From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarek Poplawski Subject: Re: Linux 2.6.27.5 / SFQ/HTB scheduling problems Date: Fri, 14 Nov 2008 07:21:14 +0000 Message-ID: <20081114072114.GA4408@ff.dom.local> References: <20081113142958.36pzkmzwtxd3wbox@m.safari.iki.fi> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Sami Farin To: Linux Networking Mailing List Return-path: Received: from ug-out-1314.google.com ([66.249.92.173]:42463 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750799AbYKNHVV (ORCPT ); Fri, 14 Nov 2008 02:21:21 -0500 Received: by ug-out-1314.google.com with SMTP id 39so1566550ugf.37 for ; Thu, 13 Nov 2008 23:21:19 -0800 (PST) Content-Disposition: inline In-Reply-To: <20081113142958.36pzkmzwtxd3wbox@m.safari.iki.fi> Sender: netdev-owner@vger.kernel.org List-ID: On 13-11-2008 15:29, Sami Farin wrote: ... > Oh, I had old ethtool.. > These with v 6: > > # ethtool -k eth0 > Offload parameters for eth0: > rx-checksumming: off > tx-checksumming: off > scatter-gather: off > tcp segmentation offload: off > udp fragmentation offload: off > generic segmentation offload: on > > Wow. I turned gso off and now it works just like before. > No packets over size of mtu anymore, either. > > State Recv-Q Send-Q Local Address:Port Peer Address:Port > ESTAB 0 122334 80.223.84.180:57694 74.54.226.166:80 timer:(on,4.475ms,0) uid:518 ino:4546485 sk:2ea3ac80ffff8800 > ts sackcubic wscale:8,3 rto:4499 rtt:2914.12/378.5 cwnd:134 ssthresh:30 send 522.4Kbps rcv_space:5728 > > --- 84.250.192.1 ping statistics --- > 50 packets transmitted, 50 received, 0% packet loss, time 1877ms > rtt min/avg/max/mdev = 22.463/38.354/99.126/13.738 ms, pipe 3, ipg/ewma 38.309/34.963 ms > > ... >> Anyway these TSO/GSO/jumbo_frames are usually bad idea with packet >> schedulers (or need more tweaking - e.g. sfq quantum). > > Well this GSO on by default was an unexpected surprise for me, for sure. > > Maybe a warning on htb (or something) module load > "GSO enabled, everything might not work as expected, try > 'ethtool -K eth0 gso off' to turn GSO off"..? ;) I agree, such a warning could be useful. BTW, r2q == 1 in your config could harm latency too; if it's because of quantum warnings, usually (if there are big rate differences between classes) it's better to use htb class's "quantum" parameter (tc class add htb help). Jarek P. PS: it seems your mailer setting prevents adding your email as "To:" while doing "Reply All". Sometimes it's intended, but not the most popular on this list (e.g. I'd prefer to be "To/Cc-ed", because I'm not a subscriber at the moment).