From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jamal Hadi Salim Subject: Re: [net-next PATCH V5] qdisc: bulk dequeue support for qdiscs with TCQ_F_ONETXQUEUE Date: Wed, 01 Oct 2014 09:17:39 -0400 Message-ID: <542BFEF3.7020302@mojatatu.com> References: <20140930085114.24043.81310.stgit@dragon> <542A8EF9.10403@mojatatu.com> <20140930.142038.235338672810639160.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: brouer@redhat.com, netdev@vger.kernel.org, therbert@google.com, eric.dumazet@gmail.com, hannes@stressinduktion.org, fw@strlen.de, dborkman@redhat.com, alexander.duyck@gmail.com, john.r.fastabend@intel.com, dave.taht@gmail.com, toke@toke.dk To: David Miller Return-path: Received: from mail-ig0-f179.google.com ([209.85.213.179]:40660 "EHLO mail-ig0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751053AbaJANRr (ORCPT ); Wed, 1 Oct 2014 09:17:47 -0400 Received: by mail-ig0-f179.google.com with SMTP id h18so277317igc.12 for ; Wed, 01 Oct 2014 06:17:46 -0700 (PDT) In-Reply-To: <20140930.142038.235338672810639160.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On 09/30/14 14:20, David Miller wrote: > From: Jamal Hadi Salim > Date: Tue, 30 Sep 2014 07:07:37 -0400 > >> Note, there are benefits as you have shown - but i would not >> consider those to be standard use cases (actully one which would >> have shown clear win is the VM thing Rusty was after). > > I completely disagree, you will see at least decreased cpu utilization > for a very common case, bulk single stream transfers. > So lets say the common use case is: = modern day cpu (pick some random cpu) = 1-10 Gbps ethernet (not 100mbps) = 1-24 tcp or udp bulk (you said one, Jesper had 24 which sounds better) Run with test cases: a) unchanged (no bulking code added at all) vs b) bulking code added and used vs c) bulking code added and *not* used Jesper's results are comparing #b and #c. And if #b + #c are slightly worse or equal then we have a win;-> Again, I do believe things like traffic generators or the VM io or something like tuntap that crosses user space will have a clear benefit (but are those common use cases?). cheers, jamal