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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: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Wanlong Gao 2013-01-24 23:51:31 +00:00 committed by David S. Miller
parent 8898c21cf3
commit 8de4b2f3ae
1 changed files with 33 additions and 0 deletions
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33
drivers/net/virtio_net.c
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@ -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;