From owner-freebsd-stable Fri May 4 9:12: 1 2001 Delivered-To: freebsd-stable@freebsd.org Received: from earth.backplane.com (earth-nat-cw.backplane.com [208.161.114.67]) by hub.freebsd.org (Postfix) with ESMTP id 6A39437B422 for ; Fri, 4 May 2001 09:11:59 -0700 (PDT) (envelope-from dillon@earth.backplane.com) Received: (from dillon@localhost) by earth.backplane.com (8.11.2/8.11.2) id f44GAmr25737; Fri, 4 May 2001 09:10:48 -0700 (PDT) (envelope-from dillon) Date: Fri, 4 May 2001 09:10:48 -0700 (PDT) From: Matt Dillon Message-Id: <200105041610.f44GAmr25737@earth.backplane.com> To: Cy Schubert - ITSD Open Systems Group Cc: freebsd-stable@FreeBSD.ORG Subject: Re: Mem Use References: <200105040028.f440SoI16925@cwsys.cwsent.com> Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG :All this talk of memory utilisation reminds me to ask, are there any :plans to implement directio (Solaris UFS and VxFS have it)? There has been talk. It's considered 'interesting' but it is not a priority. FreeBSD's heuristics already handle write-behind and free-behind operations so, for example, writing out a 200MB file sequentially will not blow away your cache. :Any plans to implement priority paging, e.g. not cache files in memory :when memory is tight to reduce demand for paging? The VM system already tunes itself to load. It's not as simple as deciding whether to cache something or not... *everything* in the system is part of the cache. It's a matter of balancing demand and determining when to lunder dirty pages to their backing store. Anything that isn't dirty is potentially freeable whether it represents (cached) files, code, data, or anonymous memory. But gratuitously throwing away file cache pages will kill performance as quickly as gratuitously throwing away swapped out anonymous memory. -Matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message