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>
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 2f6fe9b..35c00c5 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -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 @@
/* 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 @@
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 @@
}
}
+ 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 @@
{
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;
