svn commit: r222702 - head/sys/sys

[Julian Elischer]

On 6/4/11 4:31 PM, Robert Watson wrote:
> Author: rwatson
> Date: Sat Jun  4 23:31:41 2011
> New Revision: 222702
> URL: http://svn.freebsd.org/changeset/base/222702
>
> Log:
>    Allocate four bits from the mbuf flags field to represent the hash
>    type of a software- or hardware-generated hash held in the
>    mbuf.m_pkthdr.flowid field, and provide accessor macros to easily
>    clear, set, receive, and test for hash values.  Some of these
>    constants correspond to RSS hash types, but we don't want to limit
>    ourselves to that, as a number of other hashing techniques are in
>    use on hardware supported by FreeBSD.
>
>    Mark the M_FLOWID flag as deprecated; I hope to remove this before
>    9.0, changing drivers and the stack over to using the new
>    M_HASHTYPEBITS, most likely to use M_HASHTYPE_OPAQUE as we don't yet
>    want to nail down the KPI for RSS key/bucket management for device
>    drivers.
>
>    MFC after:      3 days
>    Reviewed by:    bz
>    Sponsored by:   Juniper Networks, Inc.
>
> Modified:
>    head/sys/sys/mbuf.h
>
> Modified: head/sys/sys/mbuf.h
> ==============================================================================
> --- head/sys/sys/mbuf.h	Sat Jun  4 23:31:33 2011	(r222701)
> +++ head/sys/sys/mbuf.h	Sat Jun  4 23:31:41 2011	(r222702)
> @@ -199,7 +199,9 @@ struct mbuf {
>   #define	M_PROTO6	0x00080000 /* protocol-specific */
>   #define	M_PROTO7	0x00100000 /* protocol-specific */
>   #define	M_PROTO8	0x00200000 /* protocol-specific */
> -#define	M_FLOWID	0x00400000 /* flowid is valid */
> +#define	M_FLOWID	0x00400000 /* deprecated: flowid is valid */
> +#define	M_HASHTYPEBITS	0x0F000000 /* mask of bits holding flowid hash type */
> +
>   /*
>    * For RELENG_{6,7} steal these flags for limited multiple routing table
>    * support. In RELENG_8 and beyond, use just one flag and a tag.
> @@ -215,11 +217,45 @@ struct mbuf {
>       (M_PROTO1|M_PROTO2|M_PROTO3|M_PROTO4|M_PROTO5|M_PROTO6|M_PROTO7|M_PROTO8)
>
>   /*
> + * Network interface cards are able to hash protocol fields (such as IPv4
> + * addresses and TCP port numbers) classify packets into flows.  These flows
> + * can then be used to maintain ordering while delivering packets to the OS
> + * via parallel input queues, as well as to provide a stateless affinity
> + * model.  NIC drivers can pass up the hash via m->m_pkthdr.flowid, and set
> + * m_flag fields to indicate how the hash should be interpreted by the
> + * network stack.
> + *
> + * Most NICs support RSS, which provides ordering and explicit affinity, and
> + * use the hash m_flag bits to indicate what header fields were covered by
> + * the hash.  M_HASHTYPE_OPAQUE can be set by non-RSS cards or configurations
> + * that provide an opaque flow identifier, allowing for ordering and
> + * distribution without explicit affinity.
> + */
> +#define	M_HASHTYPE_SHIFT		24
> +#define	M_HASHTYPE_NONE			0x0
> +#define	M_HASHTYPE_RSS_IPV4		0x1	/* IPv4 2-tuple */
> +#define	M_HASHTYPE_RSS_TCP_IPV4		0x2	/* TCPv4 4-tuple */
> +#define	M_HASHTYPE_RSS_IPV6		0x3	/* IPv6 2-tuple */
> +#define	M_HASHTYPE_RSS_TCP_IPV6		0x4	/* TCPv6 4-tuple */
> +#define	M_HASHTYPE_RSS_IPV6_EX		0x5	/* IPv6 2-tuple + ext hdrs */
> +#define	M_HASHTYPE_RSS_TCP_IPV6_EX	0x6	/* TCPv6 4-tiple + ext hdrs */
> +#define	M_HASHTYPE_OPAQUE		0xf	/* ordering, not affinity */
> +
> +#define	M_HASHTYPE_CLEAR(m)	(m)->m_flags&= ~(M_HASHTYPEBITS)
> +#define	M_HASHTYPE_GET(m)	(((m)->m_flags&  M_HASHTYPEBITS)>>  \
> +				    M_HASHTYPE_SHIFT)
> +#define	M_HASHTYPE_SET(m, v)	do {					\
> +	(m)->m_flags&= ~M_HASHTYPEBITS;				\
> +	(m)->m_flags |= ((v)<<  M_HASHTYPE_SHIFT);			\
> +while (0)
> +#define	M_HASHTYPE_TEST(m, v)	(M_HASHTYPE_GET(m) == (v))
> +
> +/*
>    * Flags preserved when copying m_pkthdr.
>    */
>   #define	M_COPYFLAGS \
>       (M_PKTHDR|M_EOR|M_RDONLY|M_PROTOFLAGS|M_SKIP_FIREWALL|M_BCAST|M_MCAST|\
> -     M_FRAG|M_FIRSTFRAG|M_LASTFRAG|M_VLANTAG|M_PROMISC|M_FIB)
> +     M_FRAG|M_FIRSTFRAG|M_LASTFRAG|M_VLANTAG|M_PROMISC|M_FIB|M_HASHTYPEBITS)
>
>   /*
>    * External buffer types: identify ext_buf type.
>
>
hmm note that my stealing of 4 bits for FIB was supposed to go away 
for 8 and beyond.
We need to do an mbuf redesign.. at this stage, I guess it's a project 
for 10.