understandable number for big, public DERP servers that Tailscale run,
+	// serving many thousands of connections, and where Tailscale is footing the bill.  In Coder's
+	// use case, we are serving hundreds to low thousands of users and the user's own company is
+	// paying the bills.  In testing, it increases DERP throughput up to 6x.
+	perClientSendQueueDepth = 512
 	writeTimeout            = 2 * time.Second
 )
 

Original file line number	Diff line number	Diff line change
`@@ -70,7 +70,13 @@ func init() {`
`70`	`70`	`}`
`71`	`71`
`72`	`72`	`const (`
`73`		`- perClientSendQueueDepth = 32 // packets buffered for sending`
	`73`	`+ // perClientSendQueueDepth is the number of packets to buffer for sending.`
	`74`	`+ // CODER: We've modified this to 512, up from 32 in upstream Tailscale to improve DERP`
	`75`	`+ // throughput. 32 is an understandable number for big, public DERP servers that Tailscale run,`
	`76`	`+ // serving many thousands of connections, and where Tailscale is footing the bill. In Coder's`
	`77`	`+ // use case, we are serving hundreds to low thousands of users and the user's own company is`
	`78`	`+ // paying the bills. In testing, it increases DERP throughput up to 6x.`
	`79`	`+ perClientSendQueueDepth = 512`
`74`	`80`	`writeTimeout = 2 * time.Second`
`75`	`81`	`)`
`76`	`82`