[rfc] tcp timer update for RSS

[Adrian Chadd]

.. and i've done a little more than no testing, so far so good.

http://people.freebsd.org/~adrian/norse/20140514-tcp-rss-timers-2.diff

This adds IP_FLOWID, IP_FLOWTYPE and IP_RSSCPUID to fetch the socket
flowid, flowtype and cpuid from the inp. It's mostly for debugging for
now.

Thanks,



-a


On 14 May 2014 21:43, Adrian Chadd <adrian at freebsd.org> wrote:
> Hi,
>
> here's a completely untested patch for discussion. I'm emailing it out
> mostly as a "is this a good idea" patch rather than a "it should just
> be committed" patch.
>
> The RSS stuff from Robert maps connections to pcbgroups based on the
> RSS hash, but it doesn't map the TCP timers the same way. So by
> default they're all on swi0 and the per CPU timers don't take the hash
> type or correctly choose the CPU.
>
> This patch:
>
> http://people.freebsd.org/~adrian/norse/20140514-tcp-rss-timers-1.diff
>
> does a few things:
>
> * it stores the hashtype in the inp as well as the flowid;
> * the rss code grows a new method that maps the flowid/hashtype to a cpuid
> * .. and the existing mbuf to cpuid method now uses this;
> * the tcp timer code now has an inline function that knows about RSS
> and defaults to the existing way of doing things if RSS isn't enabled.
>
> There's still a bunch of work left before all the lock contention
> compartmentalization and balancing of RSS is realised. I'm just
> chewing off the little corner bits that are easy to get done now.
>
> So, any comments? I'll give it a proper whirl on some 10G hardware in
> a few days but I thought I'd at least get the general idea out there
> for comment.
>
> Thanks,
>
>
>
>
> -a