From owner-cvs-src-old@FreeBSD.ORG  Sun Mar 15 20:23:25 2009
Return-Path: <owner-cvs-src-old@FreeBSD.ORG>
Delivered-To: cvs-src-old@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id EC1221065678
	for <cvs-src-old@freebsd.org>; Sun, 15 Mar 2009 20:23:25 +0000 (UTC)
	(envelope-from rwatson@FreeBSD.org)
Received: from repoman.freebsd.org (repoman.freebsd.org
	[IPv6:2001:4f8:fff6::29])
	by mx1.freebsd.org (Postfix) with ESMTP id D95DC8FC12
	for <cvs-src-old@freebsd.org>; Sun, 15 Mar 2009 20:23:25 +0000 (UTC)
	(envelope-from rwatson@FreeBSD.org)
Received: from repoman.freebsd.org (localhost [127.0.0.1])
	by repoman.freebsd.org (8.14.3/8.14.3) with ESMTP id n2FKNPDp065451
	for <cvs-src-old@freebsd.org>; Sun, 15 Mar 2009 20:23:25 GMT
	(envelope-from rwatson@repoman.freebsd.org)
Received: (from svn2cvs@localhost)
	by repoman.freebsd.org (8.14.3/8.14.3/Submit) id n2FKNPbD065450
	for cvs-src-old@freebsd.org; Sun, 15 Mar 2009 20:23:25 GMT
	(envelope-from rwatson@repoman.freebsd.org)
Message-Id: <200903152023.n2FKNPbD065450@repoman.freebsd.org>
X-Authentication-Warning: repoman.freebsd.org: svn2cvs set sender to
	rwatson@repoman.freebsd.org using -f
From: Robert Watson <rwatson@FreeBSD.org>
Date: Sun, 15 Mar 2009 20:17:44 +0000 (UTC)
To: cvs-src-old@freebsd.org
X-FreeBSD-CVS-Branch: HEAD
Subject: cvs commit: src/share/man/man4 lo.4 src/sys/net if_loop.c
X-BeenThere: cvs-src-old@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: **OBSOLETE** CVS commit messages for the src tree
	<cvs-src-old.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/cvs-src-old>,
	<mailto:cvs-src-old-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/cvs-src-old>
List-Post: <mailto:cvs-src-old@freebsd.org>
List-Help: <mailto:cvs-src-old-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/cvs-src-old>,
	<mailto:cvs-src-old-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sun, 15 Mar 2009 20:23:26 -0000

rwatson     2009-03-15 20:17:44 UTC

  FreeBSD src repository

  Modified files:
    share/man/man4       lo.4 
    sys/net              if_loop.c 
  Log:
  SVN rev 189863 on 2009-03-15 20:17:44Z by rwatson
  
  Teach the loopback interface about checksum generation and validation
  avoidance:
  
  - Enable setting the RXCSUM and TXCSUM flags for loopback interfaces;
    set both by default.
  - When RXCSUM is set, flag packets sent over the loopback interface as
    having checked and valid IP, UDP, TCP checksums so that higher
    protocol layers won't check them.
  - Always clear CSUM_{IP,UDP_TCP} checksum required flags on transmit,
    as they will have gotten there as a result of TXCSUM being set.
  
  This is done only for packets explicitly sent over the loopback, not
  simulated loopback via if_simloop() due to !SIMPLEX interfaces, etc.
  
  Note that enabling TXCSUM but not RXCSUM will lead to unhappiness, as
  checksums won't be generated but will be validated.
  
  Kris reports that this leads to significant performance improvements
  in loopback benchmarking with TCP and UDP for throughput:
  
          RXCSUM  RXCSUM+TXCSUM
  TCP     15%     37%
  UDP     10%     74%
  
  Update man page.
  
  Reviewed by:    sam
  Tested by:      kris
  MFC after:      1 week
  
  Revision  Changes    Path
  1.10      +21 -12    src/share/man/man4/lo.4
  1.126     +22 -1     src/sys/net/if_loop.c