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
31 #include "opt_inet6.h"
33 #include <sys/param.h>
35 #include <sys/socket.h>
37 #include <sys/kernel.h>
39 #include <sys/sysctl.h>
43 #include <net/if_var.h>
44 #include <net/netisr.h>
45 #include <net/rss_config.h>
46 #include <net/toeplitz.h>
49 * Operating system parts of receiver-side scaling (RSS), which allows
50 * network cards to direct flows to particular receive queues based on hashes
51 * of header tuples. This implementation aligns RSS buckets with connection
52 * groups at the TCP/IP layer, so each bucket is associated with exactly one
53 * group. As a result, the group lookup structures (and lock) should have an
54 * effective affinity with exactly one CPU.
56 * Network device drivers needing to configure RSS will query this framework
57 * for parameters, such as the current RSS key, hashing policies, number of
58 * bits, and indirection table mapping hashes to buckets and CPUs. They may
59 * provide their own supplementary information, such as queue<->CPU bindings.
60 * It is the responsibility of the network device driver to inject packets
61 * into the stack on as close to the right CPU as possible, if playing by RSS
66 * - Synchronization for rss_key and other future-configurable parameters.
67 * - Event handler drivers can register to pick up RSS configuration changes.
68 * - Should we allow rss_basecpu to be configured?
69 * - Randomize key on boot.
71 * - Statistics on how often there's a misalignment between hardware
72 * placement and pcbgroup expectations.
75 SYSCTL_DECL(_net_inet);
76 SYSCTL_NODE(_net_inet, OID_AUTO, rss, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
77 "Receive-side steering");
80 * Toeplitz is the only required hash function in the RSS spec, so use it by
83 static u_int rss_hashalgo = RSS_HASH_TOEPLITZ;
84 SYSCTL_INT(_net_inet_rss, OID_AUTO, hashalgo, CTLFLAG_RDTUN, &rss_hashalgo, 0,
85 "RSS hash algorithm");
88 * Size of the indirection table; at most 128 entries per the RSS spec. We
89 * size it to at least 2 times the number of CPUs by default to allow useful
90 * rebalancing. If not set explicitly with a loader tunable, we tune based
91 * on the number of CPUs present.
93 * XXXRW: buckets might be better to use for the tunable than bits.
95 static u_int rss_bits;
96 SYSCTL_INT(_net_inet_rss, OID_AUTO, bits, CTLFLAG_RDTUN, &rss_bits, 0,
99 static u_int rss_mask;
100 SYSCTL_INT(_net_inet_rss, OID_AUTO, mask, CTLFLAG_RD, &rss_mask, 0,
103 static const u_int rss_maxbits = RSS_MAXBITS;
104 SYSCTL_INT(_net_inet_rss, OID_AUTO, maxbits, CTLFLAG_RD,
105 __DECONST(int *, &rss_maxbits), 0, "RSS maximum bits");
108 * RSS's own count of the number of CPUs it could be using for processing.
109 * Bounded to 64 by RSS constants.
111 static u_int rss_ncpus;
112 SYSCTL_INT(_net_inet_rss, OID_AUTO, ncpus, CTLFLAG_RD, &rss_ncpus, 0,
113 "Number of CPUs available to RSS");
115 #define RSS_MAXCPUS (1 << (RSS_MAXBITS - 1))
116 static const u_int rss_maxcpus = RSS_MAXCPUS;
117 SYSCTL_INT(_net_inet_rss, OID_AUTO, maxcpus, CTLFLAG_RD,
118 __DECONST(int *, &rss_maxcpus), 0, "RSS maximum CPUs that can be used");
121 * Variable exists just for reporting rss_bits in a user-friendly way.
123 static u_int rss_buckets;
124 SYSCTL_INT(_net_inet_rss, OID_AUTO, buckets, CTLFLAG_RD, &rss_buckets, 0,
128 * Base CPU number; devices will add this to all CPU numbers returned by the
129 * RSS indirection table. Currently unmodifable in FreeBSD.
131 static const u_int rss_basecpu;
132 SYSCTL_INT(_net_inet_rss, OID_AUTO, basecpu, CTLFLAG_RD,
133 __DECONST(int *, &rss_basecpu), 0, "RSS base CPU");
136 * Print verbose debugging messages.
141 SYSCTL_INT(_net_inet_rss, OID_AUTO, debug, CTLFLAG_RWTUN, &rss_debug, 0,
145 * RSS secret key, intended to prevent attacks on load-balancing. Its
146 * effectiveness may be limited by algorithm choice and available entropy
149 * XXXRW: And that we don't randomize it yet!
151 * This is the default Microsoft RSS specification key which is also
152 * the Chelsio T5 firmware default key.
154 static uint8_t rss_key[RSS_KEYSIZE] = {
155 0x6d, 0x5a, 0x56, 0xda, 0x25, 0x5b, 0x0e, 0xc2,
156 0x41, 0x67, 0x25, 0x3d, 0x43, 0xa3, 0x8f, 0xb0,
157 0xd0, 0xca, 0x2b, 0xcb, 0xae, 0x7b, 0x30, 0xb4,
158 0x77, 0xcb, 0x2d, 0xa3, 0x80, 0x30, 0xf2, 0x0c,
159 0x6a, 0x42, 0xb7, 0x3b, 0xbe, 0xac, 0x01, 0xfa,
163 * RSS hash->CPU table, which maps hashed packet headers to particular CPUs.
164 * Drivers may supplement this table with a separate CPU<->queue table when
165 * programming devices.
167 struct rss_table_entry {
168 uint8_t rte_cpu; /* CPU affinity of bucket. */
170 static struct rss_table_entry rss_table[RSS_TABLE_MAXLEN];
173 rss_init(__unused void *arg)
179 * Validate tunables, coerce to sensible values.
181 switch (rss_hashalgo) {
182 case RSS_HASH_TOEPLITZ:
187 RSS_DEBUG("invalid RSS hashalgo %u, coercing to %u\n",
188 rss_hashalgo, RSS_HASH_TOEPLITZ);
189 rss_hashalgo = RSS_HASH_TOEPLITZ;
193 * Count available CPUs.
195 * XXXRW: Note incorrect assumptions regarding contiguity of this set
199 for (i = 0; i <= mp_maxid; i++) {
204 if (rss_ncpus > RSS_MAXCPUS)
205 rss_ncpus = RSS_MAXCPUS;
208 * Tune RSS table entries to be no less than 2x the number of CPUs
209 * -- unless we're running uniprocessor, in which case there's not
210 * much point in having buckets to rearrange for load-balancing!
214 rss_bits = fls(rss_ncpus - 1) + 1;
217 * Microsoft limits RSS table entries to 128, so apply that
218 * limit to both auto-detected CPU counts and user-configured
221 if (rss_bits == 0 || rss_bits > RSS_MAXBITS) {
222 RSS_DEBUG("RSS bits %u not valid, coercing to %u\n",
223 rss_bits, RSS_MAXBITS);
224 rss_bits = RSS_MAXBITS;
228 * Figure out how many buckets to use; warn if less than the
229 * number of configured CPUs, although this is not a fatal
232 rss_buckets = (1 << rss_bits);
233 if (rss_buckets < rss_ncpus)
234 RSS_DEBUG("WARNING: rss_buckets (%u) less than "
235 "rss_ncpus (%u)\n", rss_buckets, rss_ncpus);
236 rss_mask = rss_buckets - 1;
244 * Set up initial CPU assignments: round-robin by default.
247 for (i = 0; i < rss_buckets; i++) {
248 rss_table[i].rte_cpu = cpuid;
249 cpuid = CPU_NEXT(cpuid);
255 * XXXRW: Not yet. If nothing else, will require an rss_isbadkey()
256 * loop to check for "bad" RSS keys.
259 SYSINIT(rss_init, SI_SUB_SOFTINTR, SI_ORDER_SECOND, rss_init, NULL);
262 rss_naive_hash(u_int keylen, const uint8_t *key, u_int datalen,
269 for (i = 0; i < keylen; i++)
271 for (i = 0; i < datalen; i++)
277 rss_hash(u_int datalen, const uint8_t *data)
280 switch (rss_hashalgo) {
281 case RSS_HASH_TOEPLITZ:
282 return (toeplitz_hash(sizeof(rss_key), rss_key, datalen,
286 return (rss_naive_hash(sizeof(rss_key), rss_key, datalen,
290 panic("%s: unsupported/unknown hashalgo %d", __func__,
296 * Query the number of RSS bits in use.
306 * Query the RSS bucket associated with an RSS hash.
309 rss_getbucket(u_int hash)
312 return (hash & rss_mask);
316 * Query the RSS layer bucket associated with the given
317 * entry in the RSS hash space.
319 * The RSS indirection table is 0 .. rss_buckets-1,
320 * covering the low 'rss_bits' of the total 128 slot
321 * RSS indirection table. So just mask off rss_bits and
324 * NIC drivers can then iterate over the 128 slot RSS
325 * indirection table and fetch which RSS bucket to
326 * map it to. This will typically be a CPU queue
329 rss_get_indirection_to_bucket(u_int index)
332 return (index & rss_mask);
336 * Query the RSS CPU associated with an RSS bucket.
339 rss_getcpu(u_int bucket)
342 return (rss_table[bucket].rte_cpu);
346 * netisr CPU affinity lookup given just the hash and hashtype.
349 rss_hash2cpuid(uint32_t hash_val, uint32_t hash_type)
353 case M_HASHTYPE_RSS_IPV4:
354 case M_HASHTYPE_RSS_TCP_IPV4:
355 case M_HASHTYPE_RSS_UDP_IPV4:
356 case M_HASHTYPE_RSS_IPV6:
357 case M_HASHTYPE_RSS_TCP_IPV6:
358 case M_HASHTYPE_RSS_UDP_IPV6:
359 return (rss_getcpu(rss_getbucket(hash_val)));
361 return (NETISR_CPUID_NONE);
366 * Query the RSS bucket associated with the given hash value and
370 rss_hash2bucket(uint32_t hash_val, uint32_t hash_type, uint32_t *bucket_id)
374 case M_HASHTYPE_RSS_IPV4:
375 case M_HASHTYPE_RSS_TCP_IPV4:
376 case M_HASHTYPE_RSS_UDP_IPV4:
377 case M_HASHTYPE_RSS_IPV6:
378 case M_HASHTYPE_RSS_TCP_IPV6:
379 case M_HASHTYPE_RSS_UDP_IPV6:
380 *bucket_id = rss_getbucket(hash_val);
388 * netisr CPU affinity lookup routine for use by protocols.
391 rss_m2cpuid(struct mbuf *m, uintptr_t source, u_int *cpuid)
395 *cpuid = rss_hash2cpuid(m->m_pkthdr.flowid, M_HASHTYPE_GET(m));
400 rss_m2bucket(struct mbuf *m, uint32_t *bucket_id)
405 return(rss_hash2bucket(m->m_pkthdr.flowid, M_HASHTYPE_GET(m),
410 * Query the RSS hash algorithm.
413 rss_gethashalgo(void)
416 return (rss_hashalgo);
420 * Query the current RSS key; likely to be used by device drivers when
421 * configuring hardware RSS. Caller must pass an array of size RSS_KEYSIZE.
423 * XXXRW: Perhaps we should do the accept-a-length-and-truncate thing?
426 rss_getkey(uint8_t *key)
429 bcopy(rss_key, key, sizeof(rss_key));
433 * Query the number of buckets; this may be used by both network device
434 * drivers, which will need to populate hardware shadows of the software
435 * indirection table, and the network stack itself (such as when deciding how
436 * many connection groups to allocate).
439 rss_getnumbuckets(void)
442 return (rss_buckets);
446 * Query the number of CPUs in use by RSS; may be useful to device drivers
447 * trying to figure out how to map a larger number of CPUs into a smaller
448 * number of receive queues.
458 * Return the supported RSS hash configuration.
460 * NICs should query this to determine what to configure in their redirection
464 rss_gethashconfig(void)
467 /* Return 4-tuple for TCP; 2-tuple for others */
469 * UDP may fragment more often than TCP and thus we'll end up with
470 * NICs returning 2-tuple fragments.
471 * udp_init() and udplite_init() both currently initialise things
473 * So for now disable UDP 4-tuple hashing until all of the other
474 * pieces are in place.
477 RSS_HASHTYPE_RSS_IPV4
478 | RSS_HASHTYPE_RSS_TCP_IPV4
479 | RSS_HASHTYPE_RSS_IPV6
480 | RSS_HASHTYPE_RSS_TCP_IPV6
481 | RSS_HASHTYPE_RSS_IPV6_EX
482 | RSS_HASHTYPE_RSS_TCP_IPV6_EX
484 | RSS_HASHTYPE_RSS_UDP_IPV4
485 | RSS_HASHTYPE_RSS_UDP_IPV6
486 | RSS_HASHTYPE_RSS_UDP_IPV6_EX
492 * XXXRW: Confirm that sysctl -a won't dump this keying material, don't want
493 * it appearing in debugging output unnecessarily.
496 sysctl_rss_key(SYSCTL_HANDLER_ARGS)
498 uint8_t temp_rss_key[RSS_KEYSIZE];
501 error = priv_check(req->td, PRIV_NETINET_HASHKEY);
505 bcopy(rss_key, temp_rss_key, sizeof(temp_rss_key));
506 error = sysctl_handle_opaque(oidp, temp_rss_key,
507 sizeof(temp_rss_key), req);
510 if (req->newptr != NULL) {
511 /* XXXRW: Not yet. */
516 SYSCTL_PROC(_net_inet_rss, OID_AUTO, key,
517 CTLTYPE_OPAQUE | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, sysctl_rss_key,
518 "", "RSS keying material");
521 sysctl_rss_bucket_mapping(SYSCTL_HANDLER_ARGS)
528 error = sysctl_wire_old_buffer(req, 0);
531 sb = sbuf_new_for_sysctl(NULL, NULL, 512, req);
534 for (i = 0; i < rss_buckets; i++) {
535 sbuf_printf(sb, "%s%d:%d", i == 0 ? "" : " ",
539 error = sbuf_finish(sb);
544 SYSCTL_PROC(_net_inet_rss, OID_AUTO, bucket_mapping,
545 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
546 sysctl_rss_bucket_mapping, "", "RSS bucket -> CPU mapping");