svn commit: r218371 - head/sys/netinet

[Robert Watson]

On Sun, 6 Feb 2011, Randall Stewart wrote:

> Author: rrs
> Date: Sun Feb  6 13:17:40 2011
> New Revision: 218371
> URL: http://svn.freebsd.org/changeset/base/218371
>
> Log:
>  1) Use same scheme Michael and I discussed for a selected for a flowid
>  2) If flowid is not set, arrange so it is stored.
>  3) If flowid is set by lower layer, use it.

Beware that selecting a flowid at this level has implications not just for 
load balancing, but also CPU affinity in the transmit path for multiqueue 
drivers such as cxgb, etc.

With the pcbgroup patch going into the tree soon, flowids will grow types to 
be set by device drivers, network layers, etc, so that other layers can use 
those semantics.  Once we do that, we'll need to retain that at the connection 
level, etc, as we..

Robert

>
>  MFC after:	3 Months
>
> Modified:
>  head/sys/netinet/sctp_input.c
>
> Modified: head/sys/netinet/sctp_input.c
> ==============================================================================
> --- head/sys/netinet/sctp_input.c	Sun Feb  6 12:21:29 2011	(r218370)
> +++ head/sys/netinet/sctp_input.c	Sun Feb  6 13:17:40 2011	(r218371)
> @@ -5946,32 +5946,32 @@ sctp_input(struct mbuf *m, int off)
> 	struct sctphdr *sh;
> 	int offset;
> 	int cpu_to_use;
> -	uint32_t tag;
> +	uint32_t flowid, tag;
>
> 	if (mp_ncpus > 1) {
> -		ip = mtod(m, struct ip *);
> -		offset = off + sizeof(*sh);
> -		if (SCTP_BUF_LEN(m) < offset) {
> -			if ((m = m_pullup(m, offset)) == 0) {
> -				SCTP_STAT_INCR(sctps_hdrops);
> -				return;
> -			}
> -			ip = mtod(m, struct ip *);
> -		}
> -		sh = (struct sctphdr *)((caddr_t)ip + off);
> -		if (sh->v_tag) {
> -			tag = htonl(sh->v_tag);
> +		if (m->m_flags & M_FLOWID) {
> +			flowid = m->m_pkthdr.flowid;
> 		} else {
> 			/*
> -			 * Distribute new INIT's to all CPU's don't just
> -			 * pick on 0.
> +			 * No flow id built by lower layers fix it so we
> +			 * create one.
> 			 */
> -			struct timeval tv;
> -
> -			(void)SCTP_GETTIME_TIMEVAL(&tv);
> -			tag = (uint32_t) tv.tv_usec;
> +			ip = mtod(m, struct ip *);
> +			offset = off + sizeof(*sh);
> +			if (SCTP_BUF_LEN(m) < offset) {
> +				if ((m = m_pullup(m, offset)) == 0) {
> +					SCTP_STAT_INCR(sctps_hdrops);
> +					return;
> +				}
> +				ip = mtod(m, struct ip *);
> +			}
> +			sh = (struct sctphdr *)((caddr_t)ip + off);
> +			tag = htonl(sh->v_tag);
> +			flowid = tag ^ ntohs(sh->dest_port) ^ ntohs(sh->src_port);
> +			m->m_pkthdr.flowid = flowid;
> +			m->m_flags |= M_FLOWID;
> 		}
> -		cpu_to_use = sctp_cpuarry[tag % mp_ncpus];
> +		cpu_to_use = sctp_cpuarry[flowid % mp_ncpus];
> 		sctp_queue_to_mcore(m, off, cpu_to_use);
> 		return;
> 	}
>