Re: [RFC v2: Patch 1/3] net: hand off skb list to other cpu tosubmit to upper layer

From: Zhang, Yanmin
Date: Sun Mar 15 2009 - 23:21:36 EST


On Fri, 2009-03-13 at 10:06 -0700, Tom Herbert wrote:
> On Thu, Mar 12, 2009 at 11:43 PM, Zhang, Yanmin
> <yanmin_zhang@xxxxxxxxxxxxxxx> wrote:
> >
> > On Thu, 2009-03-12 at 14:08 +0000, Ben Hutchings wrote:
> > > On Thu, 2009-03-12 at 16:16 +0800, Zhang, Yanmin wrote:
> > > > On Wed, 2009-03-11 at 12:13 +0100, Andi Kleen wrote:

> > > Yes, that's exactly what they do. This feature is sometimes called
> > > Receive-Side Scaling (RSS) which is Microsoft's name for it. Microsoft
> > > requires Windows drivers performing RSS to provide the hash value to the
> > > networking stack, so Linux drivers for the same hardware should be able
> > > to do so too.
> > Oh, I didn't know the background. I need study more about network.
> > Thanks for explain it.
> >
>
> You'll definitely want to look at the hardware provided hash. We've
> been using a 10G NIC which provides a Toeplitz hash (the one defined
> by Microsoft) and a software RSS-like capability to move packets from
> an interrupting CPU to another for processing. The hash could be used
> to index to a set of CPUs, but we also use the hash as a connection
> identifier to key into a lookup table to steer packets to the CPU
> where the application is running based on the running CPU of the last
> recvmsg.
Your scenario is different from mine. My case is ip_forward which happens
in kernel and there is no application participating in the forwarding.

I might test the application communication on 10G NIC with my method later.


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