2 * Copyright (c) 2010-2011 Juniper Networks, Inc.
5 * This software was developed by Robert N. M. Watson under contract
6 * to Juniper Networks, Inc.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 #include <sys/cdefs.h>
32 __FBSDID("$FreeBSD$");
34 #include "opt_inet6.h"
35 #include "opt_pcbgroup.h"
38 #error "options RSS depends on options PCBGROUP"
41 #include <sys/param.h>
43 #include <sys/socket.h>
45 #include <sys/kernel.h>
47 #include <sys/sysctl.h>
50 #include <net/if_var.h>
51 #include <net/netisr.h>
53 #include <netinet/in.h>
54 #include <netinet/in_pcb.h>
55 #include <netinet/in_rss.h>
56 #include <netinet/in_var.h>
57 #include <netinet/toeplitz.h>
60 * Operating system parts of receiver-side scaling (RSS), which allows
61 * network cards to direct flows to particular receive queues based on hashes
62 * of header tuples. This implementation aligns RSS buckets with connection
63 * groups at the TCP/IP layer, so each bucket is associated with exactly one
64 * group. As a result, the group lookup structures (and lock) should have an
65 * effective affinity with exactly one CPU.
67 * Network device drivers needing to configure RSS will query this framework
68 * for parameters, such as the current RSS key, hashing policies, number of
69 * bits, and indirection table mapping hashes to buckets and CPUs. They may
70 * provide their own supplementary information, such as queue<->CPU bindings.
71 * It is the responsibility of the network device driver to inject packets
72 * into the stack on as close to the right CPU as possible, if playing by RSS
77 * - Synchronization for rss_key and other future-configurable parameters.
78 * - Event handler drivers can register to pick up RSS configuration changes.
79 * - Should we allow rss_basecpu to be configured?
80 * - Randomize key on boot.
82 * - Statistics on how often there's a misalignment between hardware
83 * placement and pcbgroup expectations.
86 SYSCTL_NODE(_net_inet, OID_AUTO, rss, CTLFLAG_RW, 0, "Receive-side steering");
89 * Toeplitz is the only required hash function in the RSS spec, so use it by
92 static u_int rss_hashalgo = RSS_HASH_TOEPLITZ;
93 SYSCTL_INT(_net_inet_rss, OID_AUTO, hashalgo, CTLFLAG_RD, &rss_hashalgo, 0,
94 "RSS hash algorithm");
95 TUNABLE_INT("net.inet.rss.hashalgo", &rss_hashalgo);
98 * Size of the indirection table; at most 128 entries per the RSS spec. We
99 * size it to at least 2 times the number of CPUs by default to allow useful
100 * rebalancing. If not set explicitly with a loader tunable, we tune based
101 * on the number of CPUs present.
103 * XXXRW: buckets might be better to use for the tunable than bits.
105 static u_int rss_bits;
106 SYSCTL_INT(_net_inet_rss, OID_AUTO, bits, CTLFLAG_RD, &rss_bits, 0,
108 TUNABLE_INT("net.inet.rss.bits", &rss_bits);
110 static u_int rss_mask;
111 SYSCTL_INT(_net_inet_rss, OID_AUTO, mask, CTLFLAG_RD, &rss_mask, 0,
114 static const u_int rss_maxbits = RSS_MAXBITS;
115 SYSCTL_INT(_net_inet_rss, OID_AUTO, maxbits, CTLFLAG_RD,
116 __DECONST(int *, &rss_maxbits), 0, "RSS maximum bits");
119 * RSS's own count of the number of CPUs it could be using for processing.
120 * Bounded to 64 by RSS constants.
122 static u_int rss_ncpus;
123 SYSCTL_INT(_net_inet_rss, OID_AUTO, ncpus, CTLFLAG_RD, &rss_ncpus, 0,
124 "Number of CPUs available to RSS");
126 #define RSS_MAXCPUS (1 << (RSS_MAXBITS - 1))
127 static const u_int rss_maxcpus = RSS_MAXCPUS;
128 SYSCTL_INT(_net_inet_rss, OID_AUTO, maxcpus, CTLFLAG_RD,
129 __DECONST(int *, &rss_maxcpus), 0, "RSS maximum CPUs that can be used");
132 * Variable exists just for reporting rss_bits in a user-friendly way.
134 static u_int rss_buckets;
135 SYSCTL_INT(_net_inet_rss, OID_AUTO, buckets, CTLFLAG_RD, &rss_buckets, 0,
139 * Base CPU number; devices will add this to all CPU numbers returned by the
140 * RSS indirection table. Currently unmodifable in FreeBSD.
142 static const u_int rss_basecpu;
143 SYSCTL_INT(_net_inet_rss, OID_AUTO, basecpu, CTLFLAG_RD,
144 __DECONST(int *, &rss_basecpu), 0, "RSS base CPU");
147 * RSS secret key, intended to prevent attacks on load-balancing. Its
148 * effectiveness may be limited by algorithm choice and available entropy
151 * XXXRW: And that we don't randomize it yet!
153 * XXXRW: This default is actually the default key from Chelsio T3 cards, as
154 * it offers reasonable distribution, unlike all-0 keys which always
155 * generate a hash of 0 (upsettingly).
157 static uint8_t rss_key[RSS_KEYSIZE] = {
158 0x43, 0xa3, 0x8f, 0xb0, 0x41, 0x67, 0x25, 0x3d,
159 0x25, 0x5b, 0x0e, 0xc2, 0x6d, 0x5a, 0x56, 0xda,
160 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
161 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
162 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
166 * RSS hash->CPU table, which maps hashed packet headers to particular CPUs.
167 * Drivers may supplement this table with a seperate CPU<->queue table when
168 * programming devices.
170 struct rss_table_entry {
171 uint8_t rte_cpu; /* CPU affinity of bucket. */
173 static struct rss_table_entry rss_table[RSS_TABLE_MAXLEN];
176 rss_init(__unused void *arg)
182 * Validate tunables, coerce to sensible values.
184 switch (rss_hashalgo) {
185 case RSS_HASH_TOEPLITZ:
190 printf("%s: invalid RSS hashalgo %u, coercing to %u",
191 __func__, rss_hashalgo, RSS_HASH_TOEPLITZ);
192 rss_hashalgo = RSS_HASH_TOEPLITZ;
196 * Count available CPUs.
198 * XXXRW: Note incorrect assumptions regarding contiguity of this set
202 for (i = 0; i <= mp_maxid; i++) {
207 if (rss_ncpus > RSS_MAXCPUS)
208 rss_ncpus = RSS_MAXCPUS;
211 * Tune RSS table entries to be no less than 2x the number of CPUs
212 * -- unless we're running uniprocessor, in which case there's not
213 * much point in having buckets to rearrange for load-balancing!
217 rss_bits = fls(rss_ncpus - 1) + 1;
220 * Microsoft limits RSS table entries to 128, so apply that
221 * limit to both auto-detected CPU counts and user-configured
224 if (rss_bits == 0 || rss_bits > RSS_MAXBITS) {
225 printf("%s: RSS bits %u not valid, coercing to %u",
226 __func__, rss_bits, RSS_MAXBITS);
227 rss_bits = RSS_MAXBITS;
231 * Figure out how many buckets to use; warn if less than the
232 * number of configured CPUs, although this is not a fatal
235 rss_buckets = (1 << rss_bits);
236 if (rss_buckets < rss_ncpus)
237 printf("%s: WARNING: rss_buckets (%u) less than "
238 "rss_ncpus (%u)\n", __func__, rss_buckets,
240 rss_mask = rss_buckets - 1;
248 * Set up initial CPU assignments: round-robin by default.
251 for (i = 0; i < rss_buckets; i++) {
252 rss_table[i].rte_cpu = cpuid;
253 cpuid = CPU_NEXT(cpuid);
259 * XXXRW: Not yet. If nothing else, will require an rss_isbadkey()
260 * loop to check for "bad" RSS keys.
263 SYSINIT(rss_init, SI_SUB_SOFTINTR, SI_ORDER_SECOND, rss_init, NULL);
266 rss_naive_hash(u_int keylen, const uint8_t *key, u_int datalen,
273 for (i = 0; i < keylen; i++)
275 for (i = 0; i < datalen; i++)
281 rss_hash(u_int datalen, const uint8_t *data)
284 switch (rss_hashalgo) {
285 case RSS_HASH_TOEPLITZ:
286 return (toeplitz_hash(sizeof(rss_key), rss_key, datalen,
290 return (rss_naive_hash(sizeof(rss_key), rss_key, datalen,
294 panic("%s: unsupported/unknown hashalgo %d", __func__,
300 * Hash an IPv4 2-tuple.
303 rss_hash_ip4_2tuple(struct in_addr src, struct in_addr dst)
305 uint8_t data[sizeof(src) + sizeof(dst)];
309 bcopy(&src, &data[datalen], sizeof(src));
310 datalen += sizeof(src);
311 bcopy(&dst, &data[datalen], sizeof(dst));
312 datalen += sizeof(dst);
313 return (rss_hash(datalen, data));
317 * Hash an IPv4 4-tuple.
320 rss_hash_ip4_4tuple(struct in_addr src, u_short srcport, struct in_addr dst,
323 uint8_t data[sizeof(src) + sizeof(dst) + sizeof(srcport) +
328 bcopy(&src, &data[datalen], sizeof(src));
329 datalen += sizeof(src);
330 bcopy(&dst, &data[datalen], sizeof(dst));
331 datalen += sizeof(dst);
332 bcopy(&srcport, &data[datalen], sizeof(srcport));
333 datalen += sizeof(srcport);
334 bcopy(&dstport, &data[datalen], sizeof(dstport));
335 datalen += sizeof(dstport);
336 return (rss_hash(datalen, data));
341 * Hash an IPv6 2-tuple.
344 rss_hash_ip6_2tuple(struct in6_addr src, struct in6_addr dst)
346 uint8_t data[sizeof(src) + sizeof(dst)];
350 bcopy(&src, &data[datalen], sizeof(src));
351 datalen += sizeof(src);
352 bcopy(&dst, &data[datalen], sizeof(dst));
353 datalen += sizeof(dst);
354 return (rss_hash(datalen, data));
358 * Hash an IPv6 4-tuple.
361 rss_hash_ip6_4tuple(struct in6_addr src, u_short srcport,
362 struct in6_addr dst, u_short dstport)
364 uint8_t data[sizeof(src) + sizeof(dst) + sizeof(srcport) +
369 bcopy(&src, &data[datalen], sizeof(src));
370 datalen += sizeof(src);
371 bcopy(&dst, &data[datalen], sizeof(dst));
372 datalen += sizeof(dst);
373 bcopy(&srcport, &data[datalen], sizeof(srcport));
374 datalen += sizeof(srcport);
375 bcopy(&dstport, &data[datalen], sizeof(dstport));
376 datalen += sizeof(dstport);
377 return (rss_hash(datalen, data));
382 * Query the number of RSS bits in use.
392 * Query the RSS bucket associated with an RSS hash.
395 rss_getbucket(u_int hash)
398 return (hash & rss_mask);
402 * Query the RSS CPU associated with an RSS bucket.
405 rss_getcpu(u_int bucket)
408 return (rss_table[bucket].rte_cpu);
412 * netisr CPU affinity lookup given just the hash and hashtype.
415 rss_hash2cpuid(uint32_t hash_val, uint32_t hash_type)
419 case M_HASHTYPE_RSS_IPV4:
420 case M_HASHTYPE_RSS_TCP_IPV4:
421 return (rss_getcpu(rss_getbucket(hash_val)));
423 return (NETISR_CPUID_NONE);
428 * netisr CPU affinity lookup routine for use by protocols.
431 rss_m2cpuid(struct mbuf *m, uintptr_t source, u_int *cpuid)
435 *cpuid = rss_hash2cpuid(m->m_pkthdr.flowid, M_HASHTYPE_GET(m));
440 * Query the RSS hash algorithm.
443 rss_gethashalgo(void)
446 return (rss_hashalgo);
450 * Query the current RSS key; likely to be used by device drivers when
451 * configuring hardware RSS. Caller must pass an array of size RSS_KEYSIZE.
453 * XXXRW: Perhaps we should do the accept-a-length-and-truncate thing?
456 rss_getkey(uint8_t *key)
459 bcopy(rss_key, key, sizeof(rss_key));
463 * Query the number of buckets; this may be used by both network device
464 * drivers, which will need to populate hardware shadows of the software
465 * indirection table, and the network stack itself (such as when deciding how
466 * many connection groups to allocate).
469 rss_getnumbuckets(void)
472 return (rss_buckets);
476 * Query the number of CPUs in use by RSS; may be useful to device drivers
477 * trying to figure out how to map a larger number of CPUs into a smaller
478 * number of receive queues.
488 * XXXRW: Confirm that sysctl -a won't dump this keying material, don't want
489 * it appearing in debugging output unnecessarily.
492 sysctl_rss_key(SYSCTL_HANDLER_ARGS)
494 uint8_t temp_rss_key[RSS_KEYSIZE];
497 error = priv_check(req->td, PRIV_NETINET_HASHKEY);
501 bcopy(rss_key, temp_rss_key, sizeof(temp_rss_key));
502 error = sysctl_handle_opaque(oidp, temp_rss_key,
503 sizeof(temp_rss_key), req);
506 if (req->newptr != NULL) {
507 /* XXXRW: Not yet. */
512 SYSCTL_PROC(_net_inet_rss, OID_AUTO, key,
513 CTLTYPE_OPAQUE | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, sysctl_rss_key,
514 "", "RSS keying material");