From mboxrd@z Thu Jan 1 00:00:00 1970 From: jamal Subject: Re: [e1000 2.6 10/11] TxDescriptors -> 1024 default Date: 15 Sep 2003 08:12:08 -0400 Sender: netdev-bounce@oss.sgi.com Message-ID: <1063627928.1075.66.camel@jzny.localdomain> References: <3F60CA6D.9090503@pobox.com> <3F60D0F3.8080006@candelatech.com> <20030911131219.0ab8dfdd.davem@redhat.com> <3F60DDCC.5020906@candelatech.com> <20030911140746.4f0384a1.davem@redhat.com> <3F60E947.4090005@candelatech.com> <20030911142906.74d9dfe5.davem@redhat.com> <3F60F3F7.6090203@candelatech.com> <20030911160252.6cd6c07d.davem@redhat.com> <3F6103BB.5030706@candelatech.com> <1063330463.1028.8.camel@jzny.localdomain> <20030912204947.5267e3aa.davem@redhat.com> <16227.1284.893748.365713@robur.slu.se> Reply-To: hadi@cyberus.ca Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: "David S. Miller" , greearb@candelatech.com, jgarzik@pobox.com, scott.feldman@intel.com, netdev@oss.sgi.com, ricardoz@us.ibm.com Return-path: To: Robert Olsson In-Reply-To: <16227.1284.893748.365713@robur.slu.se> Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org On Sat, 2003-09-13 at 07:52, Robert Olsson wrote: > > > > I spoke with Alexey once about this, actually tx_queue_len can > > be arbitrarily large but it should be reasonable nonetheless. > > > > Our preliminary conclusions were that values of 1000 for 100Mbit and > > faster were probably appropriate. Maybe something larger for 1Gbit, > > who knows. If you recall we saw that even for the gent who was trying to do 100K TCP sockets on a 4 way SMP, 1000 was sufficient and no packets were dropped. > > > > We also determined that the only connection between TX descriptor > > ring size and dev->tx_queue_len was that the latter should be large > > enough to handle, at a minimum, the amount of pending TX descriptor > > ACKs that can be pending considering mitigation et al. > > > > So if TX irq mitigation can defer up to N TX descriptor completions > > then dev->tx_queue_len must be at least that large. > > > > Back to the main topic, maybe we should set dev->tx_queue_len to > > 1000 by default for all ethernet devices. > > Hello! > > Yes sounds like adequate setting for GIGE. This is what use for production > and lab but rather than increasing dev->tx_queue_len to 1000 we replace the > pfifo_fast with the pfifo qdisc w. setting a qlen of 1000. > I think this may not be good for the reason of QoS. You want BGP packets to be given priority over ftp. A single queue kills that. The current default 3 band queue is good enough, the only challenge being noone sees stats for it. I have a patch for the kernel at: http://www.cyberus.ca/~hadi/patches/restore.pfifo.kernel and for tc at: http://www.cyberus.ca/~hadi/patches/restore.pfifo.tc cheers, jamal