Date: Fri, 25 Jun 1999 17:20:43 +0200 (MET DST) From: Thomas Schuerger <schuerge@wjpserver.CS.Uni-SB.DE> To: "Jose M. Alcaide" <jose@we.lc.ehu.es> Cc: sheldonh@FreeBSD.ORG, schuerge@cs.uni-sb.de, freebsd-bugs@FreeBSD.ORG Subject: Re: kern/12381: Bad scheduling in FreeBSD Message-ID: <199906251520.RAA20043@wjpserver.cs.uni-sb.de> In-Reply-To: <3773958A.7F6F2818@we.lc.ehu.es> from "Jose M. Alcaide" at "Jun 25, 1999 04:43:22 pm"
next in thread | previous in thread | raw e-mail | index | archive | help
> Here we are using several FreeBSD systems for running CPU-intensive > processes (now including some "setiathome's" ;-) ). All these processes > run with nice 20, and their impact in general system performance is > very low. In other words, we are not experiencing that performance > degradation. Of course, a process which is CPU-bound and also a memory > hog has a noticeable impact on performance (due to paging and swapping). Well, please do a test that transfers heavily over the network or that does a lot of disk I/O, once when setathome is running and once when it's not. Heavy disk I/O will also be slower, try updating your ports or your source tree via cvsup and measure times to do so. A friend of mine has the same problem as I do. > However, what I see is that the nice number has little influence on > the priority of CPU-bound processes. I think that is due to the way > 4.4BSD uses for computing the instant scheduling priority: the recent > CPU usage causes a quick degradation of priority. Then, two CPU-intensive > processes, one running with nice 5, and another with nice 20, will > have the same scheduling priority a few seconds after they start. > This does not happen with other UNIXes; for example, two identical > processes running with nice 9 and 19 on Solaris, get the 65% and 30% > of CPU respectively. Using FreeBSD, both processes get the 50% of > the CPU. Yes, that's true. It may be a small change in the scheduling, but I think it's important that someone has a look at it. Ciao, Thomas. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199906251520.RAA20043>