Re: [Qemu-devel] [PATCH 10/12] virtio-net: multiqueue support

[Wanlong Gao <gaowanlong@cn.fujitsu.com>]

On 01/08/2013 06:14 PM, Jason Wang wrote:
> On 01/08/2013 06:00 PM, Wanlong Gao wrote:
>> On 01/08/2013 05:51 PM, Jason Wang wrote:
>>> On 01/08/2013 05:49 PM, Wanlong Gao wrote:
>>>> On 01/08/2013 05:29 PM, Jason Wang wrote:
>>>>> On 01/08/2013 05:07 PM, Wanlong Gao wrote:
>>>>>> On 12/28/2012 06:32 PM, Jason Wang wrote:
>>>>>>> +    } else if (nc->peer->info->type !=  NET_CLIENT_OPTIONS_KIND_TAP) {
>>>>>>> +        ret = -1;
>>>>>>> +    } else {
>>>>>>> +        ret = tap_detach(nc->peer);
>>>>>>> +    }
>>>>>>> +
>>>>>>> +    return ret;
>>>>>>> +}
>>>>>>> +
>>>>>>> +static void virtio_net_set_queues(VirtIONet *n)
>>>>>>> +{
>>>>>>> +    int i;
>>>>>>> +
>>>>>>> +    for (i = 0; i < n->max_queues; i++) {
>>>>>>> +        if (i < n->curr_queues) {
>>>>>>> +            assert(!peer_attach(n, i));
>>>>>>> +        } else {
>>>>>>> +            assert(!peer_detach(n, i));
>>>>>> I got a assert here,
>>>>>> qemu-system-x86_64: /work/git/qemu/hw/virtio-net.c:330: virtio_net_set_queues: Assertion `!peer_detach(n, i)' failed.
>>>>>>
>>>>>> Any thoughts?
>>>>>>
>>>>>> Thanks,
>>>>>> Wanlong Gao
>>>>> Thanks for the testing, which steps or cases did you met this assertion,
>>>>> migration, reboot or just changing the number of virtqueues?
>>>> I use the 3.8-rc2 to test it again, I saw this tag has the multi-tap support.
>>>>
>>>> I just can't start the QEMU use  -netdev tap,id=hostnet0,queues=2,fd=%d,fd=%d -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:ce:7b:29,bus=pci.0,addr=0x3
>>>>
>>>> I pre-opened two tap fds, did I missing something?
>>> Nothing missed :) It should work.
>>>
>>> Could you please try not use fd=X and let qemu to create the file
>>> descriptors by itself? Btw, how did you create the two tap fds?
>> Can it create descriptors itself? I get 
>> qemu-system-x86_64: -netdev tap,id=hostnet0,queues=2: Device 'tap' could not be initialized
> 
> You need prepare an ifup script which default at /etc/qemu-ifup (like
> following). Or you may try to add a script=no after:
> 
> #!/bin/sh
> 
> switch=kvmbr0
> 
> /sbin/ifconfig $1 0.0.0.0 up
> /usr/sbin/brctl addif $switch $1
> /usr/sbin/brctl stp $switch off
> 
> This will let qemu create a tap fd itself and make it to be connected to
> a port of the bridge caled kvmbr0.
>>
>> I create the tap fd like this, and dup create the second fd, third fd, right?
> 
> The second and third fd should be created with TUNSETIFF with the same
> tap_name also. Btw, you need to specify a IFF_MULTI_QUEUE flag to tell
> the kernel you want to create a multiqueue tap device, otherwise the
> second and third calling of TUNSETIFF will fail.

Thank you for teaching me, I'll try it tomorrow.

Regards,
Wanlong Gao

> 
> Thanks
>>
>> 	int tap_fd = open("/dev/net/tun", O_RDWR);
>> 	int vhost_fd = open("/dev/vhost-net", O_RDWR);
>> 	char *tap_name = "tap";
>> 	char cmd[2048];
>> 	char brctl[256];
>> 	char netup[256];
>> 	struct ifreq ifr;
>> 	if (tap_fd < 0) {
>> 		printf("open tun device failed\n");
>> 		return -1;
>> 	}
>> 	if (vhost_fd < 0) {
>> 		printf("open vhost-net device failed\n");
>> 		return -1;
>> 	}
>> 	memset(&ifr, 0, sizeof(ifr));
>> 	memcpy(ifr.ifr_name, tap_name, sizeof(tap_name));
>> 	ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
>>
>> 	/*
>> 	 * setup tap net device
>> 	 */
>> 	if (ioctl(tap_fd, TUNSETIFF, &ifr) < 0) {
>> 		printf("setup tap net device failed\n");
>> 		return -1;
>> 	}
>>
>> 	sprintf(brctl, "brctl addif virbr0 %s", tap_name);
>> 	sprintf(netup, "ifconfig %s up", tap_name);
>> 	system(brctl);
>> 	system(netup);
>>
>> Thanks,
>> Wanlong Gao
>>
>>
>>> Thanks
>>>> Thanks,
>>>> Wanlong Gao
>>>>
>>>>>>> +        }
>>>>>>> +    }
>>>>>>> +}
>>>>>>> +
>>>>>>> +static void virtio_net_set_multiqueue(VirtIONet *n, int multiqueue, int ctrl);
>>>>>>> +
>>>>>> --
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>>>
> 
>