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, 0, "Receive-side steering");
87 * Toeplitz is the only required hash function in the RSS spec, so use it by
90 static u_int rss_hashalgo = RSS_HASH_TOEPLITZ;
91 SYSCTL_INT(_net_inet_rss, OID_AUTO, hashalgo, CTLFLAG_RDTUN, &rss_hashalgo, 0,
92 "RSS hash algorithm");
95 * Size of the indirection table; at most 128 entries per the RSS spec. We
96 * size it to at least 2 times the number of CPUs by default to allow useful
97 * rebalancing. If not set explicitly with a loader tunable, we tune based
98 * on the number of CPUs present.
100 * XXXRW: buckets might be better to use for the tunable than bits.
102 static u_int rss_bits;
103 SYSCTL_INT(_net_inet_rss, OID_AUTO, bits, CTLFLAG_RDTUN, &rss_bits, 0,
106 static u_int rss_mask;
107 SYSCTL_INT(_net_inet_rss, OID_AUTO, mask, CTLFLAG_RD, &rss_mask, 0,
110 static const u_int rss_maxbits = RSS_MAXBITS;
111 SYSCTL_INT(_net_inet_rss, OID_AUTO, maxbits, CTLFLAG_RD,
112 __DECONST(int *, &rss_maxbits), 0, "RSS maximum bits");
115 * RSS's own count of the number of CPUs it could be using for processing.
116 * Bounded to 64 by RSS constants.
118 static u_int rss_ncpus;
119 SYSCTL_INT(_net_inet_rss, OID_AUTO, ncpus, CTLFLAG_RD, &rss_ncpus, 0,
120 "Number of CPUs available to RSS");
122 #define RSS_MAXCPUS (1 << (RSS_MAXBITS - 1))
123 static const u_int rss_maxcpus = RSS_MAXCPUS;
124 SYSCTL_INT(_net_inet_rss, OID_AUTO, maxcpus, CTLFLAG_RD,
125 __DECONST(int *, &rss_maxcpus), 0, "RSS maximum CPUs that can be used");
128 * Variable exists just for reporting rss_bits in a user-friendly way.
130 static u_int rss_buckets;
131 SYSCTL_INT(_net_inet_rss, OID_AUTO, buckets, CTLFLAG_RD, &rss_buckets, 0,
135 * Base CPU number; devices will add this to all CPU numbers returned by the
136 * RSS indirection table. Currently unmodifable in FreeBSD.
138 static const u_int rss_basecpu;
139 SYSCTL_INT(_net_inet_rss, OID_AUTO, basecpu, CTLFLAG_RD,
140 __DECONST(int *, &rss_basecpu), 0, "RSS base CPU");
143 * Print verbose debugging messages.
148 SYSCTL_INT(_net_inet_rss, OID_AUTO, debug, CTLFLAG_RWTUN, &rss_debug, 0,
152 * RSS secret key, intended to prevent attacks on load-balancing. Its
153 * effectiveness may be limited by algorithm choice and available entropy
156 * XXXRW: And that we don't randomize it yet!
158 * This is the default Microsoft RSS specification key which is also
159 * the Chelsio T5 firmware default key.
161 static uint8_t rss_key[RSS_KEYSIZE] = {
162 0x6d, 0x5a, 0x56, 0xda, 0x25, 0x5b, 0x0e, 0xc2,
163 0x41, 0x67, 0x25, 0x3d, 0x43, 0xa3, 0x8f, 0xb0,
164 0xd0, 0xca, 0x2b, 0xcb, 0xae, 0x7b, 0x30, 0xb4,
165 0x77, 0xcb, 0x2d, 0xa3, 0x80, 0x30, 0xf2, 0x0c,
166 0x6a, 0x42, 0xb7, 0x3b, 0xbe, 0xac, 0x01, 0xfa,
170 * RSS hash->CPU table, which maps hashed packet headers to particular CPUs.
171 * Drivers may supplement this table with a separate CPU<->queue table when
172 * programming devices.
174 struct rss_table_entry {
175 uint8_t rte_cpu; /* CPU affinity of bucket. */
177 static struct rss_table_entry rss_table[RSS_TABLE_MAXLEN];
180 rss_init(__unused void *arg)
186 * Validate tunables, coerce to sensible values.
188 switch (rss_hashalgo) {
189 case RSS_HASH_TOEPLITZ:
194 RSS_DEBUG("invalid RSS hashalgo %u, coercing to %u\n",
195 rss_hashalgo, RSS_HASH_TOEPLITZ);
196 rss_hashalgo = RSS_HASH_TOEPLITZ;
200 * Count available CPUs.
202 * XXXRW: Note incorrect assumptions regarding contiguity of this set
206 for (i = 0; i <= mp_maxid; i++) {
211 if (rss_ncpus > RSS_MAXCPUS)
212 rss_ncpus = RSS_MAXCPUS;
215 * Tune RSS table entries to be no less than 2x the number of CPUs
216 * -- unless we're running uniprocessor, in which case there's not
217 * much point in having buckets to rearrange for load-balancing!
221 rss_bits = fls(rss_ncpus - 1) + 1;
224 * Microsoft limits RSS table entries to 128, so apply that
225 * limit to both auto-detected CPU counts and user-configured
228 if (rss_bits == 0 || rss_bits > RSS_MAXBITS) {
229 RSS_DEBUG("RSS bits %u not valid, coercing to %u\n",
230 rss_bits, RSS_MAXBITS);
231 rss_bits = RSS_MAXBITS;
235 * Figure out how many buckets to use; warn if less than the
236 * number of configured CPUs, although this is not a fatal
239 rss_buckets = (1 << rss_bits);
240 if (rss_buckets < rss_ncpus)
241 RSS_DEBUG("WARNING: rss_buckets (%u) less than "
242 "rss_ncpus (%u)\n", rss_buckets, rss_ncpus);
243 rss_mask = rss_buckets - 1;
251 * Set up initial CPU assignments: round-robin by default.
254 for (i = 0; i < rss_buckets; i++) {
255 rss_table[i].rte_cpu = cpuid;
256 cpuid = CPU_NEXT(cpuid);
262 * XXXRW: Not yet. If nothing else, will require an rss_isbadkey()
263 * loop to check for "bad" RSS keys.
266 SYSINIT(rss_init, SI_SUB_SOFTINTR, SI_ORDER_SECOND, rss_init, NULL);
269 rss_naive_hash(u_int keylen, const uint8_t *key, u_int datalen,
276 for (i = 0; i < keylen; i++)
278 for (i = 0; i < datalen; i++)
284 rss_hash(u_int datalen, const uint8_t *data)
287 switch (rss_hashalgo) {
288 case RSS_HASH_TOEPLITZ:
289 return (toeplitz_hash(sizeof(rss_key), rss_key, datalen,
293 return (rss_naive_hash(sizeof(rss_key), rss_key, datalen,
297 panic("%s: unsupported/unknown hashalgo %d", __func__,
303 * Query the number of RSS bits in use.
313 * Query the RSS bucket associated with an RSS hash.
316 rss_getbucket(u_int hash)
319 return (hash & rss_mask);
323 * Query the RSS layer bucket associated with the given
324 * entry in the RSS hash space.
326 * The RSS indirection table is 0 .. rss_buckets-1,
327 * covering the low 'rss_bits' of the total 128 slot
328 * RSS indirection table. So just mask off rss_bits and
331 * NIC drivers can then iterate over the 128 slot RSS
332 * indirection table and fetch which RSS bucket to
333 * map it to. This will typically be a CPU queue
336 rss_get_indirection_to_bucket(u_int index)
339 return (index & rss_mask);
343 * Query the RSS CPU associated with an RSS bucket.
346 rss_getcpu(u_int bucket)
349 return (rss_table[bucket].rte_cpu);
353 * netisr CPU affinity lookup given just the hash and hashtype.
356 rss_hash2cpuid(uint32_t hash_val, uint32_t hash_type)
360 case M_HASHTYPE_RSS_IPV4:
361 case M_HASHTYPE_RSS_TCP_IPV4:
362 case M_HASHTYPE_RSS_UDP_IPV4:
363 case M_HASHTYPE_RSS_IPV6:
364 case M_HASHTYPE_RSS_TCP_IPV6:
365 case M_HASHTYPE_RSS_UDP_IPV6:
366 return (rss_getcpu(rss_getbucket(hash_val)));
368 return (NETISR_CPUID_NONE);
373 * Query the RSS bucket associated with the given hash value and
377 rss_hash2bucket(uint32_t hash_val, uint32_t hash_type, uint32_t *bucket_id)
381 case M_HASHTYPE_RSS_IPV4:
382 case M_HASHTYPE_RSS_TCP_IPV4:
383 case M_HASHTYPE_RSS_UDP_IPV4:
384 case M_HASHTYPE_RSS_IPV6:
385 case M_HASHTYPE_RSS_TCP_IPV6:
386 case M_HASHTYPE_RSS_UDP_IPV6:
387 *bucket_id = rss_getbucket(hash_val);
395 * netisr CPU affinity lookup routine for use by protocols.
398 rss_m2cpuid(struct mbuf *m, uintptr_t source, u_int *cpuid)
402 *cpuid = rss_hash2cpuid(m->m_pkthdr.flowid, M_HASHTYPE_GET(m));
407 rss_m2bucket(struct mbuf *m, uint32_t *bucket_id)
412 return(rss_hash2bucket(m->m_pkthdr.flowid, M_HASHTYPE_GET(m),
417 * Query the RSS hash algorithm.
420 rss_gethashalgo(void)
423 return (rss_hashalgo);
427 * Query the current RSS key; likely to be used by device drivers when
428 * configuring hardware RSS. Caller must pass an array of size RSS_KEYSIZE.
430 * XXXRW: Perhaps we should do the accept-a-length-and-truncate thing?
433 rss_getkey(uint8_t *key)
436 bcopy(rss_key, key, sizeof(rss_key));
440 * Query the number of buckets; this may be used by both network device
441 * drivers, which will need to populate hardware shadows of the software
442 * indirection table, and the network stack itself (such as when deciding how
443 * many connection groups to allocate).
446 rss_getnumbuckets(void)
449 return (rss_buckets);
453 * Query the number of CPUs in use by RSS; may be useful to device drivers
454 * trying to figure out how to map a larger number of CPUs into a smaller
455 * number of receive queues.
465 * Return the supported RSS hash configuration.
467 * NICs should query this to determine what to configure in their redirection
471 rss_gethashconfig(void)
474 /* Return 4-tuple for TCP; 2-tuple for others */
476 * UDP may fragment more often than TCP and thus we'll end up with
477 * NICs returning 2-tuple fragments.
478 * udp_init() and udplite_init() both currently initialise things
480 * So for now disable UDP 4-tuple hashing until all of the other
481 * pieces are in place.
484 RSS_HASHTYPE_RSS_IPV4
485 | RSS_HASHTYPE_RSS_TCP_IPV4
486 | RSS_HASHTYPE_RSS_IPV6
487 | RSS_HASHTYPE_RSS_TCP_IPV6
488 | RSS_HASHTYPE_RSS_IPV6_EX
489 | RSS_HASHTYPE_RSS_TCP_IPV6_EX
491 | RSS_HASHTYPE_RSS_UDP_IPV4
492 | RSS_HASHTYPE_RSS_UDP_IPV4_EX
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, NULL, 0,
554 sysctl_rss_bucket_mapping, "", "RSS bucket -> CPU mapping");