From: "Richard B. Johnson" <root@chaos.analogic.com> Date: Mon, 7 Oct 2002 09:12:13 -0400 (EDT) If you log-in over the network, so that a socket is being used, it will print HELP!!!!!!! continuously on the screen because it is continually being signalled that I/O is possible instead of being signaled only when things change. First, 2.4.19 did not change the SIGIO behavior of TCP. Second, SIGIO is sent any time new write/read space is made available and that space exceeds some "wakeup threshold". SIGIO is also sent when an error condition is created. This is necessary to avoid races and has been the algorithm for some time in 2.3.x/2.4.x Any "chatty" protocol like telnet or sshd is going to generate a ton of SIGIO's for POLL_OUT especially. Chatty protocols should not make use of SIGIO for this reason if they care about performance. Third, your program is buggy because what you're getting SIGIO's for is POLL_OUT or POLL_ERR, checking only POLL_IN is insufficient. Every time a write goes out the socket, or an ACK is finished being transmitted by a device, socket write space is recovered and a SIGIO is going to go out if the write space exceeds some threshold. This behavior is not a bug. - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
