From mboxrd@z Thu Jan 1 00:00:00 1970 From: alekcejk@googlemail.com Subject: Re: Re: Re: Re: Re: Re: Re: Re: Re: limited network bandwidth with 3.2.x kernels Date: Wed, 15 Feb 2012 17:05:36 +0200 Message-ID: <2414604.1vsFa6H21P@localhost.localdomain> References: <8633039.fHPLx6GNq3@localhost.localdomain> <2687521.3ztN17SHUf@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=koi8-r Content-Transfer-Encoding: QUOTED-PRINTABLE To: Neal Cardwell , netdev@vger.kernel.org Return-path: Received: from mail-bk0-f46.google.com ([209.85.214.46]:62439 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751034Ab2BOPFv convert rfc822-to-8bit (ORCPT ); Wed, 15 Feb 2012 10:05:51 -0500 Received: by bkcjm19 with SMTP id jm19so1015960bkc.19 for ; Wed, 15 Feb 2012 07:05:50 -0800 (PST) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: =F7 =D3=CF=CF=C2=DD=C5=CE=C9=C9 =CF=D4 =F3=D2=C5=C4=C1 15 =C6=C5=D7=D2=C1= =CC=D1 2012 09:49:07 =D7=D9 =CE=C1=D0=C9=D3=C1=CC=C9: > If there was an increase in the number of bytes charged to the socket > for each skb, without a corresponding increase in TCP receive buffer > size, that would explain a systematic decrease in receiver window tha= t > would cause some paths, like perhaps these, to become > receiver-window-limited (which is consistent with the symptom of > stable bandwidth for a given path). >=20 > Can you please try increasing the default TCP receiver window to see > if this helps; try this as root on the 3.2 machine: >=20 > sysctl net.ipv4.tcp_rmem=3D"4096 897664 897664" The same results after setting this. >=20 > Basically making the middle number as big as the third number should > bump up the default receiver window size. >=20 > neal