From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexei Starovoitov Subject: Re: [PATCH v2 net-next] net: sched: run ingress qdisc without locks Date: Mon, 04 May 2015 18:27:36 -0700 Message-ID: <55481C88.2000007@plumgrid.com> References: <1430544448-19777-1-git-send-email-ast@plumgrid.com> <20150503174208.5b1548ba@redhat.com> <5546FFCB.50903@plumgrid.com> <20150504130405.3ff6672e@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: "David S. Miller" , John Fastabend , Jamal Hadi Salim , Daniel Borkmann , netdev@vger.kernel.org To: Jesper Dangaard Brouer Return-path: Received: from mail-pd0-f173.google.com ([209.85.192.173]:34754 "EHLO mail-pd0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751068AbbEEB1i (ORCPT ); Mon, 4 May 2015 21:27:38 -0400 Received: by pdbqa5 with SMTP id qa5so178846288pdb.1 for ; Mon, 04 May 2015 18:27:37 -0700 (PDT) In-Reply-To: <20150504130405.3ff6672e@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On 5/4/15 4:04 AM, Jesper Dangaard Brouer wrote: > > How do you activate the ingress code path? > > I'm just doing (is this enough?): > export DEV=eth4 > tc qdisc add dev $DEV handle ffff: ingress yes. plus my numbers also include u32 classifier. > I re-ran the experiment, and I can also only show a 2.68ns > improvement. This is rather strange, and I cannot explain it. > > The lock clearly shows up in perf report[1] with 12.23% raw_spin_lock, > and perf report[2] it clearly gone, but we don't see a 12% improvement > in performance, but around 4.7%. It's indeed puzzling. Hopefully intel experts can chime in. > The "cost" of activating the ingress qdisc is also interesting: > (1/25398057*10^9)-(1/16989315*10^9) = -19.49 ns > (1/25398057*10^9)-(1/17800496*10^9) = -16.81 ns yep, we're working hard on reducing it. btw the cost of enabling rps without using it is ~8ns. Our line rate goal is still a bit far, but hopefully getting closer :)