Again: TCP server performance completely unuseful #1430
Description
Hi, I'm sorry to bring this up once more as it has been referenced several times now. But still, I cannot get a TCP server to put more than one packet in the send queue due to incorrect handling of the delayed ACK. Looking at the headers, there is the TCP_MSS set to 1460 and the TCP_WND four times that value. Hence, if the same thing is in the liblwip.a (and negotiation works correctly), we shouldn't have a problem.
What bothers me in particular is the following video https://www.youtube.com/watch?v=8ISbmQTbjDI where this guy sends websocket replies back to the client at about 220Hz. And they carry arrays of data. To be fair, he coded this with the FreeRTOS version without arduino intermediary layer.
BUT: why can't we have this?
WiFiServer tcpTelnetServer(23);
WiFiClient tcpTelnetClient; // Only one client at a time a.t.m.!
void setup() {
tcpTelnetServer.begin();
}
void loop() {
// HANDLE TCP TELNET SERVER
if (!tcpTelnetClient.connected()) {
tcpTelnetClient = tcpTelnetServer.available();
if (tcpTelnetClient.connected()) {
tcpTelnetClient.setNoDelay(true);
Serial.println(" DBG: New TCP client connected...");
}
} else {
// remember: Telnet sends \r or \r\n, NOT \n!
if (tcpTelnetClient.available()) {
char stringBuffer[300];
tcpTelnetClient.readBytesUntil('\r', stringBuffer, sizeof(stringBuffer)-1);
tcpTelnetClient.flush();
// Process command...
for (int i=0; i<6; i++) {
memset(stringBuffer, 't', 60);
stringBuffer[60] = 0; // Zeroterminate manually!
Serial.printf("Before (%d): %d\n", i, micros());
tcpTelnetClient.print(stringBuffer);
Serial.printf("Middle (%d): %d\n", i, micros());
tcpTelnetClient.write((uint8_t *)stringBuffer, strlen(stringBuffer));
Serial.printf("After (%d): %d\n\n", i, micros());
}
}
}
}this results in
Before (0): 46582971
Middle (0): 46785297
After (0): 46984893
Before (1): 46985136
Middle (1): 47393106
After (1): 47803031
Before (2): 47803275
Middle (2): 48212294
After (2): 48621882
Before (3): 48622126
Middle (3): 48827013
After (3): 49236314
Before (4): 49236558
Middle (4): 49647626
After (4): 49854952
Before (5): 49855141
Middle (5): 50054827
After (5): 50254701
*edit: MWE added..