[rfc] tcp timer update for RSS

[Adrian Chadd]

Ok, I've given this a whirl on a slightly larger system. There's no
10Gbit/sec in it yet, but it's stable under 64,000 sockets at
1Gbit/sec.

I'm going to commit this over the next couple of days unless there are
any objections. The defaults are still the same so it won't affect the
rest of you.

-a


On 14 May 2014 22:26, Adrian Chadd <adrian at freebsd.org> wrote:
> .. 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