[Qemu-devel] wiki: update missing info on "Enabling multi-queue" section of vhost-user

[Qemu-devel] wiki: update missing info on "Enabling multi-queue" section of vhost-user

[Lin Ma]

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Hi Marcel,
 
I found that the information on "Enabling multi-queue" in http://wiki.qemu.org/Features/vhost-user-ovs-dpdk
are inaccurate.
 
In ovs 2.5 or older, The option 'other_config:n-dpdk-rxqs' is used and there is no options:n_rxq.
The n_rxq is available since post 2.5.0.
 
But when setup an interface's option using ovs-vsctl, It doesn't check whether the option is valid or not.
So if a user follows the instruction of above wiki page to setup the vhost-user multi queues in ovs 2.5-,
The user wont get any error information but the vms which have vhost-user multi queues nics dont work and the user
gets confused.
 
I think that we should mentioned on wiki:
In ovs 2.5 or older version: The usage is:
......
ovs-vsctl set Open_vSwitch . other_config:n-dpdk-rxqs=<queues_nr, the same as QEMU>
//BTW: It only supports setting up same number of rx queues for all of PMD netdevs.
......
 
 
In post ovs 2.5, The usage is:
......
ovs-vsctl set Interface vhost-user1 options:n_rxq=<queues_nr, the same as QEMU>
ovs-vsctl set Interface vhost-user2 options:n_rxq=<queues_nr, the same as QEMU>
......
 
 
Moreover, For vhost-user live migration support, Because qemu needs vhost-user backend providing
VHOST_USER_PROTOCOL_F_LOG_SHMFD feature bit since commit 1be0ac2.
The dpdk commit d639996 provides this feature bit but it isn't available in dpdk 2.2.0, It may be merged into 2.3.0.
In this case, If a user uses qemu 2.5+dpdk 2.2+ovs, The vhost-user live migration wont succeed.
 
Should it be mentioned on wiki as well? I dont have permissions to update wiki pages, So sending the information to list.
 
 
Lin

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Re: [Qemu-devel] wiki: update missing info on "Enabling multi-queue" section of vhost-user

[Marcel Apfelbaum]

On 03/21/2016 12:10 PM, Lin Ma wrote:
> Hi Marcel,
> I found that the information on "Enabling multi-queue" in http://wiki.qemu.org/Features/vhost-user-ovs-dpdk
> are inaccurate.
> In ovs 2.5 or older, The option 'other_config:n-dpdk-rxqs' is used and there is no options:n_rxq.
> The n_rxq is available since post 2.5.0.
> But when setup an interface's option using ovs-vsctl, It doesn't check whether the option is valid or not.
> So if a user follows the instruction of above wiki page to setup the vhost-user multi queues in ovs 2.5-,
> The user wont get any error information but the vms which have vhost-user multi queues nics dont work and the user
> gets confused.
> I think that we should mentioned on wiki:
> In ovs 2.5 or older version: The usage is:
> ......
> ovs-vsctl set Open_vSwitch . other_config:n-dpdk-rxqs=<queues_nr, the same as QEMU>
> //BTW: It only supports setting up same number of rx queues for all of PMD netdevs.
> ......
> In post ovs 2.5, The usage is:
> ......
> ovs-vsctl set Interface vhost-user1 options:n_rxq=<queues_nr, the same as QEMU>
> ovs-vsctl set Interface vhost-user2 options:n_rxq=<queues_nr, the same as QEMU>
> ......
> Moreover, For vhost-user live migration support, Because qemu needs vhost-user backend providing
> VHOST_USER_PROTOCOL_F_LOG_SHMFD feature bit since commit 1be0ac2.
> The dpdk commit d639996 provides this feature bit but it isn't available in dpdk 2.2.0, It may be merged into 2.3.0.
> In this case, If a user uses qemu 2.5+dpdk 2.2+ovs, The vhost-user live migration wont succeed.
> Should it be mentioned on wiki as well? I dont have permissions to update wiki pages, So sending the information to list.
> Lin

Hi Lin,

Thank you for the important update, would you want update the wiki yourself?
If you have the time, please reply me on a private thread with the desired username
and I'll supply a temporary password.

Thanks,
Marcel