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Message-ID: <50DACF22.5090707@cn.fujitsu.com> Date: Wed, 26 Dec 2012 18:19:14 +0800 From: Wanlong Gao <gaowanlong@...fujitsu.com> To: Jason Wang <jasowang@...hat.com> CC: linux-kernel@...r.kernel.org, Rusty Russell <rusty@...tcorp.com.au>, "Michael S. Tsirkin" <mst@...hat.com>, virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org Subject: Re: [RFC PATCH] virtio-net: reset virtqueue affinity when doing cpu hotplug On 12/26/2012 06:06 PM, Jason Wang wrote: > On 12/26/2012 03:06 PM, Wanlong Gao wrote: >> 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. > > Hi Wanlong: > > Thanks for looking at this. >> Cc: Rusty Russell <rusty@...tcorp.com.au> >> Cc: "Michael S. Tsirkin" <mst@...hat.com> >> Cc: Jason Wang <jasowang@...hat.com> >> Cc: virtualization@...ts.linux-foundation.org >> Cc: netdev@...r.kernel.org >> Signed-off-by: Wanlong Gao <gaowanlong@...fujitsu.com> >> --- >> drivers/net/virtio_net.c | 39 ++++++++++++++++++++++++++++++++++++++- >> 1 file changed, 38 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c >> index a6fcf15..9710cf4 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); >> @@ -34,6 +35,8 @@ static bool csum = true, gso = true; >> module_param(csum, bool, 0444); >> module_param(gso, bool, 0444); >> >> +static bool cpu_hotplug = false; >> + >> /* FIXME: MTU in config. */ >> #define MAX_PACKET_LEN (ETH_HLEN + VLAN_HLEN + ETH_DATA_LEN) >> #define GOOD_COPY_LEN 128 >> @@ -1041,6 +1044,26 @@ static void virtnet_set_affinity(struct virtnet_info *vi, bool set) >> vi->affinity_hint_set = false; >> } >> >> +static int virtnet_cpu_callback(struct notifier_block *nfb, >> + unsigned long action, void *hcpu) >> +{ >> + switch(action) { >> + case CPU_ONLINE: >> + case CPU_ONLINE_FROZEN: >> + case CPU_DEAD: >> + case CPU_DEAD_FROZEN: >> + cpu_hotplug = true; >> + break; >> + default: >> + break; >> + } >> + return NOTIFY_OK; >> +} >> + >> +static struct notifier_block virtnet_cpu_notifier = { >> + .notifier_call = virtnet_cpu_callback, >> +}; >> + >> static void virtnet_get_ringparam(struct net_device *dev, >> struct ethtool_ringparam *ring) >> { >> @@ -1131,7 +1154,14 @@ static int virtnet_change_mtu(struct net_device *dev, int new_mtu) >> */ >> static u16 virtnet_select_queue(struct net_device *dev, struct sk_buff *skb) >> { >> - int txq = skb_rx_queue_recorded(skb) ? skb_get_rx_queue(skb) : >> + int txq; >> + >> + if (unlikely(cpu_hotplug == true)) { >> + virtnet_set_affinity(netdev_priv(dev), true); >> + cpu_hotplug = false; >> + } >> + > > Why don't you just do this in callback? Callback can just give us a "hcpu", can't get the virtnet_info from callback. Am I missing something? > > btw. Does qemu/kvm support cpu-hotplug now? >From http://www.linux-kvm.org/page/CPUHotPlug, I saw that qemu-kvm can support hotplug but failed to merge to qemu.git, right? Thanks, Wanlong Gao -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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