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"
36 #include <sys/param.h>
38 #include <sys/socket.h>
40 #include <sys/kernel.h>
42 #include <sys/sysctl.h>
46 #include <net/if_var.h>
47 #include <net/netisr.h>
48 #include <net/rss_config.h>
49 #include <net/toeplitz.h>
52 * Operating system parts of receiver-side scaling (RSS), which allows
53 * network cards to direct flows to particular receive queues based on hashes
54 * of header tuples. This implementation aligns RSS buckets with connection
55 * groups at the TCP/IP layer, so each bucket is associated with exactly one
56 * group. As a result, the group lookup structures (and lock) should have an
57 * effective affinity with exactly one CPU.
59 * Network device drivers needing to configure RSS will query this framework
60 * for parameters, such as the current RSS key, hashing policies, number of
61 * bits, and indirection table mapping hashes to buckets and CPUs. They may
62 * provide their own supplementary information, such as queue<->CPU bindings.
63 * It is the responsibility of the network device driver to inject packets
64 * into the stack on as close to the right CPU as possible, if playing by RSS
69 * - Synchronization for rss_key and other future-configurable parameters.
70 * - Event handler drivers can register to pick up RSS configuration changes.
71 * - Should we allow rss_basecpu to be configured?
72 * - Randomize key on boot.
74 * - Statistics on how often there's a misalignment between hardware
75 * placement and pcbgroup expectations.
78 SYSCTL_DECL(_net_inet);
79 SYSCTL_NODE(_net_inet, OID_AUTO, rss, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
80 "Receive-side steering");
83 * Toeplitz is the only required hash function in the RSS spec, so use it by
86 static u_int rss_hashalgo = RSS_HASH_TOEPLITZ;
87 SYSCTL_INT(_net_inet_rss, OID_AUTO, hashalgo, CTLFLAG_RDTUN, &rss_hashalgo, 0,
88 "RSS hash algorithm");
91 * Size of the indirection table; at most 128 entries per the RSS spec. We
92 * size it to at least 2 times the number of CPUs by default to allow useful
93 * rebalancing. If not set explicitly with a loader tunable, we tune based
94 * on the number of CPUs present.
96 * XXXRW: buckets might be better to use for the tunable than bits.
98 static u_int rss_bits;
99 SYSCTL_INT(_net_inet_rss, OID_AUTO, bits, CTLFLAG_RDTUN, &rss_bits, 0,
102 static u_int rss_mask;
103 SYSCTL_INT(_net_inet_rss, OID_AUTO, mask, CTLFLAG_RD, &rss_mask, 0,
106 static const u_int rss_maxbits = RSS_MAXBITS;
107 SYSCTL_INT(_net_inet_rss, OID_AUTO, maxbits, CTLFLAG_RD,
108 __DECONST(int *, &rss_maxbits), 0, "RSS maximum bits");
111 * RSS's own count of the number of CPUs it could be using for processing.
112 * Bounded to 64 by RSS constants.
114 static u_int rss_ncpus;
115 SYSCTL_INT(_net_inet_rss, OID_AUTO, ncpus, CTLFLAG_RD, &rss_ncpus, 0,
116 "Number of CPUs available to RSS");
118 #define RSS_MAXCPUS (1 << (RSS_MAXBITS - 1))
119 static const u_int rss_maxcpus = RSS_MAXCPUS;
120 SYSCTL_INT(_net_inet_rss, OID_AUTO, maxcpus, CTLFLAG_RD,
121 __DECONST(int *, &rss_maxcpus), 0, "RSS maximum CPUs that can be used");
124 * Variable exists just for reporting rss_bits in a user-friendly way.
126 static u_int rss_buckets;
127 SYSCTL_INT(_net_inet_rss, OID_AUTO, buckets, CTLFLAG_RD, &rss_buckets, 0,
131 * Base CPU number; devices will add this to all CPU numbers returned by the
132 * RSS indirection table. Currently unmodifable in FreeBSD.
134 static const u_int rss_basecpu;
135 SYSCTL_INT(_net_inet_rss, OID_AUTO, basecpu, CTLFLAG_RD,
136 __DECONST(int *, &rss_basecpu), 0, "RSS base CPU");
139 * Print verbose debugging messages.
144 SYSCTL_INT(_net_inet_rss, OID_AUTO, debug, CTLFLAG_RWTUN, &rss_debug, 0,
148 * RSS secret key, intended to prevent attacks on load-balancing. Its
149 * effectiveness may be limited by algorithm choice and available entropy
152 * XXXRW: And that we don't randomize it yet!
154 * This is the default Microsoft RSS specification key which is also
155 * the Chelsio T5 firmware default key.
157 static uint8_t rss_key[RSS_KEYSIZE] = {
158 0x6d, 0x5a, 0x56, 0xda, 0x25, 0x5b, 0x0e, 0xc2,
159 0x41, 0x67, 0x25, 0x3d, 0x43, 0xa3, 0x8f, 0xb0,
160 0xd0, 0xca, 0x2b, 0xcb, 0xae, 0x7b, 0x30, 0xb4,
161 0x77, 0xcb, 0x2d, 0xa3, 0x80, 0x30, 0xf2, 0x0c,
162 0x6a, 0x42, 0xb7, 0x3b, 0xbe, 0xac, 0x01, 0xfa,
166 * RSS hash->CPU table, which maps hashed packet headers to particular CPUs.
167 * Drivers may supplement this table with a separate 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 RSS_DEBUG("invalid RSS hashalgo %u, coercing to %u\n",
191 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 RSS_DEBUG("RSS bits %u not valid, coercing to %u\n",
226 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 RSS_DEBUG("WARNING: rss_buckets (%u) less than "
238 "rss_ncpus (%u)\n", rss_buckets, rss_ncpus);
239 rss_mask = rss_buckets - 1;
247 * Set up initial CPU assignments: round-robin by default.
250 for (i = 0; i < rss_buckets; i++) {
251 rss_table[i].rte_cpu = cpuid;
252 cpuid = CPU_NEXT(cpuid);
258 * XXXRW: Not yet. If nothing else, will require an rss_isbadkey()
259 * loop to check for "bad" RSS keys.
262 SYSINIT(rss_init, SI_SUB_SOFTINTR, SI_ORDER_SECOND, rss_init, NULL);
265 rss_naive_hash(u_int keylen, const uint8_t *key, u_int datalen,
272 for (i = 0; i < keylen; i++)
274 for (i = 0; i < datalen; i++)
280 rss_hash(u_int datalen, const uint8_t *data)
283 switch (rss_hashalgo) {
284 case RSS_HASH_TOEPLITZ:
285 return (toeplitz_hash(sizeof(rss_key), rss_key, datalen,
289 return (rss_naive_hash(sizeof(rss_key), rss_key, datalen,
293 panic("%s: unsupported/unknown hashalgo %d", __func__,
299 * Query the number of RSS bits in use.
309 * Query the RSS bucket associated with an RSS hash.
312 rss_getbucket(u_int hash)
315 return (hash & rss_mask);
319 * Query the RSS layer bucket associated with the given
320 * entry in the RSS hash space.
322 * The RSS indirection table is 0 .. rss_buckets-1,
323 * covering the low 'rss_bits' of the total 128 slot
324 * RSS indirection table. So just mask off rss_bits and
327 * NIC drivers can then iterate over the 128 slot RSS
328 * indirection table and fetch which RSS bucket to
329 * map it to. This will typically be a CPU queue
332 rss_get_indirection_to_bucket(u_int index)
335 return (index & rss_mask);
339 * Query the RSS CPU associated with an RSS bucket.
342 rss_getcpu(u_int bucket)
345 return (rss_table[bucket].rte_cpu);
349 * netisr CPU affinity lookup given just the hash and hashtype.
352 rss_hash2cpuid(uint32_t hash_val, uint32_t hash_type)
356 case M_HASHTYPE_RSS_IPV4:
357 case M_HASHTYPE_RSS_TCP_IPV4:
358 case M_HASHTYPE_RSS_UDP_IPV4:
359 case M_HASHTYPE_RSS_IPV6:
360 case M_HASHTYPE_RSS_TCP_IPV6:
361 case M_HASHTYPE_RSS_UDP_IPV6:
362 return (rss_getcpu(rss_getbucket(hash_val)));
364 return (NETISR_CPUID_NONE);
369 * Query the RSS bucket associated with the given hash value and
373 rss_hash2bucket(uint32_t hash_val, uint32_t hash_type, uint32_t *bucket_id)
377 case M_HASHTYPE_RSS_IPV4:
378 case M_HASHTYPE_RSS_TCP_IPV4:
379 case M_HASHTYPE_RSS_UDP_IPV4:
380 case M_HASHTYPE_RSS_IPV6:
381 case M_HASHTYPE_RSS_TCP_IPV6:
382 case M_HASHTYPE_RSS_UDP_IPV6:
383 *bucket_id = rss_getbucket(hash_val);
391 * netisr CPU affinity lookup routine for use by protocols.
394 rss_m2cpuid(struct mbuf *m, uintptr_t source, u_int *cpuid)
398 *cpuid = rss_hash2cpuid(m->m_pkthdr.flowid, M_HASHTYPE_GET(m));
403 rss_m2bucket(struct mbuf *m, uint32_t *bucket_id)
408 return(rss_hash2bucket(m->m_pkthdr.flowid, M_HASHTYPE_GET(m),
413 * Query the RSS hash algorithm.
416 rss_gethashalgo(void)
419 return (rss_hashalgo);
423 * Query the current RSS key; likely to be used by device drivers when
424 * configuring hardware RSS. Caller must pass an array of size RSS_KEYSIZE.
426 * XXXRW: Perhaps we should do the accept-a-length-and-truncate thing?
429 rss_getkey(uint8_t *key)
432 bcopy(rss_key, key, sizeof(rss_key));
436 * Query the number of buckets; this may be used by both network device
437 * drivers, which will need to populate hardware shadows of the software
438 * indirection table, and the network stack itself (such as when deciding how
439 * many connection groups to allocate).
442 rss_getnumbuckets(void)
445 return (rss_buckets);
449 * Query the number of CPUs in use by RSS; may be useful to device drivers
450 * trying to figure out how to map a larger number of CPUs into a smaller
451 * number of receive queues.
461 * Return the supported RSS hash configuration.
463 * NICs should query this to determine what to configure in their redirection
467 rss_gethashconfig(void)
470 /* Return 4-tuple for TCP; 2-tuple for others */
472 * UDP may fragment more often than TCP and thus we'll end up with
473 * NICs returning 2-tuple fragments.
474 * udp_init() and udplite_init() both currently initialise things
476 * So for now disable UDP 4-tuple hashing until all of the other
477 * pieces are in place.
480 RSS_HASHTYPE_RSS_IPV4
481 | RSS_HASHTYPE_RSS_TCP_IPV4
482 | RSS_HASHTYPE_RSS_IPV6
483 | RSS_HASHTYPE_RSS_TCP_IPV6
484 | RSS_HASHTYPE_RSS_IPV6_EX
485 | RSS_HASHTYPE_RSS_TCP_IPV6_EX
487 | RSS_HASHTYPE_RSS_UDP_IPV4
488 | RSS_HASHTYPE_RSS_UDP_IPV6
489 | RSS_HASHTYPE_RSS_UDP_IPV6_EX
495 * XXXRW: Confirm that sysctl -a won't dump this keying material, don't want
496 * it appearing in debugging output unnecessarily.
499 sysctl_rss_key(SYSCTL_HANDLER_ARGS)
501 uint8_t temp_rss_key[RSS_KEYSIZE];
504 error = priv_check(req->td, PRIV_NETINET_HASHKEY);
508 bcopy(rss_key, temp_rss_key, sizeof(temp_rss_key));
509 error = sysctl_handle_opaque(oidp, temp_rss_key,
510 sizeof(temp_rss_key), req);
513 if (req->newptr != NULL) {
514 /* XXXRW: Not yet. */
519 SYSCTL_PROC(_net_inet_rss, OID_AUTO, key,
520 CTLTYPE_OPAQUE | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, sysctl_rss_key,
521 "", "RSS keying material");
524 sysctl_rss_bucket_mapping(SYSCTL_HANDLER_ARGS)
531 error = sysctl_wire_old_buffer(req, 0);
534 sb = sbuf_new_for_sysctl(NULL, NULL, 512, req);
537 for (i = 0; i < rss_buckets; i++) {
538 sbuf_printf(sb, "%s%d:%d", i == 0 ? "" : " ",
542 error = sbuf_finish(sb);
547 SYSCTL_PROC(_net_inet_rss, OID_AUTO, bucket_mapping,
548 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
549 sysctl_rss_bucket_mapping, "", "RSS bucket -> CPU mapping");