From owner-freebsd-hackers Tue Feb 27 12: 1:14 2001 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 BEB1737B71B for ; Tue, 27 Feb 2001 12:01:11 -0800 (PST) (envelope-from dcs@newsguy.com) Received: from newsguy.com (p14-dn01kiryunisiki.gunma.ocn.ne.jp [211.0.245.15]) by peach.ocn.ne.jp (8.9.1a/OCN/) with ESMTP id EAA19511; Wed, 28 Feb 2001 04:59:46 +0900 (JST) Message-ID: <3A9C0686.E4C80775@newsguy.com> Date: Wed, 28 Feb 2001 04:56:54 +0900 From: "Daniel C. Sobral" X-Mailer: Mozilla 4.7 [en] (Win98; I) X-Accept-Language: en,pt-BR MIME-Version: 1.0 To: Tony Finch Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Setting memory allocators for library functions. References: <200102260529.f1Q5T8413011@curve.dellroad.org> <200102260628.f1Q6SYX29811@earth.backplane.com> <3A9A0A9A.E4D31F97@newsguy.com> <200102261755.f1QHtvr34064@earth.backplane.com> <3A9AAB02.793A197A@newsguy.com> <200102261940.f1QJeJi38115@earth.backplane.com> <3A9B6548.E298F857@newsguy.com> <20010227194233.J609@hand.dotat.at> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Tony Finch wrote: > > >It doesn't trash. The memory is filled with backtracking information. > >Memory in active use at any time is rather small. > > I've read articles about programs which use GC which have a small > working set, although it is constantly changing (I've heard of > programs allocating megabytes a second). The OS would have to swap out > the stale pages if the program's total memory use exceeds RAM, and > when the GC finally runs it will take forever and thrash swap like > there's no tomorrow. It depends a lot on how allocation is made and the characteristics of the reachable objects graph. If the likeness of a reachable object existing in each page isn't small, it will trash indeed. On the other hand, if most objects created have very short lifetimes and a generational technique is used to move objects in the working set, then few pages of the swap will need to be swapped in for tracing, and the rest can be outright discarded without ever swaping them in. On the gripping hand, FreeBSD on configurations without swap is not unheard of by any means either, and overcommitting is still a problem in these configurations. -- Daniel C. Sobral (8-DCS) dcs@newsguy.com dcs@freebsd.org capo@the.obscure.bsdconspiracy.net I think you are delusional, but that is OK. Its part of your natural charm! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message