From owner-freebsd-hackers Wed Aug 19 02:21:24 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id CAA15075 for freebsd-hackers-outgoing; Wed, 19 Aug 1998 02:21:24 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from mail.cs.tu-berlin.de (mail.cs.tu-berlin.de [130.149.17.13]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id CAA15063 for ; Wed, 19 Aug 1998 02:21:20 -0700 (PDT) (envelope-from wosch@cs.tu-berlin.de) Received: from caramba.cs.tu-berlin.de (wosch@caramba.cs.tu-berlin.de [130.149.17.12]) by mail.cs.tu-berlin.de (8.9.1/8.9.1) with ESMTP id LAA26652; Wed, 19 Aug 1998 11:18:13 +0200 (MET DST) Received: (from wosch@localhost) by caramba.cs.tu-berlin.de (8.9.1/8.9.0) id LAA24197; Wed, 19 Aug 1998 11:18:10 +0200 (MET DST) Message-ID: <19980819111809.A22887@caramba.cs.tu-berlin.de> Date: Wed, 19 Aug 1998 11:18:09 +0200 From: Wolfram Schneider To: Terry Lambert , Marc Slemko Cc: hackers@FreeBSD.ORG Subject: Re: sendfile() API? References: <199808171817.LAA06770@usr08.primenet.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <199808171817.LAA06770@usr08.primenet.com>; from Terry Lambert on Mon, Aug 17, 1998 at 06:17:34PM +0000 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On 1998-08-17 18:17:34 +0000, Terry Lambert wrote: > I have no doubt that it would be useful for static pages; I am just not > convinced that pushing the data over a call boundary is the real overhead > here. For an mmap'ed file, the only overhead is the copy from the VM > buffer to the mbuf. The only way such a call could eliminated this > overhead is by passing the VM buffers down as mbuf contents. This can > be done (I did the code for it on the VMS NetWare server), but it's > a lot of work. Who cares about data copy overhead? If the kernel spend 5% of the CPU time in copying, there are still 95% free CPU cycles. Freefall.freebsd.org transfers 20KB/s with a CPU load less than 0.01. http://www.freebsd.org/server-status Server uptime: 5 days 20 hours 26 minutes 44 seconds Total accesses: 1096361 - Total Traffic: 9.9 GB CPU Usage: u.859375 s.828125 cu1.96094 cs.304688 - .000782% CPU load 2.17 requests/sec - 20.6 kB/second - 9.5 kB/request -- Wolfram Schneider http://freebsd.org/~w/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message