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.
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