Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754087Ab3I2DPC (ORCPT ); Sat, 28 Sep 2013 23:15:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:63102 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753466Ab3I2DO6 (ORCPT ); Sat, 28 Sep 2013 23:14:58 -0400 Message-ID: <52479B28.9080609@redhat.com> Date: Sun, 29 Sep 2013 11:14:48 +0800 From: Jason Wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.0 MIME-Version: 1.0 To: "Michael S. Tsirkin" 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 References: <1380261444-40918-1-git-send-email-jasowang@redhat.com> <20130927143529.GA30007@redhat.com> In-Reply-To: <20130927143529.GA30007@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5556 Lines: 174 On 09/27/2013 10:35 PM, Michael S. Tsirkin wrote: > 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? > Yes, 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/