From owner-freebsd-current Tue Aug 25 21:20:50 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id VAA05773 for freebsd-current-outgoing; Tue, 25 Aug 1998 21:20:50 -0700 (PDT) (envelope-from owner-freebsd-current@FreeBSD.ORG) Received: from smtp04.primenet.com (smtp04.primenet.com [206.165.6.134]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id VAA05768; Tue, 25 Aug 1998 21:20:44 -0700 (PDT) (envelope-from tlambert@usr07.primenet.com) Received: (from daemon@localhost) by smtp04.primenet.com (8.8.8/8.8.8) id VAA17907; Tue, 25 Aug 1998 21:19:51 -0700 (MST) Received: from usr07.primenet.com(206.165.6.207) via SMTP by smtp04.primenet.com, id smtpd017888; Tue Aug 25 21:19:47 1998 Received: (from tlambert@localhost) by usr07.primenet.com (8.8.5/8.8.5) id VAA01004; Tue, 25 Aug 1998 21:19:40 -0700 (MST) From: Terry Lambert Message-Id: <199808260419.VAA01004@usr07.primenet.com> Subject: Re: Threads across processors To: ben@rosengart.com Date: Wed, 26 Aug 1998 04:19:40 +0000 (GMT) Cc: tlambert@primenet.com, mike@smith.net.au, michaelh@cet.co.jp, gpalmer@FreeBSD.ORG, chuckr@glue.umd.edu, freebsd-current@FreeBSD.ORG In-Reply-To: from "Snob Art Genre" at Aug 25, 98 10:23:47 pm X-Mailer: ELM [version 2.4 PL25] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > > A dirty little secret is that SYSV SHM in FreeBSD is much faster > > than mmap, because pages backed by anonymous pages instead of a > > vnode pager object do not have to be written through... > > What about this? From mmap(2): > > MAP_ANON Map anonymous memory not associated with any specific file. > The file descriptor used for creating MAP_ANON must be -1. > The offset parameter is ignored. Memory mapped this way can only be shared between a parent process and children, and then only if marked for inheritance. This is a hell of a lot less useful that SYSV SHM, especially if the memory is to be attached by a non-child process for the purpose of status reporting and/or control (for example). Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message