Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932396Ab0GOEvy (ORCPT ); Thu, 15 Jul 2010 00:51:54 -0400 Received: from mail-qw0-f46.google.com ([209.85.216.46]:54396 "EHLO mail-qw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932267Ab0GOEvw convert rfc822-to-8bit (ORCPT ); Thu, 15 Jul 2010 00:51:52 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=hf15lmndmau/fOwY70PFMMS/myWq/4H1QOafR4io78dYUcJXdVpq4mdz1vgBiDt3dz CJARPfD85jqp89zOSxrFmKNIssvXbDHqOvOgpOzUFMYVIPHTXBcOGHNrGL6Xp2uki1dw X/imY3CVpntnzbOLIDh5OdrfoUaO+FVJu8V+I= MIME-Version: 1.0 In-Reply-To: <20100714.111553.104052157.davem@davemloft.net> References: <4C3D94E3.9080103@wildgooses.com> <4C3DD5EB.9070908@tmr.com> <20100714.111553.104052157.davem@davemloft.net> Date: Wed, 14 Jul 2010 21:51:51 -0700 Message-ID: Subject: Re: Raise initial congestion window size / speedup slow start? From: "H.K. Jerry Chu" To: David Miller Cc: davidsen@tmr.com, lists@wildgooses.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1820 Lines: 43 On Wed, Jul 14, 2010 at 11:15 AM, David Miller wrote: > From: Bill Davidsen > Date: Wed, 14 Jul 2010 11:21:15 -0400 > >> You may have to go into /proc/sys/net/core and crank up the >> rmem_* settings, depending on your distribution. > > You should never, ever, have to touch the various networking sysctl > values to get good performance in any normal setup. ?If you do, it's a > bug, report it so we can fix it. Agreed, except there are indeed bugs in the code today in that the code in various places assumes initcwnd as per RFC3390. So when initcwnd is raised, that actual value may be limited unnecessarily by the initial wmem/sk_sndbuf. Will try to find time to submit a patch. Jerry > > I cringe every time someone says to do this, so please do me a favor > and don't spread this further. :-) > > For one thing, TCP dynamically adjusts the socket buffer sizes based > upon the behavior of traffic on the connection. > > And the TCP memory limit sysctls (not the core socket ones) are sized > based upon available memory. ?They are there to protect you from > situations such as having so much memory dedicated to socket buffers > that there is none left to do other things effectively. ?It's a > protective limit, rather than a setting meant to increase or improve > performance. ?So like the others, leave these alone too. > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at ?http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/