From owner-freebsd-hackers Sat Mar 7 23:51:34 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id XAA21599 for freebsd-hackers-outgoing; Sat, 7 Mar 1998 23:51:34 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from dingo.cdrom.com (dingo.cdrom.com [204.216.28.145]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id XAA21587 for ; Sat, 7 Mar 1998 23:51:22 -0800 (PST) (envelope-from mike@dingo.cdrom.com) Received: from dingo.cdrom.com (localhost [127.0.0.1]) by dingo.cdrom.com (8.8.8/8.8.5) with ESMTP id XAA09061; Sat, 7 Mar 1998 23:48:53 -0800 (PST) Message-Id: <199803080748.XAA09061@dingo.cdrom.com> X-Mailer: exmh version 2.0zeta 7/24/97 To: Julian Elischer cc: Marc Slemko , Mike Smith , hackers@FreeBSD.ORG Subject: Re: kernel wishlist for web server performance In-reply-to: Your message of "Sat, 07 Mar 1998 23:16:43 PST." Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Sat, 07 Mar 1998 23:48:52 -0800 From: Mike Smith Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > I would like to add here that in FreeBSD's unified VM/Buffer cache, > a mmapped file IS the buffer cache > so that a send() from an mmapped file IS copying direct fromt he buffer > cache. Ther eis ONE copy.. that from the buffer cache, into the mbuf. > > (assuming that the data got into the memory via DMA in the first place..) > you may need to have a subprocess go through and tuch all the pages to > get them into ram first.. The copyin will do this. This is why I couldn't see a real performance benefit outside of the convenience factor, and the mbuf shuffling alluded to. -- \\ Sometimes you're ahead, \\ Mike Smith \\ sometimes you're behind. \\ mike@smith.net.au \\ The race is long, and in the \\ msmith@freebsd.org \\ end it's only with yourself. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message