From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarek Poplawski Subject: Re: [PATCH v4 1/1] rps: core implementation Date: Sat, 21 Nov 2009 01:40:11 +0100 Message-ID: <4B0736EB.8090406@gmail.com> References: <65634d660911201528k5a07135el471b65fff9dd7c9d@mail.gmail.com> <20091120.153913.242783116.davem@davemloft.net> <65634d660911201550v34bc463ao17dcd7b16f62264f@mail.gmail.com> <20091120.160507.110482370.davem@davemloft.net> <65634d660911201612y12a9b5bnb6685da040ad832d@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: David Miller , netdev@vger.kernel.org To: Tom Herbert Return-path: Received: from mail-bw0-f227.google.com ([209.85.218.227]:53531 "EHLO mail-bw0-f227.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753779AbZKUAkc (ORCPT ); Fri, 20 Nov 2009 19:40:32 -0500 Received: by bwz27 with SMTP id 27so3856080bwz.21 for ; Fri, 20 Nov 2009 16:40:37 -0800 (PST) In-Reply-To: <65634d660911201612y12a9b5bnb6685da040ad832d@mail.gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: Tom Herbert wrote, On 11/21/2009 01:12 AM: >> I guess my confusion is from the: >> >> __raise_softirq_irqoff(NET_RX_SOFTIRQ); >> >> you are doing as you set the cpus in rps_remote_softirq_cpus. >> >> Why do you need to schedule the local RX softirq, when we know we're >> in a NAPI poll loop and thus that we're in a softirq, and thus that we >> will fire off the IPIs at the end of net_rx_action()? >> >> That's what you're doing, the softirq raising just seems superfluous. >> > > Ah, right. If RPS can't be used non-NAPI case, this line is now > superfluous. It can be removed. Hmm... mostly right. At least if it's wrt. my previous opinion. I meant only that non-NAPI case would be handled less optimally without this dedicated softirq, but __raise_softirq_irqoff(NET_RX_SOFTIRQ) or napi_schedule(&queue->backlog) could be called from netif_rx(). Jarek P.