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f-stack/freebsd/netinet/in_pcbgroup.c

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/*-
* Copyright (c) 2010-2011 Juniper Networks, Inc.
* All rights reserved.
*
* This software was developed by Robert N. M. Watson under contract
* to Juniper Networks, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_inet6.h"
#include "opt_rss.h"
#include <sys/param.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/mutex.h>
#include <sys/smp.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <net/rss_config.h>
#include <netinet/in.h>
#include <netinet/in_pcb.h>
#include <netinet/in_rss.h>
#ifdef INET6
#include <netinet6/in6_pcb.h>
#endif /* INET6 */
/*
* pcbgroups, or "connection groups" are based on Willman, Rixner, and Cox's
* 2006 USENIX paper, "An Evaluation of Network Stack Parallelization
* Strategies in Modern Operating Systems". This implementation differs
* significantly from that described in the paper, in that it attempts to
* introduce not just notions of affinity for connections and distribute work
* so as to reduce lock contention, but also align those notions with
* hardware work distribution strategies such as RSS. In this construction,
* connection groups supplement, rather than replace, existing reservation
* tables for protocol 4-tuples, offering CPU-affine lookup tables with
* minimal cache line migration and lock contention during steady state
* operation.
*
* Hardware-offloaded checksums are often inefficient in software -- for
* example, Toeplitz, specified by RSS, introduced a significant overhead if
* performed during per-packge processing. It is therefore desirable to fall
* back on traditional reservation table lookups without affinity where
* hardware-offloaded checksums aren't available, such as for traffic over
* non-RSS interfaces.
*
* Internet protocols, such as UDP and TCP, register to use connection groups
* by providing an ipi_hashfields value other than IPI_HASHFIELDS_NONE; this
* indicates to the connection group code whether a 2-tuple or 4-tuple is
* used as an argument to hashes that assign a connection to a particular
* group. This must be aligned with any hardware offloaded distribution
* model, such as RSS or similar approaches taken in embedded network boards.
* Wildcard sockets require special handling, as in Willman 2006, and are
* shared between connection groups -- while being protected by group-local
* locks. This means that connection establishment and teardown can be
* signficantly more expensive than without connection groups, but that
* steady-state processing can be significantly faster.
*
* When RSS is used, certain connection group parameters, such as the number
* of groups, are provided by the RSS implementation, found in in_rss.c.
* Otherwise, in_pcbgroup.c selects possible sensible parameters
* corresponding to the degree of parallelism exposed by netisr.
*
* Most of the implementation of connection groups is in this file; however,
* connection group lookup is implemented in in_pcb.c alongside reservation
* table lookups -- see in_pcblookup_group().
*
* TODO:
*
* Implement dynamic rebalancing of buckets with connection groups; when
* load is unevenly distributed, search for more optimal balancing on
* demand. This might require scaling up the number of connection groups
* by <<1.
*
* Provide an IP 2-tuple or 4-tuple netisr m2cpu handler based on connection
* groups for ip_input and ip6_input, allowing non-offloaded work
* distribution.
*
* Expose effective CPU affinity of connections to userspace using socket
* options.
*
* Investigate per-connection affinity overrides based on socket options; an
* option could be set, certainly resulting in work being distributed
* differently in software, and possibly propagated to supporting hardware
* with TCAMs or hardware hash tables. This might require connections to
* exist in more than one connection group at a time.
*
* Hook netisr thread reconfiguration events, and propagate those to RSS so
* that rebalancing can occur when the thread pool grows or shrinks.
*
* Expose per-pcbgroup statistics to userspace monitoring tools such as
* netstat, in order to allow better debugging and profiling.
*/
void
in_pcbgroup_init(struct inpcbinfo *pcbinfo, u_int hashfields,
int hash_nelements)
{
struct inpcbgroup *pcbgroup;
u_int numpcbgroups, pgn;
/*
* Only enable connection groups for a protocol if it has been
* specifically requested.
*/
if (hashfields == IPI_HASHFIELDS_NONE)
return;
/*
* Connection groups are about multi-processor load distribution,
* lock contention, and connection CPU affinity. As such, no point
* in turning them on for a uniprocessor machine, it only wastes
* memory.
*/
if (mp_ncpus == 1)
return;
#ifdef RSS
/*
* If we're using RSS, then RSS determines the number of connection
* groups to use: one connection group per RSS bucket. If for some
* reason RSS isn't able to provide a number of buckets, disable
* connection groups entirely.
*
* XXXRW: Can this ever happen?
*/
numpcbgroups = rss_getnumbuckets();
if (numpcbgroups == 0)
return;
#else
/*
* Otherwise, we'll just use one per CPU for now. If we decide to
* do dynamic rebalancing a la RSS, we'll need similar logic here.
*/
numpcbgroups = mp_ncpus;
#endif
pcbinfo->ipi_hashfields = hashfields;
pcbinfo->ipi_pcbgroups = malloc(numpcbgroups *
sizeof(*pcbinfo->ipi_pcbgroups), M_PCB, M_WAITOK | M_ZERO);
pcbinfo->ipi_npcbgroups = numpcbgroups;
pcbinfo->ipi_wildbase = hashinit(hash_nelements, M_PCB,
&pcbinfo->ipi_wildmask);
for (pgn = 0; pgn < pcbinfo->ipi_npcbgroups; pgn++) {
pcbgroup = &pcbinfo->ipi_pcbgroups[pgn];
pcbgroup->ipg_hashbase = hashinit(hash_nelements, M_PCB,
&pcbgroup->ipg_hashmask);
INP_GROUP_LOCK_INIT(pcbgroup, "pcbgroup");
/*
* Initialise notional affinity of the pcbgroup -- for RSS,
* we want the same notion of affinity as NICs to be used. In
* the non-RSS case, just round robin for the time being.
*
* XXXRW: The notion of a bucket to CPU mapping is common at
* both pcbgroup and RSS layers -- does that mean that we
* should migrate it all from RSS to here, and just leave RSS
* responsible only for providing hashing and mapping funtions?
*/
#ifdef RSS
pcbgroup->ipg_cpu = rss_getcpu(pgn);
#else
pcbgroup->ipg_cpu = (pgn % mp_ncpus);
#endif
}
}
void
in_pcbgroup_destroy(struct inpcbinfo *pcbinfo)
{
struct inpcbgroup *pcbgroup;
u_int pgn;
if (pcbinfo->ipi_npcbgroups == 0)
return;
for (pgn = 0; pgn < pcbinfo->ipi_npcbgroups; pgn++) {
pcbgroup = &pcbinfo->ipi_pcbgroups[pgn];
KASSERT(LIST_EMPTY(pcbinfo->ipi_listhead),
("in_pcbinfo_destroy: listhead not empty"));
INP_GROUP_LOCK_DESTROY(pcbgroup);
hashdestroy(pcbgroup->ipg_hashbase, M_PCB,
pcbgroup->ipg_hashmask);
}
hashdestroy(pcbinfo->ipi_wildbase, M_PCB, pcbinfo->ipi_wildmask);
free(pcbinfo->ipi_pcbgroups, M_PCB);
pcbinfo->ipi_pcbgroups = NULL;
pcbinfo->ipi_npcbgroups = 0;
pcbinfo->ipi_hashfields = 0;
}
/*
* Given a hash of whatever the covered tuple might be, return a pcbgroup
* index. Where RSS is supported, try to align bucket selection with RSS CPU
* affinity strategy.
*/
static __inline u_int
in_pcbgroup_getbucket(struct inpcbinfo *pcbinfo, uint32_t hash)
{
#ifdef RSS
return (rss_getbucket(hash));
#else
return (hash % pcbinfo->ipi_npcbgroups);
#endif
}
/*
* Map a (hashtype, hash) tuple into a connection group, or NULL if the hash
* information is insufficient to identify the pcbgroup. This might occur if
* a TCP packet turns up with a 2-tuple hash, or if an RSS hash is present but
* RSS is not compiled into the kernel.
*/
struct inpcbgroup *
in_pcbgroup_byhash(struct inpcbinfo *pcbinfo, u_int hashtype, uint32_t hash)
{
#ifdef RSS
if ((pcbinfo->ipi_hashfields == IPI_HASHFIELDS_4TUPLE &&
hashtype == M_HASHTYPE_RSS_TCP_IPV4) ||
(pcbinfo->ipi_hashfields == IPI_HASHFIELDS_4TUPLE &&
hashtype == M_HASHTYPE_RSS_UDP_IPV4) ||
(pcbinfo->ipi_hashfields == IPI_HASHFIELDS_2TUPLE &&
hashtype == M_HASHTYPE_RSS_IPV4))
return (&pcbinfo->ipi_pcbgroups[
in_pcbgroup_getbucket(pcbinfo, hash)]);
#endif
return (NULL);
}
static struct inpcbgroup *
in_pcbgroup_bymbuf(struct inpcbinfo *pcbinfo, struct mbuf *m)
{
return (in_pcbgroup_byhash(pcbinfo, M_HASHTYPE_GET(m),
m->m_pkthdr.flowid));
}
struct inpcbgroup *
in_pcbgroup_bytuple(struct inpcbinfo *pcbinfo, struct in_addr laddr,
u_short lport, struct in_addr faddr, u_short fport)
{
uint32_t hash;
/*
* RSS note: we pass foreign addr/port as source, and local addr/port
* as destination, as we want to align with what the hardware is
* doing.
*/
switch (pcbinfo->ipi_hashfields) {
case IPI_HASHFIELDS_4TUPLE:
#ifdef RSS
hash = rss_hash_ip4_4tuple(faddr, fport, laddr, lport);
#else
hash = faddr.s_addr ^ fport;
#endif
break;
case IPI_HASHFIELDS_2TUPLE:
#ifdef RSS
hash = rss_hash_ip4_2tuple(faddr, laddr);
#else
hash = faddr.s_addr ^ laddr.s_addr;
#endif
break;
default:
hash = 0;
}
return (&pcbinfo->ipi_pcbgroups[in_pcbgroup_getbucket(pcbinfo,
hash)]);
}
struct inpcbgroup *
in_pcbgroup_byinpcb(struct inpcb *inp)
{
#ifdef RSS
/*
* Listen sockets with INP_RSS_BUCKET_SET set have a pre-determined
* RSS bucket and thus we should use this pcbgroup, rather than
* using a tuple or hash.
*
* XXX should verify that there's actually pcbgroups and inp_rss_listen_bucket
* fits in that!
*/
if (inp->inp_flags2 & INP_RSS_BUCKET_SET)
return (&inp->inp_pcbinfo->ipi_pcbgroups[inp->inp_rss_listen_bucket]);
#endif
return (in_pcbgroup_bytuple(inp->inp_pcbinfo, inp->inp_laddr,
inp->inp_lport, inp->inp_faddr, inp->inp_fport));
}
static void
in_pcbwild_add(struct inpcb *inp)
{
struct inpcbinfo *pcbinfo;
struct inpcbhead *head;
u_int pgn;
INP_WLOCK_ASSERT(inp);
KASSERT(!(inp->inp_flags2 & INP_PCBGROUPWILD),
("%s: is wild",__func__));
pcbinfo = inp->inp_pcbinfo;
for (pgn = 0; pgn < pcbinfo->ipi_npcbgroups; pgn++)
INP_GROUP_LOCK(&pcbinfo->ipi_pcbgroups[pgn]);
head = &pcbinfo->ipi_wildbase[INP_PCBHASH(INADDR_ANY, inp->inp_lport,
0, pcbinfo->ipi_wildmask)];
LIST_INSERT_HEAD(head, inp, inp_pcbgroup_wild);
inp->inp_flags2 |= INP_PCBGROUPWILD;
for (pgn = 0; pgn < pcbinfo->ipi_npcbgroups; pgn++)
INP_GROUP_UNLOCK(&pcbinfo->ipi_pcbgroups[pgn]);
}
static void
in_pcbwild_remove(struct inpcb *inp)
{
struct inpcbinfo *pcbinfo;
u_int pgn;
INP_WLOCK_ASSERT(inp);
KASSERT((inp->inp_flags2 & INP_PCBGROUPWILD),
("%s: not wild", __func__));
pcbinfo = inp->inp_pcbinfo;
for (pgn = 0; pgn < pcbinfo->ipi_npcbgroups; pgn++)
INP_GROUP_LOCK(&pcbinfo->ipi_pcbgroups[pgn]);
LIST_REMOVE(inp, inp_pcbgroup_wild);
for (pgn = 0; pgn < pcbinfo->ipi_npcbgroups; pgn++)
INP_GROUP_UNLOCK(&pcbinfo->ipi_pcbgroups[pgn]);
inp->inp_flags2 &= ~INP_PCBGROUPWILD;
}
static __inline int
in_pcbwild_needed(struct inpcb *inp)
{
#ifdef RSS
/*
* If it's a listen socket and INP_RSS_BUCKET_SET is set,
* it's a wildcard socket _but_ it's in a specific pcbgroup.
* Thus we don't treat it as a pcbwild inp.
*/
if (inp->inp_flags2 & INP_RSS_BUCKET_SET)
return (0);
#endif
#ifdef INET6
if (inp->inp_vflag & INP_IPV6)
return (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr));
else
#endif
return (inp->inp_faddr.s_addr == htonl(INADDR_ANY));
}
static void
in_pcbwild_update_internal(struct inpcb *inp)
{
int wildcard_needed;
wildcard_needed = in_pcbwild_needed(inp);
if (wildcard_needed && !(inp->inp_flags2 & INP_PCBGROUPWILD))
in_pcbwild_add(inp);
else if (!wildcard_needed && (inp->inp_flags2 & INP_PCBGROUPWILD))
in_pcbwild_remove(inp);
}
/*
* Update the pcbgroup of an inpcb, which might include removing an old
* pcbgroup reference and/or adding a new one. Wildcard processing is not
* performed here, although ideally we'll never install a pcbgroup for a
* wildcard inpcb (asserted below).
*/
static void
in_pcbgroup_update_internal(struct inpcbinfo *pcbinfo,
struct inpcbgroup *newpcbgroup, struct inpcb *inp)
{
struct inpcbgroup *oldpcbgroup;
struct inpcbhead *pcbhash;
uint32_t hashkey_faddr;
INP_WLOCK_ASSERT(inp);
oldpcbgroup = inp->inp_pcbgroup;
if (oldpcbgroup != NULL && oldpcbgroup != newpcbgroup) {
INP_GROUP_LOCK(oldpcbgroup);
LIST_REMOVE(inp, inp_pcbgrouphash);
inp->inp_pcbgroup = NULL;
INP_GROUP_UNLOCK(oldpcbgroup);
}
if (newpcbgroup != NULL && oldpcbgroup != newpcbgroup) {
#ifdef INET6
if (inp->inp_vflag & INP_IPV6)
hashkey_faddr = INP6_PCBHASHKEY(&inp->in6p_faddr);
else
#endif
hashkey_faddr = inp->inp_faddr.s_addr;
INP_GROUP_LOCK(newpcbgroup);
/*
* If the inp is an RSS bucket wildcard entry, ensure
* that the PCB hash is calculated correctly.
*
* The wildcard hash calculation differs from the
* non-wildcard definition. The source address is
* INADDR_ANY and the far port is 0.
*/
if (inp->inp_flags2 & INP_RSS_BUCKET_SET) {
pcbhash = &newpcbgroup->ipg_hashbase[
INP_PCBHASH(INADDR_ANY, inp->inp_lport, 0,
newpcbgroup->ipg_hashmask)];
} else {
pcbhash = &newpcbgroup->ipg_hashbase[
INP_PCBHASH(hashkey_faddr, inp->inp_lport,
inp->inp_fport,
newpcbgroup->ipg_hashmask)];
}
LIST_INSERT_HEAD(pcbhash, inp, inp_pcbgrouphash);
inp->inp_pcbgroup = newpcbgroup;
INP_GROUP_UNLOCK(newpcbgroup);
}
KASSERT(!(newpcbgroup != NULL && in_pcbwild_needed(inp)),
("%s: pcbgroup and wildcard!", __func__));
}
/*
* Two update paths: one in which the 4-tuple on an inpcb has been updated
* and therefore connection groups may need to change (or a wildcard entry
* may needed to be installed), and another in which the 4-tuple has been
* set as a result of a packet received, in which case we may be able to use
* the hash on the mbuf to avoid doing a software hash calculation for RSS.
*
* In each case: first, let the wildcard code have a go at placing it as a
* wildcard socket. If it was a wildcard, or if the connection has been
* dropped, then no pcbgroup is required (so potentially clear it);
* otherwise, calculate and update the pcbgroup for the inpcb.
*/
void
in_pcbgroup_update(struct inpcb *inp)
{
struct inpcbinfo *pcbinfo;
struct inpcbgroup *newpcbgroup;
INP_WLOCK_ASSERT(inp);
pcbinfo = inp->inp_pcbinfo;
if (!in_pcbgroup_enabled(pcbinfo))
return;
in_pcbwild_update_internal(inp);
if (!(inp->inp_flags2 & INP_PCBGROUPWILD) &&
!(inp->inp_flags & INP_DROPPED)) {
#ifdef INET6
if (inp->inp_vflag & INP_IPV6)
newpcbgroup = in6_pcbgroup_byinpcb(inp);
else
#endif
newpcbgroup = in_pcbgroup_byinpcb(inp);
} else
newpcbgroup = NULL;
in_pcbgroup_update_internal(pcbinfo, newpcbgroup, inp);
}
void
in_pcbgroup_update_mbuf(struct inpcb *inp, struct mbuf *m)
{
struct inpcbinfo *pcbinfo;
struct inpcbgroup *newpcbgroup;
INP_WLOCK_ASSERT(inp);
pcbinfo = inp->inp_pcbinfo;
if (!in_pcbgroup_enabled(pcbinfo))
return;
/*
* Possibly should assert !INP_PCBGROUPWILD rather than testing for
* it; presumably this function should never be called for anything
* other than non-wildcard socket?
*/
in_pcbwild_update_internal(inp);
if (!(inp->inp_flags2 & INP_PCBGROUPWILD) &&
!(inp->inp_flags & INP_DROPPED)) {
newpcbgroup = in_pcbgroup_bymbuf(pcbinfo, m);
#ifdef INET6
if (inp->inp_vflag & INP_IPV6) {
if (newpcbgroup == NULL)
newpcbgroup = in6_pcbgroup_byinpcb(inp);
} else {
#endif
if (newpcbgroup == NULL)
newpcbgroup = in_pcbgroup_byinpcb(inp);
#ifdef INET6
}
#endif
} else
newpcbgroup = NULL;
in_pcbgroup_update_internal(pcbinfo, newpcbgroup, inp);
}
/*
* Remove pcbgroup entry and optional pcbgroup wildcard entry for this inpcb.
*/
void
in_pcbgroup_remove(struct inpcb *inp)
{
struct inpcbgroup *pcbgroup;
INP_WLOCK_ASSERT(inp);
if (!in_pcbgroup_enabled(inp->inp_pcbinfo))
return;
if (inp->inp_flags2 & INP_PCBGROUPWILD)
in_pcbwild_remove(inp);
pcbgroup = inp->inp_pcbgroup;
if (pcbgroup != NULL) {
INP_GROUP_LOCK(pcbgroup);
LIST_REMOVE(inp, inp_pcbgrouphash);
inp->inp_pcbgroup = NULL;
INP_GROUP_UNLOCK(pcbgroup);
}
}
/*
* Query whether or not it is appropriate to use pcbgroups to look up inpcbs
* for a protocol.
*/
int
in_pcbgroup_enabled(struct inpcbinfo *pcbinfo)
{
return (pcbinfo->ipi_npcbgroups > 0);
}
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