CSvax:Physics:crl (09/21/82)
#R:sri-unix:-327500:pur-phy:12700001:000:1104 pur-phy!crl Sep 20 14:49:00 1982 We have also found that long unterminated tty lines can really hang a system. In fact, we have had to do more than just keep the sleep/flush code in. What we ended up doing was also checking for a large percentage of non-printing characters in the username or password replies in login. Too many and the line is set to no-echo and kept inactive for one minute. The reason why we went through all this bother was that some of these ttys were getting in a very active "feedback" loop, causing about 1000 chars/sec input to our 11/44, and about one init/getty/login every few seconds. This really brought the system to its knees (it took su running at nice 10 about 10 minutes to bring up a shell just so we could tell what was going on). As an aside, here is one case for having a FAST su, like the one that discussion raged about earlier (I hope I haven't started a repeat performance). Since we couldn't get anything to run very fast without being su at nice 0, we were basically helpless until the su shell managed to get enough cpu. Charles LaBrec Physics Dept. Purdue Univ. pur-ee!physics:crl