From owner-freebsd-hackers Tue Oct 31 8: 9:33 2000 Delivered-To: freebsd-hackers@freebsd.org Received: from earth.backplane.com (placeholder-dcat-1076843399.broadbandoffice.net [64.47.83.135]) by hub.freebsd.org (Postfix) with ESMTP id 24E5A37B4C5 for ; Tue, 31 Oct 2000 08:09:32 -0800 (PST) Received: (from dillon@localhost) by earth.backplane.com (8.11.1/8.9.3) id e9VG8SU18725; Tue, 31 Oct 2000 08:08:28 -0800 (PST) (envelope-from dillon) Date: Tue, 31 Oct 2000 08:08:28 -0800 (PST) From: Matt Dillon Message-Id: <200010311608.e9VG8SU18725@earth.backplane.com> To: Peter Dufault Cc: Terry Lambert , Ryan Thompson , freebsd-hackers@FreeBSD.ORG Subject: Re: Filesystem holes References: <200010311235.HAA31834@hda.hda.com> Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG :In my case I'd be better off with shared memory objects that aren't :persistent but appear in the name space so that I don't accidentally :start copying a virtual bus file when the programs exit improperly. :In the sparse matrix calculations with no checkpointing or need to appear :in a name space I'd think the best thing would be to use VM with the matrix :initially mapped to a copy on write zero page. I guess you can't :do that without mmap because of swap allocation. : :Peter : :-- :Peter Dufault (dufault@hda.com) Realtime development, Machine control, If you can fit the whole thing into a process's VM space, then you can certainly use mmap(...MAP_ANON...) combined with madvise(... MADV_FREE) to implement a sparse memory object. There was talk a while ago about feeding MADV_FREE through to the filesystem layer. I was under the impression that SUN does that, does anyone know? -Matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message