From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH v2] Receive Packet Steering Date: Wed, 10 Jun 2009 01:23:42 -0700 (PDT) Message-ID: <20090610.012342.121254416.davem@davemloft.net> References: <65634d660905032103h614225dbg9911e290f5537fbf@mail.gmail.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: therbert@google.com Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:44578 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754559AbZFJIXk (ORCPT ); Wed, 10 Jun 2009 04:23:40 -0400 In-Reply-To: <65634d660905032103h614225dbg9911e290f5537fbf@mail.gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Tom Herbert Date: Sun, 3 May 2009 21:03:01 -0700 > This is an update of the receive packet steering patch (RPS) based on received > comments (thanks for all the comments). Improvements are: > > 1) Removed config option for the feature. > 2) Made scheduling of backlog NAPI devices between CPUs lockless and much > simpler. > 3) Added new softirq to do defer sending IPIs for coalescing. > 4) Imported hash from simple_rx_hash. Eliminates modulo operation to convert > hash to index. > 5) If no cpu is found for packet steering, then netif_receive_skb processes > packet inline as before without queueing. In paritcular if RPS is not > configured on a device the receive path is unchanged from current for > NAPI devices (one additional conditional). > > Signed-off-by: Tom Herbert Just to keep this topic alive, I want to mention two things: 1) Just the other day support for the IXGBE "Flow Director" was added to net-next-2.6, it basically does flow steering in hardware. It remembers where the last TX for a flow was made, and steers RX traffic there. It's essentially a HW implementation of what we're proposing here to do in software. 2) I'm steadily still trying to get struct sk_buff to the point where we can replace the list handling implementation with a standard "struct list_head" and thus union that with a "struct call_single_data" so we can use remote cpu soft-irqs for software packet flow steering.