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>
51 #include <net/if_var.h>
52 #include <net/netisr.h>
53 #include <net/rss_config.h>
54 #include <net/toeplitz.h>
57 * Operating system parts of receiver-side scaling (RSS), which allows
58 * network cards to direct flows to particular receive queues based on hashes
59 * of header tuples. This implementation aligns RSS buckets with connection
60 * groups at the TCP/IP layer, so each bucket is associated with exactly one
61 * group. As a result, the group lookup structures (and lock) should have an
62 * effective affinity with exactly one CPU.
64 * Network device drivers needing to configure RSS will query this framework
65 * for parameters, such as the current RSS key, hashing policies, number of
66 * bits, and indirection table mapping hashes to buckets and CPUs. They may
67 * provide their own supplementary information, such as queue<->CPU bindings.
68 * It is the responsibility of the network device driver to inject packets
69 * into the stack on as close to the right CPU as possible, if playing by RSS
74 * - Synchronization for rss_key and other future-configurable parameters.
75 * - Event handler drivers can register to pick up RSS configuration changes.
76 * - Should we allow rss_basecpu to be configured?
77 * - Randomize key on boot.
79 * - Statistics on how often there's a misalignment between hardware
80 * placement and pcbgroup expectations.
83 SYSCTL_DECL(_net_inet);
84 SYSCTL_NODE(_net_inet, OID_AUTO, rss, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
85 "Receive-side steering");
88 * Toeplitz is the only required hash function in the RSS spec, so use it by
91 static u_int rss_hashalgo = RSS_HASH_TOEPLITZ;
92 SYSCTL_INT(_net_inet_rss, OID_AUTO, hashalgo, CTLFLAG_RDTUN, &rss_hashalgo, 0,
93 "RSS hash algorithm");
96 * Size of the indirection table; at most 128 entries per the RSS spec. We
97 * size it to at least 2 times the number of CPUs by default to allow useful
98 * rebalancing. If not set explicitly with a loader tunable, we tune based
99 * on the number of CPUs present.
101 * XXXRW: buckets might be better to use for the tunable than bits.
103 static u_int rss_bits;
104 SYSCTL_INT(_net_inet_rss, OID_AUTO, bits, CTLFLAG_RDTUN, &rss_bits, 0,
107 static u_int rss_mask;
108 SYSCTL_INT(_net_inet_rss, OID_AUTO, mask, CTLFLAG_RD, &rss_mask, 0,
111 static const u_int rss_maxbits = RSS_MAXBITS;
112 SYSCTL_INT(_net_inet_rss, OID_AUTO, maxbits, CTLFLAG_RD,
113 __DECONST(int *, &rss_maxbits), 0, "RSS maximum bits");
116 * RSS's own count of the number of CPUs it could be using for processing.
117 * Bounded to 64 by RSS constants.
119 static u_int rss_ncpus;
120 SYSCTL_INT(_net_inet_rss, OID_AUTO, ncpus, CTLFLAG_RD, &rss_ncpus, 0,
121 "Number of CPUs available to RSS");
123 #define RSS_MAXCPUS (1 << (RSS_MAXBITS - 1))
124 static const u_int rss_maxcpus = RSS_MAXCPUS;
125 SYSCTL_INT(_net_inet_rss, OID_AUTO, maxcpus, CTLFLAG_RD,
126 __DECONST(int *, &rss_maxcpus), 0, "RSS maximum CPUs that can be used");
129 * Variable exists just for reporting rss_bits in a user-friendly way.
131 static u_int rss_buckets;
132 SYSCTL_INT(_net_inet_rss, OID_AUTO, buckets, CTLFLAG_RD, &rss_buckets, 0,
136 * Base CPU number; devices will add this to all CPU numbers returned by the
137 * RSS indirection table. Currently unmodifable in FreeBSD.
139 static const u_int rss_basecpu;
140 SYSCTL_INT(_net_inet_rss, OID_AUTO, basecpu, CTLFLAG_RD,
141 __DECONST(int *, &rss_basecpu), 0, "RSS base CPU");
144 * Print verbose debugging messages.
149 SYSCTL_INT(_net_inet_rss, OID_AUTO, debug, CTLFLAG_RWTUN, &rss_debug, 0,
153 * RSS secret key, intended to prevent attacks on load-balancing. Its
154 * effectiveness may be limited by algorithm choice and available entropy
157 * XXXRW: And that we don't randomize it yet!
159 * This is the default Microsoft RSS specification key which is also
160 * the Chelsio T5 firmware default key.
162 static uint8_t rss_key[RSS_KEYSIZE] = {
163 0x6d, 0x5a, 0x56, 0xda, 0x25, 0x5b, 0x0e, 0xc2,
164 0x41, 0x67, 0x25, 0x3d, 0x43, 0xa3, 0x8f, 0xb0,
165 0xd0, 0xca, 0x2b, 0xcb, 0xae, 0x7b, 0x30, 0xb4,
166 0x77, 0xcb, 0x2d, 0xa3, 0x80, 0x30, 0xf2, 0x0c,
167 0x6a, 0x42, 0xb7, 0x3b, 0xbe, 0xac, 0x01, 0xfa,
171 * RSS hash->CPU table, which maps hashed packet headers to particular CPUs.
172 * Drivers may supplement this table with a separate CPU<->queue table when
173 * programming devices.
175 struct rss_table_entry {
176 uint8_t rte_cpu; /* CPU affinity of bucket. */
178 static struct rss_table_entry rss_table[RSS_TABLE_MAXLEN];
181 rss_init(__unused void *arg)
187 * Validate tunables, coerce to sensible values.
189 switch (rss_hashalgo) {
190 case RSS_HASH_TOEPLITZ:
195 RSS_DEBUG("invalid RSS hashalgo %u, coercing to %u\n",
196 rss_hashalgo, RSS_HASH_TOEPLITZ);
197 rss_hashalgo = RSS_HASH_TOEPLITZ;
201 * Count available CPUs.
203 * XXXRW: Note incorrect assumptions regarding contiguity of this set
207 for (i = 0; i <= mp_maxid; i++) {
212 if (rss_ncpus > RSS_MAXCPUS)
213 rss_ncpus = RSS_MAXCPUS;
216 * Tune RSS table entries to be no less than 2x the number of CPUs
217 * -- unless we're running uniprocessor, in which case there's not
218 * much point in having buckets to rearrange for load-balancing!
222 rss_bits = fls(rss_ncpus - 1) + 1;
225 * Microsoft limits RSS table entries to 128, so apply that
226 * limit to both auto-detected CPU counts and user-configured
229 if (rss_bits == 0 || rss_bits > RSS_MAXBITS) {
230 RSS_DEBUG("RSS bits %u not valid, coercing to %u\n",
231 rss_bits, RSS_MAXBITS);
232 rss_bits = RSS_MAXBITS;
236 * Figure out how many buckets to use; warn if less than the
237 * number of configured CPUs, although this is not a fatal
240 rss_buckets = (1 << rss_bits);
241 if (rss_buckets < rss_ncpus)
242 RSS_DEBUG("WARNING: rss_buckets (%u) less than "
243 "rss_ncpus (%u)\n", rss_buckets, rss_ncpus);
244 rss_mask = rss_buckets - 1;
252 * Set up initial CPU assignments: round-robin by default.
255 for (i = 0; i < rss_buckets; i++) {
256 rss_table[i].rte_cpu = cpuid;
257 cpuid = CPU_NEXT(cpuid);
263 * XXXRW: Not yet. If nothing else, will require an rss_isbadkey()
264 * loop to check for "bad" RSS keys.
267 SYSINIT(rss_init, SI_SUB_SOFTINTR, SI_ORDER_SECOND, rss_init, NULL);
270 rss_naive_hash(u_int keylen, const uint8_t *key, u_int datalen,
277 for (i = 0; i < keylen; i++)
279 for (i = 0; i < datalen; i++)
285 rss_hash(u_int datalen, const uint8_t *data)
288 switch (rss_hashalgo) {
289 case RSS_HASH_TOEPLITZ:
290 return (toeplitz_hash(sizeof(rss_key), rss_key, datalen,
294 return (rss_naive_hash(sizeof(rss_key), rss_key, datalen,
298 panic("%s: unsupported/unknown hashalgo %d", __func__,
304 * Query the number of RSS bits in use.
314 * Query the RSS bucket associated with an RSS hash.
317 rss_getbucket(u_int hash)
320 return (hash & rss_mask);
324 * Query the RSS layer bucket associated with the given
325 * entry in the RSS hash space.
327 * The RSS indirection table is 0 .. rss_buckets-1,
328 * covering the low 'rss_bits' of the total 128 slot
329 * RSS indirection table. So just mask off rss_bits and
332 * NIC drivers can then iterate over the 128 slot RSS
333 * indirection table and fetch which RSS bucket to
334 * map it to. This will typically be a CPU queue
337 rss_get_indirection_to_bucket(u_int index)
340 return (index & rss_mask);
344 * Query the RSS CPU associated with an RSS bucket.
347 rss_getcpu(u_int bucket)
350 return (rss_table[bucket].rte_cpu);
354 * netisr CPU affinity lookup given just the hash and hashtype.
357 rss_hash2cpuid(uint32_t hash_val, uint32_t hash_type)
361 case M_HASHTYPE_RSS_IPV4:
362 case M_HASHTYPE_RSS_TCP_IPV4:
363 case M_HASHTYPE_RSS_UDP_IPV4:
364 case M_HASHTYPE_RSS_IPV6:
365 case M_HASHTYPE_RSS_TCP_IPV6:
366 case M_HASHTYPE_RSS_UDP_IPV6:
367 return (rss_getcpu(rss_getbucket(hash_val)));
369 return (NETISR_CPUID_NONE);
374 * Query the RSS bucket associated with the given hash value and
378 rss_hash2bucket(uint32_t hash_val, uint32_t hash_type, uint32_t *bucket_id)
382 case M_HASHTYPE_RSS_IPV4:
383 case M_HASHTYPE_RSS_TCP_IPV4:
384 case M_HASHTYPE_RSS_UDP_IPV4:
385 case M_HASHTYPE_RSS_IPV6:
386 case M_HASHTYPE_RSS_TCP_IPV6:
387 case M_HASHTYPE_RSS_UDP_IPV6:
388 *bucket_id = rss_getbucket(hash_val);
396 * netisr CPU affinity lookup routine for use by protocols.
399 rss_m2cpuid(struct mbuf *m, uintptr_t source, u_int *cpuid)
403 *cpuid = rss_hash2cpuid(m->m_pkthdr.flowid, M_HASHTYPE_GET(m));
408 rss_m2bucket(struct mbuf *m, uint32_t *bucket_id)
413 return(rss_hash2bucket(m->m_pkthdr.flowid, M_HASHTYPE_GET(m),
418 * Query the RSS hash algorithm.
421 rss_gethashalgo(void)
424 return (rss_hashalgo);
428 * Query the current RSS key; likely to be used by device drivers when
429 * configuring hardware RSS. Caller must pass an array of size RSS_KEYSIZE.
431 * XXXRW: Perhaps we should do the accept-a-length-and-truncate thing?
434 rss_getkey(uint8_t *key)
437 bcopy(rss_key, key, sizeof(rss_key));
441 * Query the number of buckets; this may be used by both network device
442 * drivers, which will need to populate hardware shadows of the software
443 * indirection table, and the network stack itself (such as when deciding how
444 * many connection groups to allocate).
447 rss_getnumbuckets(void)
450 return (rss_buckets);
454 * Query the number of CPUs in use by RSS; may be useful to device drivers
455 * trying to figure out how to map a larger number of CPUs into a smaller
456 * number of receive queues.
466 * Return the supported RSS hash configuration.
468 * NICs should query this to determine what to configure in their redirection
472 rss_gethashconfig(void)
475 /* Return 4-tuple for TCP; 2-tuple for others */
477 * UDP may fragment more often than TCP and thus we'll end up with
478 * NICs returning 2-tuple fragments.
479 * udp_init() and udplite_init() both currently initialise things
481 * So for now disable UDP 4-tuple hashing until all of the other
482 * pieces are in place.
485 RSS_HASHTYPE_RSS_IPV4
486 | RSS_HASHTYPE_RSS_TCP_IPV4
487 | RSS_HASHTYPE_RSS_IPV6
488 | RSS_HASHTYPE_RSS_TCP_IPV6
489 | RSS_HASHTYPE_RSS_IPV6_EX
490 | RSS_HASHTYPE_RSS_TCP_IPV6_EX
492 | RSS_HASHTYPE_RSS_UDP_IPV4
493 | RSS_HASHTYPE_RSS_UDP_IPV6
494 | RSS_HASHTYPE_RSS_UDP_IPV6_EX
500 * XXXRW: Confirm that sysctl -a won't dump this keying material, don't want
501 * it appearing in debugging output unnecessarily.
504 sysctl_rss_key(SYSCTL_HANDLER_ARGS)
506 uint8_t temp_rss_key[RSS_KEYSIZE];
509 error = priv_check(req->td, PRIV_NETINET_HASHKEY);
513 bcopy(rss_key, temp_rss_key, sizeof(temp_rss_key));
514 error = sysctl_handle_opaque(oidp, temp_rss_key,
515 sizeof(temp_rss_key), req);
518 if (req->newptr != NULL) {
519 /* XXXRW: Not yet. */
524 SYSCTL_PROC(_net_inet_rss, OID_AUTO, key,
525 CTLTYPE_OPAQUE | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, sysctl_rss_key,
526 "", "RSS keying material");
529 sysctl_rss_bucket_mapping(SYSCTL_HANDLER_ARGS)
536 error = sysctl_wire_old_buffer(req, 0);
539 sb = sbuf_new_for_sysctl(NULL, NULL, 512, req);
542 for (i = 0; i < rss_buckets; i++) {
543 sbuf_printf(sb, "%s%d:%d", i == 0 ? "" : " ",
547 error = sbuf_finish(sb);
552 SYSCTL_PROC(_net_inet_rss, OID_AUTO, bucket_mapping,
553 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
554 sysctl_rss_bucket_mapping, "", "RSS bucket -> CPU mapping");