Re: Fwd: [RFC PATCH net-next 0/3] virtio_net: add aRFS support

From: Tom Herbert <therbert@google.com>
To: Zhi Yong Wu <zwu.kernel@gmail.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Linux Netdev List <netdev@vger.kernel.org>,
	Eric Dumazet <edumazet@google.com>,
	"David S. Miller" <davem@davemloft.net>,
	Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Rusty Russell <rusty@rustcorp.com.au>,
	Jason Wang <jasowang@redhat.com>
Subject: Re: Fwd: [RFC PATCH net-next 0/3] virtio_net: add aRFS support
Date: Wed, 22 Jan 2014 10:00:37 -0800	[thread overview]
Message-ID: <CA+mtBx-Xv6xp3VCq=PKMyboAmDjUWzVrbUhr4WdKQRi1PCansg@mail.gmail.com> (raw)
In-Reply-To: <CAEH94LiqVpXUp3myHvTPVHaqrDpK2V6ii+w8Gip61PA+QF2apw@mail.gmail.com>

>> 1. The aRFS interface for the guest to specify which virtual queue to
>> receive a packet on is fairly straight forward.
>> 2. To hook into RFS, we need to match the virtual queue to the real
>> CPU it will processed on, and then program the RFS table for that flow
>> and CPU.
>> 3. NIC aRFS keys off the RFS tables so it can program the HW with the
>> correct queue for the CPU.
> Does anyone have time to make one conclusion for this discussion? in
> particular, how will rx packet be steered up the stack from guest
> virtio_net driver, virtio_net NIC, vhost_net, tun driver, host network
> stack, to physical NIC with more details?
> What is the role of each path units? otherwise this discussion wont
> get any meanful result, which is not what we expect.
>
Working code outweighs theoretical discussion :-). I think you started
on a good track with original patches, and I believe the tun path
should work pretty well (some performance numbers would still be good
to validate). Seems like there's enough hooks in the virtio_net path
to implement something meaningful and maybe get some numbers (maybe
ignore NIC aRFS in the first pass).

Tom

>>
>>> Stefan
>
>
>
> --
> Regards,
>
> Zhi Yong Wu