From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Herbert Subject: Re: [PATCH v7] rps: Receive Packet Steering Date: Fri, 12 Mar 2010 15:08:12 -0800 Message-ID: <65634d661003121508m3d348973k63a6ae9ca1f12f9f@mail.gmail.com> References: <1268429319.2947.10.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: davem@davemloft.net, netdev@vger.kernel.org To: Eric Dumazet Return-path: Received: from smtp-out.google.com ([216.239.44.51]:6467 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933282Ab0CLXIP (ORCPT ); Fri, 12 Mar 2010 18:08:15 -0500 Received: from kpbe18.cbf.corp.google.com (kpbe18.cbf.corp.google.com [172.25.105.82]) by smtp-out.google.com with ESMTP id o2CN8EFx017983 for ; Fri, 12 Mar 2010 15:08:14 -0800 Received: from fg-out-1718.google.com (fgae21.prod.google.com [10.86.56.21]) by kpbe18.cbf.corp.google.com with ESMTP id o2CN8CsG022303 for ; Fri, 12 Mar 2010 15:08:13 -0800 Received: by fg-out-1718.google.com with SMTP id e21so556753fga.0 for ; Fri, 12 Mar 2010 15:08:12 -0800 (PST) In-Reply-To: <1268429319.2947.10.camel@edumazet-laptop> Sender: netdev-owner@vger.kernel.org List-ID: > One last point about placement of rxhash in struct sk_buff, that I > missed in my previous review, sorry... > > You put it right before cb[48] which is now aligned to 8 bytes (since > commit da3f5cf1 skbuff: align sk_buff::cb to 64 bit and close some > potential holes), so this adds a 4 bytes hole. > > Please put it elsewhere, possibly close to fields that are read in > get_rps_cpu() (skb->queue_mapping, skb->protocol, skb->data, ...) to > minimize number of cache lines that dispatcher cpu has to bring into its > cache, before giving skb to another cpu for IP/TCP processing. > Looks like it will fit right before queue_mapping, I'll put it there. Tom