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Date: Sun, 14 Aug 2011 02:05:25 -0400 (EDT) From: Jason Wang <jasowang@...hat.com> To: Eric Dumazet <eric.dumazet@...il.com> Cc: mst@...hat.com, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, virtualization@...ts.linux-foundation.org, davem@...emloft.net, krkumar2@...ibm.com, rusty@...tcorp.com.au, qemu-devel@...gnu.org, kvm@...r.kernel.org, mirq-linux@...e.qmqm.pl Subject: Re: [net-next RFC PATCH 4/7] tuntap: multiqueue support ----- 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@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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