netdev - Re: Fwd: [RFC PATCH net-next 0/3] virtio

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Date:	Thu, 23 Jan 2014 16:23:57 +0200
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	Tom Herbert <therbert@...gle.com>
Cc:	Zhi Yong Wu <zwu.kernel@...il.com>,
	Ben Hutchings <bhutchings@...arflare.com>,
	Stefan Hajnoczi <stefanha@...hat.com>,
	Linux Netdev List <netdev@...r.kernel.org>,
	Eric Dumazet <edumazet@...gle.com>,
	"David S. Miller" <davem@...emloft.net>,
	Zhi Yong Wu <wuzhy@...ux.vnet.ibm.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Jason Wang <jasowang@...hat.com>
Subject: Re: Fwd: [RFC PATCH net-next 0/3] virtio_net: add aRFS support

On Wed, Jan 22, 2014 at 10:00:37AM -0800, Tom Herbert wrote:
> >> 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 :-).

So far all that was posted was an untested patchset.
Zhi Yong Wu did this intentionally to get early feedback, so
it's not surprising we got a theoretical discussion
as opposed to working code out of this.

> 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).

Yes, merging performance-oriented patches without any
performance numbers to show for it is strange.

> 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
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