From owner-freebsd-current Wed Apr 14 6:30:44 1999 Delivered-To: freebsd-current@freebsd.org Received: from peach.ocn.ne.jp (peach.ocn.ne.jp [210.145.254.87]) by hub.freebsd.org (Postfix) with ESMTP id D6363157E0 for ; Wed, 14 Apr 1999 06:30:36 -0700 (PDT) (envelope-from dcs@newsguy.com) Received: from newsguy.com by peach.ocn.ne.jp (8.9.1a/OCN) id WAA27117; Wed, 14 Apr 1999 22:27:56 +0900 (JST) Message-ID: <3714925A.D348A0DB@newsguy.com> Date: Wed, 14 Apr 1999 22:04:26 +0900 From: "Daniel C. Sobral" X-Mailer: Mozilla 4.51 [en] (Win98; I) X-Accept-Language: pt-BR,ja MIME-Version: 1.0 To: Ladavac Marino Cc: "'mi@aldan.algebra.com'" , current@FreeBSD.ORG Subject: Re: swap-related problems References: <55586E7391ACD211B9730000C11002761795E9@r-lmh-wi-100.corpnet.at> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Transfer-Encoding: 7bit Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Ladavac Marino wrote: > > Another strategy is to reserve the swap space as soon as it is > allocated by the program. This strategy is much more conservative and > inherently safer, but it needs much more space: for instance, if you > have a program with WSS of a gigabyte and you want to system( "date" ), > you will need at least 2 gigs of swap because system() does fork() first > which means that you get 2 copies of your big program and the system > cannot know that in one of the copies an exec() will be shortly > forthcoming--thus, it has to reserve the full WSS for the copy because > it will potentially write to all pages of its WSS. > > It would be nice if memory overcommit were configurable (on-off, > or per process). On AIX, you can have it set as a global option and on/off per process. In my experience, though, setting it to off never solved anything: if you need memory, you have to add memory. -- Daniel C. Sobral (8-DCS) dcs@newsguy.com dcs@freebsd.org "nothing better than the ability to perform cunning linguistics" To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message