tcp_hostcache.c

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    1 /*-
    2  * Copyright (c) 2002 Andre Oppermann, Internet Business Solutions AG
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 3. The name of the author may not be used to endorse or promote
   14  *    products derived from this software without specific prior written
   15  *    permission.
   16  *
   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
   27  * SUCH DAMAGE.
   28  */
   29 
   30 /*
   31  * The tcp_hostcache moves the tcp-specific cached metrics from the routing
   32  * table to a dedicated structure indexed by the remote IP address.  It keeps
   33  * information on the measured TCP parameters of past TCP sessions to allow
   34  * better initial start values to be used with later connections to/from the
   35  * same source.  Depending on the network parameters (delay, bandwidth, max
   36  * MTU, congestion window) between local and remote sites, this can lead to
   37  * significant speed-ups for new TCP connections after the first one.
   38  *
   39  * Due to the tcp_hostcache, all TCP-specific metrics information in the
   40  * routing table have been removed.  The inpcb no longer keeps a pointer to
   41  * the routing entry, and protocol-initiated route cloning has been removed
   42  * as well.  With these changes, the routing table has gone back to being
   43  * more lightwight and only carries information related to packet forwarding.
   44  *
   45  * tcp_hostcache is designed for multiple concurrent access in SMP
   46  * environments and high contention.  All bucket rows have their own lock and
   47  * thus multiple lookups and modifies can be done at the same time as long as
   48  * they are in different bucket rows.  If a request for insertion of a new
   49  * record can't be satisfied, it simply returns an empty structure.  Nobody
   50  * and nothing outside of tcp_hostcache.c will ever point directly to any
   51  * entry in the tcp_hostcache.  All communication is done in an
   52  * object-oriented way and only functions of tcp_hostcache will manipulate
   53  * hostcache entries.  Otherwise, we are unable to achieve good behaviour in
   54  * concurrent access situations.  Since tcp_hostcache is only caching
   55  * information, there are no fatal consequences if we either can't satisfy
   56  * any particular request or have to drop/overwrite an existing entry because
   57  * of bucket limit memory constrains.
   58  */
   59 
   60 /*
   61  * Many thanks to jlemon for basic structure of tcp_syncache which is being
   62  * followed here.
   63  */
   64 
   65 #include <sys/cdefs.h>
   66 __FBSDID("$FreeBSD$");
   67 
   68 #include "opt_inet6.h"
   69 
   70 #include <sys/param.h>
   71 #include <sys/systm.h>
   72 #include <sys/kernel.h>
   73 #include <sys/lock.h>
   74 #include <sys/mutex.h>
   75 #include <sys/malloc.h>
   76 #include <sys/sbuf.h>
   77 #include <sys/socket.h>
   78 #include <sys/socketvar.h>
   79 #include <sys/sysctl.h>
   80 
   81 #include <net/if.h>
   82 #include <net/route.h>
   83 #include <net/vnet.h>
   84 
   85 #include <netinet/in.h>
   86 #include <netinet/in_systm.h>
   87 #include <netinet/ip.h>
   88 #include <netinet/in_var.h>
   89 #include <netinet/in_pcb.h>
   90 #include <netinet/ip_var.h>
   91 #ifdef INET6
   92 #include <netinet/ip6.h>
   93 #include <netinet6/ip6_var.h>
   94 #endif
   95 #include <netinet/tcp.h>
   96 #include <netinet/tcp_var.h>
   97 #include <netinet/tcp_hostcache.h>
   98 #ifdef INET6
   99 #include <netinet6/tcp6_var.h>
  100 #endif
  101 
  102 #include <vm/uma.h>
  103 
  104 /* Arbitrary values */
  105 #define TCP_HOSTCACHE_HASHSIZE          512
  106 #define TCP_HOSTCACHE_BUCKETLIMIT       30
  107 #define TCP_HOSTCACHE_EXPIRE            60*60   /* one hour */
  108 #define TCP_HOSTCACHE_PRUNE             5*60    /* every 5 minutes */
  109 
  110 static VNET_DEFINE(struct tcp_hostcache, tcp_hostcache);
  111 #define V_tcp_hostcache         VNET(tcp_hostcache)
  112 
  113 static VNET_DEFINE(struct callout, tcp_hc_callout);
  114 #define V_tcp_hc_callout        VNET(tcp_hc_callout)
  115 
  116 static struct hc_metrics *tcp_hc_lookup(struct in_conninfo *);
  117 static struct hc_metrics *tcp_hc_insert(struct in_conninfo *);
  118 static int sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS);
  119 static void tcp_hc_purge_internal(int);
  120 static void tcp_hc_purge(void *);
  121 
  122 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, hostcache, CTLFLAG_RW, 0,
  123     "TCP Host cache");
  124 
  125 SYSCTL_VNET_UINT(_net_inet_tcp_hostcache, OID_AUTO, cachelimit, CTLFLAG_RDTUN,
  126     &VNET_NAME(tcp_hostcache.cache_limit), 0,
  127     "Overall entry limit for hostcache");
  128 
  129 SYSCTL_VNET_UINT(_net_inet_tcp_hostcache, OID_AUTO, hashsize, CTLFLAG_RDTUN,
  130     &VNET_NAME(tcp_hostcache.hashsize), 0,
  131     "Size of TCP hostcache hashtable");
  132 
  133 SYSCTL_VNET_UINT(_net_inet_tcp_hostcache, OID_AUTO, bucketlimit,
  134     CTLFLAG_RDTUN, &VNET_NAME(tcp_hostcache.bucket_limit), 0,
  135     "Per-bucket hash limit for hostcache");
  136 
  137 SYSCTL_VNET_UINT(_net_inet_tcp_hostcache, OID_AUTO, count, CTLFLAG_RD,
  138      &VNET_NAME(tcp_hostcache.cache_count), 0,
  139     "Current number of entries in hostcache");
  140 
  141 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, expire, CTLFLAG_RW,
  142     &VNET_NAME(tcp_hostcache.expire), 0,
  143     "Expire time of TCP hostcache entries");
  144 
  145 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, prune, CTLFLAG_RW,
  146     &VNET_NAME(tcp_hostcache.prune), 0,
  147     "Time between purge runs");
  148 
  149 SYSCTL_VNET_INT(_net_inet_tcp_hostcache, OID_AUTO, purge, CTLFLAG_RW,
  150     &VNET_NAME(tcp_hostcache.purgeall), 0,
  151     "Expire all entires on next purge run");
  152 
  153 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, list,
  154     CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP, 0, 0,
  155     sysctl_tcp_hc_list, "A", "List of all hostcache entries");
  156 
  157 
  158 static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache");
  159 
  160 #define HOSTCACHE_HASH(ip) \
  161         (((ip)->s_addr ^ ((ip)->s_addr >> 7) ^ ((ip)->s_addr >> 17)) &  \
  162           V_tcp_hostcache.hashmask)
  163 
  164 /* XXX: What is the recommended hash to get good entropy for IPv6 addresses? */
  165 #define HOSTCACHE_HASH6(ip6)                            \
  166         (((ip6)->s6_addr32[0] ^                         \
  167           (ip6)->s6_addr32[1] ^                         \
  168           (ip6)->s6_addr32[2] ^                         \
  169           (ip6)->s6_addr32[3]) &                        \
  170          V_tcp_hostcache.hashmask)
  171 
  172 #define THC_LOCK(lp)            mtx_lock(lp)
  173 #define THC_UNLOCK(lp)          mtx_unlock(lp)
  174 
  175 void
  176 tcp_hc_init(void)
  177 {
  178         u_int cache_limit;
  179         int i;
  180 
  181         /*
  182          * Initialize hostcache structures.
  183          */
  184         V_tcp_hostcache.cache_count = 0;
  185         V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE;
  186         V_tcp_hostcache.bucket_limit = TCP_HOSTCACHE_BUCKETLIMIT;
  187         V_tcp_hostcache.expire = TCP_HOSTCACHE_EXPIRE;
  188         V_tcp_hostcache.prune = TCP_HOSTCACHE_PRUNE;
  189 
  190         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.hashsize",
  191             &V_tcp_hostcache.hashsize);
  192         if (!powerof2(V_tcp_hostcache.hashsize)) {
  193                 printf("WARNING: hostcache hash size is not a power of 2.\n");
  194                 V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE; /* default */
  195         }
  196         V_tcp_hostcache.hashmask = V_tcp_hostcache.hashsize - 1;
  197 
  198         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.bucketlimit",
  199             &V_tcp_hostcache.bucket_limit);
  200 
  201         cache_limit = V_tcp_hostcache.hashsize * V_tcp_hostcache.bucket_limit;
  202         V_tcp_hostcache.cache_limit = cache_limit;
  203         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.cachelimit",
  204             &V_tcp_hostcache.cache_limit);
  205         if (V_tcp_hostcache.cache_limit > cache_limit)
  206                 V_tcp_hostcache.cache_limit = cache_limit;
  207 
  208         /*
  209          * Allocate the hash table.
  210          */
  211         V_tcp_hostcache.hashbase = (struct hc_head *)
  212             malloc(V_tcp_hostcache.hashsize * sizeof(struct hc_head),
  213                    M_HOSTCACHE, M_WAITOK | M_ZERO);
  214 
  215         /*
  216          * Initialize the hash buckets.
  217          */
  218         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
  219                 TAILQ_INIT(&V_tcp_hostcache.hashbase[i].hch_bucket);
  220                 V_tcp_hostcache.hashbase[i].hch_length = 0;
  221                 mtx_init(&V_tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry",
  222                           NULL, MTX_DEF);
  223         }
  224 
  225         /*
  226          * Allocate the hostcache entries.
  227          */
  228         V_tcp_hostcache.zone =
  229             uma_zcreate("hostcache", sizeof(struct hc_metrics),
  230             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
  231         uma_zone_set_max(V_tcp_hostcache.zone, V_tcp_hostcache.cache_limit);
  232 
  233         /*
  234          * Set up periodic cache cleanup.
  235          */
  236         callout_init(&V_tcp_hc_callout, CALLOUT_MPSAFE);
  237         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
  238             tcp_hc_purge, curvnet);
  239 }
  240 
  241 #ifdef VIMAGE
  242 void
  243 tcp_hc_destroy(void)
  244 {
  245         int i;
  246 
  247         callout_drain(&V_tcp_hc_callout);
  248 
  249         /* Purge all hc entries. */
  250         tcp_hc_purge_internal(1);
  251 
  252         /* Free the uma zone and the allocated hash table. */
  253         uma_zdestroy(V_tcp_hostcache.zone);
  254 
  255         for (i = 0; i < V_tcp_hostcache.hashsize; i++)
  256                 mtx_destroy(&V_tcp_hostcache.hashbase[i].hch_mtx);
  257         free(V_tcp_hostcache.hashbase, M_HOSTCACHE);
  258 }
  259 #endif
  260 
  261 /*
  262  * Internal function: look up an entry in the hostcache or return NULL.
  263  *
  264  * If an entry has been returned, the caller becomes responsible for
  265  * unlocking the bucket row after he is done reading/modifying the entry.
  266  */
  267 static struct hc_metrics *
  268 tcp_hc_lookup(struct in_conninfo *inc)
  269 {
  270         int hash;
  271         struct hc_head *hc_head;
  272         struct hc_metrics *hc_entry;
  273 
  274         KASSERT(inc != NULL, ("tcp_hc_lookup with NULL in_conninfo pointer"));
  275 
  276         /*
  277          * Hash the foreign ip address.
  278          */
  279         if (inc->inc_flags & INC_ISIPV6)
  280                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
  281         else
  282                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
  283 
  284         hc_head = &V_tcp_hostcache.hashbase[hash];
  285 
  286         /*
  287          * Acquire lock for this bucket row; we release the lock if we don't
  288          * find an entry, otherwise the caller has to unlock after he is
  289          * done.
  290          */
  291         THC_LOCK(&hc_head->hch_mtx);
  292 
  293         /*
  294          * Iterate through entries in bucket row looking for a match.
  295          */
  296         TAILQ_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q) {
  297                 if (inc->inc_flags & INC_ISIPV6) {
  298                         if (memcmp(&inc->inc6_faddr, &hc_entry->ip6,
  299                             sizeof(inc->inc6_faddr)) == 0)
  300                                 return hc_entry;
  301                 } else {
  302                         if (memcmp(&inc->inc_faddr, &hc_entry->ip4,
  303                             sizeof(inc->inc_faddr)) == 0)
  304                                 return hc_entry;
  305                 }
  306         }
  307 
  308         /*
  309          * We were unsuccessful and didn't find anything.
  310          */
  311         THC_UNLOCK(&hc_head->hch_mtx);
  312         return NULL;
  313 }
  314 
  315 /*
  316  * Internal function: insert an entry into the hostcache or return NULL if
  317  * unable to allocate a new one.
  318  *
  319  * If an entry has been returned, the caller becomes responsible for
  320  * unlocking the bucket row after he is done reading/modifying the entry.
  321  */
  322 static struct hc_metrics *
  323 tcp_hc_insert(struct in_conninfo *inc)
  324 {
  325         int hash;
  326         struct hc_head *hc_head;
  327         struct hc_metrics *hc_entry;
  328 
  329         KASSERT(inc != NULL, ("tcp_hc_insert with NULL in_conninfo pointer"));
  330 
  331         /*
  332          * Hash the foreign ip address.
  333          */
  334         if (inc->inc_flags & INC_ISIPV6)
  335                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
  336         else
  337                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
  338 
  339         hc_head = &V_tcp_hostcache.hashbase[hash];
  340 
  341         /*
  342          * Acquire lock for this bucket row; we release the lock if we don't
  343          * find an entry, otherwise the caller has to unlock after he is
  344          * done.
  345          */
  346         THC_LOCK(&hc_head->hch_mtx);
  347 
  348         /*
  349          * If the bucket limit is reached, reuse the least-used element.
  350          */
  351         if (hc_head->hch_length >= V_tcp_hostcache.bucket_limit ||
  352             V_tcp_hostcache.cache_count >= V_tcp_hostcache.cache_limit) {
  353                 hc_entry = TAILQ_LAST(&hc_head->hch_bucket, hc_qhead);
  354                 /*
  355                  * At first we were dropping the last element, just to
  356                  * reacquire it in the next two lines again, which isn't very
  357                  * efficient.  Instead just reuse the least used element.
  358                  * We may drop something that is still "in-use" but we can be
  359                  * "lossy".
  360                  * Just give up if this bucket row is empty and we don't have
  361                  * anything to replace.
  362                  */
  363                 if (hc_entry == NULL) {
  364                         THC_UNLOCK(&hc_head->hch_mtx);
  365                         return NULL;
  366                 }
  367                 TAILQ_REMOVE(&hc_head->hch_bucket, hc_entry, rmx_q);
  368                 V_tcp_hostcache.hashbase[hash].hch_length--;
  369                 V_tcp_hostcache.cache_count--;
  370                 TCPSTAT_INC(tcps_hc_bucketoverflow);
  371 #if 0
  372                 uma_zfree(V_tcp_hostcache.zone, hc_entry);
  373 #endif
  374         } else {
  375                 /*
  376                  * Allocate a new entry, or balk if not possible.
  377                  */
  378                 hc_entry = uma_zalloc(V_tcp_hostcache.zone, M_NOWAIT);
  379                 if (hc_entry == NULL) {
  380                         THC_UNLOCK(&hc_head->hch_mtx);
  381                         return NULL;
  382                 }
  383         }
  384 
  385         /*
  386          * Initialize basic information of hostcache entry.
  387          */
  388         bzero(hc_entry, sizeof(*hc_entry));
  389         if (inc->inc_flags & INC_ISIPV6)
  390                 bcopy(&inc->inc6_faddr, &hc_entry->ip6, sizeof(hc_entry->ip6));
  391         else
  392                 hc_entry->ip4 = inc->inc_faddr;
  393         hc_entry->rmx_head = hc_head;
  394         hc_entry->rmx_expire = V_tcp_hostcache.expire;
  395 
  396         /*
  397          * Put it upfront.
  398          */
  399         TAILQ_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
  400         V_tcp_hostcache.hashbase[hash].hch_length++;
  401         V_tcp_hostcache.cache_count++;
  402         TCPSTAT_INC(tcps_hc_added);
  403 
  404         return hc_entry;
  405 }
  406 
  407 /*
  408  * External function: look up an entry in the hostcache and fill out the
  409  * supplied TCP metrics structure.  Fills in NULL when no entry was found or
  410  * a value is not set.
  411  */
  412 void
  413 tcp_hc_get(struct in_conninfo *inc, struct hc_metrics_lite *hc_metrics_lite)
  414 {
  415         struct hc_metrics *hc_entry;
  416 
  417         /*
  418          * Find the right bucket.
  419          */
  420         hc_entry = tcp_hc_lookup(inc);
  421 
  422         /*
  423          * If we don't have an existing object.
  424          */
  425         if (hc_entry == NULL) {
  426                 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
  427                 return;
  428         }
  429         hc_entry->rmx_hits++;
  430         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
  431 
  432         hc_metrics_lite->rmx_mtu = hc_entry->rmx_mtu;
  433         hc_metrics_lite->rmx_ssthresh = hc_entry->rmx_ssthresh;
  434         hc_metrics_lite->rmx_rtt = hc_entry->rmx_rtt;
  435         hc_metrics_lite->rmx_rttvar = hc_entry->rmx_rttvar;
  436         hc_metrics_lite->rmx_bandwidth = hc_entry->rmx_bandwidth;
  437         hc_metrics_lite->rmx_cwnd = hc_entry->rmx_cwnd;
  438         hc_metrics_lite->rmx_sendpipe = hc_entry->rmx_sendpipe;
  439         hc_metrics_lite->rmx_recvpipe = hc_entry->rmx_recvpipe;
  440 
  441         /*
  442          * Unlock bucket row.
  443          */
  444         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
  445 }
  446 
  447 /*
  448  * External function: look up an entry in the hostcache and return the
  449  * discovered path MTU.  Returns NULL if no entry is found or value is not
  450  * set.
  451  */
  452 u_long
  453 tcp_hc_getmtu(struct in_conninfo *inc)
  454 {
  455         struct hc_metrics *hc_entry;
  456         u_long mtu;
  457 
  458         hc_entry = tcp_hc_lookup(inc);
  459         if (hc_entry == NULL) {
  460                 return 0;
  461         }
  462         hc_entry->rmx_hits++;
  463         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
  464 
  465         mtu = hc_entry->rmx_mtu;
  466         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
  467         return mtu;
  468 }
  469 
  470 /*
  471  * External function: update the MTU value of an entry in the hostcache.
  472  * Creates a new entry if none was found.
  473  */
  474 void
  475 tcp_hc_updatemtu(struct in_conninfo *inc, u_long mtu)
  476 {
  477         struct hc_metrics *hc_entry;
  478 
  479         /*
  480          * Find the right bucket.
  481          */
  482         hc_entry = tcp_hc_lookup(inc);
  483 
  484         /*
  485          * If we don't have an existing object, try to insert a new one.
  486          */
  487         if (hc_entry == NULL) {
  488                 hc_entry = tcp_hc_insert(inc);
  489                 if (hc_entry == NULL)
  490                         return;
  491         }
  492         hc_entry->rmx_updates++;
  493         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
  494 
  495         hc_entry->rmx_mtu = mtu;
  496 
  497         /*
  498          * Put it upfront so we find it faster next time.
  499          */
  500         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
  501         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
  502 
  503         /*
  504          * Unlock bucket row.
  505          */
  506         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
  507 }
  508 
  509 /*
  510  * External function: update the TCP metrics of an entry in the hostcache.
  511  * Creates a new entry if none was found.
  512  */
  513 void
  514 tcp_hc_update(struct in_conninfo *inc, struct hc_metrics_lite *hcml)
  515 {
  516         struct hc_metrics *hc_entry;
  517 
  518         hc_entry = tcp_hc_lookup(inc);
  519         if (hc_entry == NULL) {
  520                 hc_entry = tcp_hc_insert(inc);
  521                 if (hc_entry == NULL)
  522                         return;
  523         }
  524         hc_entry->rmx_updates++;
  525         hc_entry->rmx_expire = V_tcp_hostcache.expire; /* start over again */
  526 
  527         if (hcml->rmx_rtt != 0) {
  528                 if (hc_entry->rmx_rtt == 0)
  529                         hc_entry->rmx_rtt = hcml->rmx_rtt;
  530                 else
  531                         hc_entry->rmx_rtt =
  532                             (hc_entry->rmx_rtt + hcml->rmx_rtt) / 2;
  533                 TCPSTAT_INC(tcps_cachedrtt);
  534         }
  535         if (hcml->rmx_rttvar != 0) {
  536                 if (hc_entry->rmx_rttvar == 0)
  537                         hc_entry->rmx_rttvar = hcml->rmx_rttvar;
  538                 else
  539                         hc_entry->rmx_rttvar =
  540                             (hc_entry->rmx_rttvar + hcml->rmx_rttvar) / 2;
  541                 TCPSTAT_INC(tcps_cachedrttvar);
  542         }
  543         if (hcml->rmx_ssthresh != 0) {
  544                 if (hc_entry->rmx_ssthresh == 0)
  545                         hc_entry->rmx_ssthresh = hcml->rmx_ssthresh;
  546                 else
  547                         hc_entry->rmx_ssthresh =
  548                             (hc_entry->rmx_ssthresh + hcml->rmx_ssthresh) / 2;
  549                 TCPSTAT_INC(tcps_cachedssthresh);
  550         }
  551         if (hcml->rmx_bandwidth != 0) {
  552                 if (hc_entry->rmx_bandwidth == 0)
  553                         hc_entry->rmx_bandwidth = hcml->rmx_bandwidth;
  554                 else
  555                         hc_entry->rmx_bandwidth =
  556                             (hc_entry->rmx_bandwidth + hcml->rmx_bandwidth) / 2;
  557                 /* TCPSTAT_INC(tcps_cachedbandwidth); */
  558         }
  559         if (hcml->rmx_cwnd != 0) {
  560                 if (hc_entry->rmx_cwnd == 0)
  561                         hc_entry->rmx_cwnd = hcml->rmx_cwnd;
  562                 else
  563                         hc_entry->rmx_cwnd =
  564                             (hc_entry->rmx_cwnd + hcml->rmx_cwnd) / 2;
  565                 /* TCPSTAT_INC(tcps_cachedcwnd); */
  566         }
  567         if (hcml->rmx_sendpipe != 0) {
  568                 if (hc_entry->rmx_sendpipe == 0)
  569                         hc_entry->rmx_sendpipe = hcml->rmx_sendpipe;
  570                 else
  571                         hc_entry->rmx_sendpipe =
  572                             (hc_entry->rmx_sendpipe + hcml->rmx_sendpipe) /2;
  573                 /* TCPSTAT_INC(tcps_cachedsendpipe); */
  574         }
  575         if (hcml->rmx_recvpipe != 0) {
  576                 if (hc_entry->rmx_recvpipe == 0)
  577                         hc_entry->rmx_recvpipe = hcml->rmx_recvpipe;
  578                 else
  579                         hc_entry->rmx_recvpipe =
  580                             (hc_entry->rmx_recvpipe + hcml->rmx_recvpipe) /2;
  581                 /* TCPSTAT_INC(tcps_cachedrecvpipe); */
  582         }
  583 
  584         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
  585         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
  586         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
  587 }
  588 
  589 /*
  590  * Sysctl function: prints the list and values of all hostcache entries in
  591  * unsorted order.
  592  */
  593 static int
  594 sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS)
  595 {
  596         int linesize = 128;
  597         struct sbuf sb;
  598         int i, error;
  599         struct hc_metrics *hc_entry;
  600 #ifdef INET6
  601         char ip6buf[INET6_ADDRSTRLEN];
  602 #endif
  603 
  604         sbuf_new(&sb, NULL, linesize * (V_tcp_hostcache.cache_count + 1),
  605             SBUF_FIXEDLEN);
  606 
  607         sbuf_printf(&sb,
  608                 "\nIP address        MTU  SSTRESH      RTT   RTTVAR BANDWIDTH "
  609                 "    CWND SENDPIPE RECVPIPE HITS  UPD  EXP\n");
  610 
  611 #define msec(u) (((u) + 500) / 1000)
  612         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
  613                 THC_LOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
  614                 TAILQ_FOREACH(hc_entry, &V_tcp_hostcache.hashbase[i].hch_bucket,
  615                               rmx_q) {
  616                         sbuf_printf(&sb,
  617                             "%-15s %5lu %8lu %6lums %6lums %9lu %8lu %8lu %8lu "
  618                             "%4lu %4lu %4i\n",
  619                             hc_entry->ip4.s_addr ? inet_ntoa(hc_entry->ip4) :
  620 #ifdef INET6
  621                                 ip6_sprintf(ip6buf, &hc_entry->ip6),
  622 #else
  623                                 "IPv6?",
  624 #endif
  625                             hc_entry->rmx_mtu,
  626                             hc_entry->rmx_ssthresh,
  627                             msec(hc_entry->rmx_rtt *
  628                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
  629                             msec(hc_entry->rmx_rttvar *
  630                                 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE))),
  631                             hc_entry->rmx_bandwidth * 8,
  632                             hc_entry->rmx_cwnd,
  633                             hc_entry->rmx_sendpipe,
  634                             hc_entry->rmx_recvpipe,
  635                             hc_entry->rmx_hits,
  636                             hc_entry->rmx_updates,
  637                             hc_entry->rmx_expire);
  638                 }
  639                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
  640         }
  641 #undef msec
  642         sbuf_finish(&sb);
  643         error = SYSCTL_OUT(req, sbuf_data(&sb), sbuf_len(&sb));
  644         sbuf_delete(&sb);
  645         return(error);
  646 }
  647 
  648 /*
  649  * Caller has to make sure the curvnet is set properly.
  650  */
  651 static void
  652 tcp_hc_purge_internal(int all)
  653 {
  654         struct hc_metrics *hc_entry, *hc_next;
  655         int i;
  656 
  657         for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
  658                 THC_LOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
  659                 TAILQ_FOREACH_SAFE(hc_entry,
  660                     &V_tcp_hostcache.hashbase[i].hch_bucket, rmx_q, hc_next) {
  661                         if (all || hc_entry->rmx_expire <= 0) {
  662                                 TAILQ_REMOVE(&V_tcp_hostcache.hashbase[i].hch_bucket,
  663                                               hc_entry, rmx_q);
  664                                 uma_zfree(V_tcp_hostcache.zone, hc_entry);
  665                                 V_tcp_hostcache.hashbase[i].hch_length--;
  666                                 V_tcp_hostcache.cache_count--;
  667                         } else
  668                                 hc_entry->rmx_expire -= V_tcp_hostcache.prune;
  669                 }
  670                 THC_UNLOCK(&V_tcp_hostcache.hashbase[i].hch_mtx);
  671         }
  672 }
  673 
  674 /*
  675  * Expire and purge (old|all) entries in the tcp_hostcache.  Runs
  676  * periodically from the callout.
  677  */
  678 static void
  679 tcp_hc_purge(void *arg)
  680 {
  681         CURVNET_SET((struct vnet *) arg);
  682         int all = 0;
  683 
  684         if (V_tcp_hostcache.purgeall) {
  685                 all = 1;
  686                 V_tcp_hostcache.purgeall = 0;
  687         }
  688 
  689         tcp_hc_purge_internal(all);
  690 
  691         callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
  692             tcp_hc_purge, arg);
  693         CURVNET_RESTORE();
  694 }
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FreeBSD/Linux Kernel Cross Reference sys/netinet/tcp_hostcache.c

FreeBSD/Linux Kernel Cross Reference
sys/netinet/tcp_hostcache.c
