From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752062Ab1HNGFi (ORCPT ); Sun, 14 Aug 2011 02:05:38 -0400 Received: from mx3-phx2.redhat.com ([209.132.183.24]:47140 "EHLO mx3-phx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751003Ab1HNGFg convert rfc822-to-8bit (ORCPT ); Sun, 14 Aug 2011 02:05:36 -0400 Date: Sun, 14 Aug 2011 02:05:25 -0400 (EDT) From: Jason Wang To: Eric Dumazet Cc: mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, davem@davemloft.net, krkumar2@in.ibm.com, rusty@rustcorp.com.au, qemu-devel@nongnu.org, kvm@vger.kernel.org, mirq-linux@rere.qmqm.pl Message-ID: <1465655104.165911.1313301925197.JavaMail.root@zmail05.collab.prod.int.phx2.redhat.com> In-Reply-To: <1313159376.2354.26.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> Subject: Re: [net-next RFC PATCH 4/7] tuntap: multiqueue support MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT X-Originating-IP: [10.5.5.71] X-Mailer: Zimbra 6.0.9_GA_2686 (ZimbraWebClient - FF3.0 (Linux)/6.0.9_GA_2686) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- Original Message ----- > Le vendredi 12 août 2011 à 09:55 +0800, Jason Wang a écrit : > > >+ rxq = skb_get_rxhash(skb); > >+ if (rxq) { > >+ tfile = rcu_dereference(tun->tfiles[rxq % numqueues]); > >+ if (tfile) > >+ goto out; > >+ } > > You can avoid an expensive divide with following trick : > > u32 idx = ((u64)rxq * numqueues) >> 32; > Sure. > > > > -static struct tun_struct *tun_get(struct file *file) > > +static void tun_detach_all(struct net_device *dev) > > { > > - return __tun_get(file->private_data); > > + struct tun_struct *tun = netdev_priv(dev); > > + struct tun_file *tfile, *tfile_list[MAX_TAP_QUEUES]; > > + int i, j = 0; > > + > > + spin_lock(&tun_lock); > > + > > + for (i = 0; i < MAX_TAP_QUEUES && tun->numqueues; i++) { > > + tfile = rcu_dereference_protected(tun->tfiles[i], > > + lockdep_is_held(&tun_lock)); > > + if (tfile) { > > + wake_up_all(&tfile->wq.wait); > > + tfile_list[i++] = tfile; > > typo here, you want tfile_list[j++] = tfile; > Yes, thanks for catching this. > > + rcu_assign_pointer(tun->tfiles[i], NULL); > > + rcu_assign_pointer(tfile->tun, NULL); > > + --tun->numqueues; > > + } > > + } > > + BUG_ON(tun->numqueues != 0); > > + spin_unlock(&tun_lock); > > + > > + synchronize_rcu(); > > + for(--j; j >= 0; j--) > > + sock_put(&tfile_list[j]->sk); > > } > > > > Could you take a look at net/packet/af_packet.c, to check how David > did > the whole fanout thing ? > > __fanout_unlink() > > Trick is to not leave NULL entries in the tun->tfiles[] array. > > It makes things easier in hot path. Sure I would go to take a look at this. > > > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html