From mboxrd@z Thu Jan 1 00:00:00 1970 From: alekcejk@googlemail.com Subject: Re: Re: Re: Re: limited network bandwidth with 3.2.x kernels Date: Tue, 21 Feb 2012 20:53:51 +0200 Message-ID: <2389727.KTsXaHXfF4@localhost.localdomain> References: <8633039.fHPLx6GNq3@localhost.localdomain> <2604639.CVkfrWv5sk@localhost.localdomain> <1329845484.18384.20.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE To: Eric Dumazet , netdev@vger.kernel.org Return-path: Received: from mail-bk0-f46.google.com ([209.85.214.46]:35878 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755681Ab2BUSy0 convert rfc822-to-8bit (ORCPT ); Tue, 21 Feb 2012 13:54:26 -0500 Received: by bkcjm19 with SMTP id jm19so5625282bkc.19 for ; Tue, 21 Feb 2012 10:54:25 -0800 (PST) In-Reply-To: <1329845484.18384.20.camel@edumazet-laptop> Sender: netdev-owner@vger.kernel.org List-ID: =D0=92 =D1=81=D0=BE=D0=BE=D0=B1=D1=89=D0=B5=D0=BD=D0=B8=D0=B8 =D0=BE=D1= =82 =D0=92=D1=82=D0=BE=D1=80=D0=BD=D0=B8=D0=BA 21 =D1=84=D0=B5=D0=B2=D1= =80=D0=B0=D0=BB=D1=8F 2012 18:31:24 =D0=B2=D1=8B =D0=BD=D0=B0=D0=BF=D0=B8= =D1=81=D0=B0=D0=BB=D0=B8: > Le mardi 21 f=C3=A9vrier 2012 =C3=A0 19:19 +0200, alekcejk@googlemail= =2Ecom a >=20 > =C3=A9crit : > > Download speed from ftp3.de.freebsd.org increases from 5 MB/s to 10= MB/s > > after I set "sysctl net.ipv4.tcp_rmem=3D"4096 87380 4127616""" in 3= =2E2.7 kernel. > >=20 > > --2012-02-21 18:56:36-- ftp://ftp3.de.freebsd.org/pub/FreeBSD/ISO-= IMAGES-i386/8.2/FreeBSD-8.2-RELEASE-i386-dvd1.iso.xz > > 100%[=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D>] 2 066 424 512 10,= 3M/s in 3m 17s > > 2012-02-21 18:59:56 (9,99 MB/s) - =C2=AB/dev/null=C2=BB saved [2066= 424512] >=20 > Yep, this confirms the thing. You were at the limit of optimal receiv= er > window. Find a more remote server (80ms rtt for example) and you'll s= ee > that your default tcp_rmem[2] was too small, even on 3.1.10 kernel. I confirm that 3.1.10 kernel also have similar problems with speed. Download speed from dl.fedoraproject.org(209.132.181.24, rtt 190ms) increased after I set "sysctl net.ipv4.tcp_rmem=3D"4096 87380 4127616""= " If net.ipv4.tcp_rmem =3D 4096 87380 897664 then I have exactly=20 3.5 MB/s speed limitation: http://img3.imageshack.us/img3/28/netipv4tcprmem409687380.png --2012-02-21 20:25:10-- http://dl.fedoraproject.org/pub/fedora/linux/r= eleases/16/Fedora/i386/iso/Fedora-16-i386-DVD.iso 100%[=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D>] 3 806 375 936 3,28M/s in 20m 45s 2012-02-21 20:45:56 (2,92 MB/s) - =C2=AB/dev/null=C2=BB saved [38063759= 36/3806375936] But if net.ipv4.tcp_rmem =3D 4096 87380 4127616 no such limitation, download speed vary in some ranges but it can be larger than 3,5 MB/s: http://img27.imageshack.us/img27/28/netipv4tcprmem409687380.png --2012-02-21 20:09:56-- http://dl.fedoraproject.org/pub/fedora/linux/r= eleases/16/Fedora/i386/iso/Fedora-16-i386-DVD.iso 00%[=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D>] 3 806 375 936 4,65M/s im 13m 3s 2012-02-21 20:22:59 (4,64 MB/s) - =C2=AB/dev/null=C2=BB saved [38063759= 36/3806375936]