From owner-freebsd-hackers Wed Jul 14 21:54: 2 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from peach.ocn.ne.jp (peach.ocn.ne.jp [210.145.254.87]) by hub.freebsd.org (Postfix) with ESMTP id CF4331504C for ; Wed, 14 Jul 1999 21:53:55 -0700 (PDT) (envelope-from dcs@newsguy.com) Received: from newsguy.com by peach.ocn.ne.jp (8.9.1a/OCN) id NAA28999; Thu, 15 Jul 1999 13:53:50 +0900 (JST) Message-ID: <378D64F5.5AA2CC5F@newsguy.com> Date: Thu, 15 Jul 1999 13:35:01 +0900 From: "Daniel C. Sobral" X-Mailer: Mozilla 4.6 [en] (Win98; I) X-Accept-Language: pt-BR,ja MIME-Version: 1.0 To: John Nemeth Cc: freebsd-hackers@FreeBSD.ORG, tech-userlevel@netbsd.org Subject: Re: Swap overcommit (was Re: Replacement for grep(1) (part 2)) References: <199907141753.KAA02096@vtn1.victoria.tc.ca> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG John Nemeth wrote: > > On one system I administrate, the largest process is typically > rpc.nisd (the NIS+ server daemon). Killing that process would be a > bad thing (TM). You're talking about killing random processes. This > is no way to run a system. It is not possible for any arbitrary > decision to always hit the correct process. That is a decision that > must be made by a competent admin. This is the biggest argument > against overcommit: there is no way to gracefully recover from an > out of memory situation, and that makes for an unreliable system. If you run out of memory, it is either a misconfigured system, or a runaway program. If a program is runaway, then: 1) It is larger than your typical rpc.nisd. 2) You cannot tell the system a priori to kill it, because you don't know about it (or else, you wouldn't be running it in first place). A system running in overcommit assumes that you have it correctly configured so it will *not* run out of memory under normal conditions. This happens to be the same assumption Unix does. -- Daniel C. Sobral (8-DCS) dcs@newsguy.com dcs@freebsd.org "Would you like to go out with me?" "I'd love to." "Oh, well, n... err... would you?... ahh... huh... what do I do next?" To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message