Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753902Ab3I0OdV (ORCPT ); Fri, 27 Sep 2013 10:33:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39875 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753725Ab3I0OdR (ORCPT ); Fri, 27 Sep 2013 10:33:17 -0400 Date: Fri, 27 Sep 2013 17:35:29 +0300 From: "Michael S. Tsirkin" To: Jason Wang Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Rusty Russell Subject: Re: [PATCH net-next] virtio-net: switch to use XPS to choose txq Message-ID: <20130927143529.GA30007@redhat.com> References: <1380261444-40918-1-git-send-email-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1380261444-40918-1-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5324 Lines: 171 On Fri, Sep 27, 2013 at 01:57:24PM +0800, Jason Wang wrote: > We used to use a percpu structure vq_index to record the cpu to queue > mapping, this is suboptimal since it duplicates the work of XPS and > loses all other XPS functionality such as allowing use to configure > their own transmission steering strategy. > > So this patch switches to use XPS and suggest a default mapping when > the number of cpus is equal to the number of queues. With XPS support, > there's no need for keeping per-cpu vq_index and .ndo_select_queue(), > so they were removed also. > > Cc: Rusty Russell > Cc: Michael S. Tsirkin > Signed-off-by: Jason Wang More lines deleted that added is good :) But how does the result perform? About the same? > --- > drivers/net/virtio_net.c | 55 +++++++-------------------------------------- > 1 files changed, 9 insertions(+), 46 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index defec2b..4102c1b 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -127,9 +127,6 @@ struct virtnet_info { > /* Does the affinity hint is set for virtqueues? */ > bool affinity_hint_set; > > - /* Per-cpu variable to show the mapping from CPU to virtqueue */ > - int __percpu *vq_index; > - > /* CPU hot plug notifier */ > struct notifier_block nb; > }; > @@ -1063,7 +1060,6 @@ static int virtnet_vlan_rx_kill_vid(struct net_device *dev, > static void virtnet_clean_affinity(struct virtnet_info *vi, long hcpu) > { > int i; > - int cpu; > > if (vi->affinity_hint_set) { > for (i = 0; i < vi->max_queue_pairs; i++) { > @@ -1073,20 +1069,11 @@ static void virtnet_clean_affinity(struct virtnet_info *vi, long hcpu) > > vi->affinity_hint_set = false; > } > - > - i = 0; > - for_each_online_cpu(cpu) { > - if (cpu == hcpu) { > - *per_cpu_ptr(vi->vq_index, cpu) = -1; > - } else { > - *per_cpu_ptr(vi->vq_index, cpu) = > - ++i % vi->curr_queue_pairs; > - } > - } > } > > static void virtnet_set_affinity(struct virtnet_info *vi) > { > + cpumask_var_t cpumask; > int i; > int cpu; > > @@ -1100,15 +1087,21 @@ static void virtnet_set_affinity(struct virtnet_info *vi) > return; > } > > + if (!alloc_cpumask_var(&cpumask, GFP_KERNEL)) > + return; > + > i = 0; > for_each_online_cpu(cpu) { > virtqueue_set_affinity(vi->rq[i].vq, cpu); > virtqueue_set_affinity(vi->sq[i].vq, cpu); > - *per_cpu_ptr(vi->vq_index, cpu) = i; > + cpumask_clear(cpumask); > + cpumask_set_cpu(cpu, cpumask); > + netif_set_xps_queue(vi->dev, cpumask, i); > i++; > } > > vi->affinity_hint_set = true; > + free_cpumask_var(cpumask); > } > > static int virtnet_cpu_callback(struct notifier_block *nfb, > @@ -1217,28 +1210,6 @@ static int virtnet_change_mtu(struct net_device *dev, int new_mtu) > return 0; > } > > -/* To avoid contending a lock hold by a vcpu who would exit to host, select the > - * txq based on the processor id. > - */ > -static u16 virtnet_select_queue(struct net_device *dev, struct sk_buff *skb) > -{ > - int txq; > - struct virtnet_info *vi = netdev_priv(dev); > - > - if (skb_rx_queue_recorded(skb)) { > - txq = skb_get_rx_queue(skb); > - } else { > - txq = *__this_cpu_ptr(vi->vq_index); > - if (txq == -1) > - txq = 0; > - } > - > - while (unlikely(txq >= dev->real_num_tx_queues)) > - txq -= dev->real_num_tx_queues; > - > - return txq; > -} > - > static const struct net_device_ops virtnet_netdev = { > .ndo_open = virtnet_open, > .ndo_stop = virtnet_close, > @@ -1250,7 +1221,6 @@ static const struct net_device_ops virtnet_netdev = { > .ndo_get_stats64 = virtnet_stats, > .ndo_vlan_rx_add_vid = virtnet_vlan_rx_add_vid, > .ndo_vlan_rx_kill_vid = virtnet_vlan_rx_kill_vid, > - .ndo_select_queue = virtnet_select_queue, > #ifdef CONFIG_NET_POLL_CONTROLLER > .ndo_poll_controller = virtnet_netpoll, > #endif > @@ -1559,10 +1529,6 @@ static int virtnet_probe(struct virtio_device *vdev) > if (vi->stats == NULL) > goto free; > > - vi->vq_index = alloc_percpu(int); > - if (vi->vq_index == NULL) > - goto free_stats; > - > mutex_init(&vi->config_lock); > vi->config_enable = true; > INIT_WORK(&vi->config_work, virtnet_config_changed_work); > @@ -1589,7 +1555,7 @@ static int virtnet_probe(struct virtio_device *vdev) > /* Allocate/initialize the rx/tx queues, and invoke find_vqs */ > err = init_vqs(vi); > if (err) > - goto free_index; > + goto free_stats; > > netif_set_real_num_tx_queues(dev, 1); > netif_set_real_num_rx_queues(dev, 1); > @@ -1640,8 +1606,6 @@ free_recv_bufs: > free_vqs: > cancel_delayed_work_sync(&vi->refill); > virtnet_del_vqs(vi); > -free_index: > - free_percpu(vi->vq_index); > free_stats: > free_percpu(vi->stats); > free: > @@ -1678,7 +1642,6 @@ static void virtnet_remove(struct virtio_device *vdev) > > flush_work(&vi->config_work); > > - free_percpu(vi->vq_index); > free_percpu(vi->stats); > free_netdev(vi->dev); > } > -- > 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/