Path: utzoo!utgpu!watmath!att!tut.cis.ohio-state.edu!ucbvax!GARNET.BERKELEY.EDU!rusty From: rusty@GARNET.BERKELEY.EDU Newsgroups: comp.unix.ultrix Subject: Process scheduling - how does it work. Message-ID: <8908150138.AA24829@garnet.berkeley.edu> Date: 15 Aug 89 01:38:41 GMT Sender: daemon@ucbvax.BERKELEY.EDU Lines: 13 The renicing of long running processes is a crude hack put in by the Berkeley people in 4bsd to attempt to improve interactive response at the expense of cpu intensive programs which at that time on their system probably consisted of troff jobs and such. The algorithm in 4bsd is essentially "if the process isn't being run by root and its niceness isn't between 0 and 4 then renice it to 4." Therefore, you can either renice it to some negative value (-1 for example) or 1, 2, or 3, or have root start it. Remember that niceness only affects things when more than 1 process is running (R under the STAT column from the output of ps; all the others don't count for the most part). If only 1 process is running and it's at nice 20 it runs at full spead (i.e., it gets 100% of the cpu).