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Commit 8de4b2f3 authored by Wanlong Gao's avatar Wanlong Gao Committed by David S. Miller
Browse files

virtio-net: reset virtqueue affinity when doing cpu hotplug 



Add a cpu notifier to virtio-net, so that we can reset the
virtqueue affinity if the cpu hotplug happens. It improve
the performance through enabling or disabling the virtqueue
affinity after doing cpu hotplug.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Eric Dumazet <erdnetdev@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: virtualization@lists.linux-foundation.org
Cc: netdev@vger.kernel.org
Signed-off-by: default avatarWanlong Gao <gaowanlong@cn.fujitsu.com>
Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8898c21c

drivers/net/virtio_net.c

+33 −0
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#include <linux/scatterlist.h>

#include <linux/if_vlan.h>

#include <linux/slab.h>

#include <linux/cpu.h>



static int napi_weight = 128;

module_param(napi_weight, int, 0444);
@@ -126,6 +127,9 @@ struct virtnet_info { 


	/* Per-cpu variable to show the mapping from CPU to virtqueue */

	int __percpu *vq_index;



	/* CPU hot plug notifier */

	struct notifier_block nb;

};



struct skb_vnet_hdr {
@@ -1067,6 +1071,26 @@ static void virtnet_set_affinity(struct virtnet_info *vi) 
	vi->affinity_hint_set = true;

}



static int virtnet_cpu_callback(struct notifier_block *nfb,

			        unsigned long action, void *hcpu)

{

	struct virtnet_info *vi = container_of(nfb, struct virtnet_info, nb);



	switch(action & ~CPU_TASKS_FROZEN) {

	case CPU_ONLINE:

	case CPU_DOWN_FAILED:

	case CPU_DEAD:

		virtnet_set_affinity(vi);

		break;

	case CPU_DOWN_PREPARE:

		virtnet_clean_affinity(vi, (long)hcpu);

		break;

	default:

		break;

	}

	return NOTIFY_OK;

}



static void virtnet_get_ringparam(struct net_device *dev,

				struct ethtool_ringparam *ring)

{
@@ -1541,6 +1565,13 @@ static int virtnet_probe(struct virtio_device *vdev) 
		}

	}



	vi->nb.notifier_call = &virtnet_cpu_callback;

	err = register_hotcpu_notifier(&vi->nb);

	if (err) {

		pr_debug("virtio_net: registering cpu notifier failed\n");

		goto free_recv_bufs;

	}



	/* Assume link up if device can't report link status,

	   otherwise get link status from config. */

	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) {
@@ -1587,6 +1618,8 @@ static void virtnet_remove(struct virtio_device *vdev) 
{

	struct virtnet_info *vi = vdev->priv;



	unregister_hotcpu_notifier(&vi->nb);



	/* Prevent config work handler from accessing the device. */

	mutex_lock(&vi->config_lock);

	vi->config_enable = false;