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 has 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/socket.h>
   77 #include <sys/socketvar.h>
   78 #include <sys/sysctl.h>
   79 
   80 #include <net/if.h>
   81 
   82 #include <netinet/in.h>
   83 #include <netinet/in_systm.h>
   84 #include <netinet/ip.h>
   85 #include <netinet/in_var.h>
   86 #include <netinet/in_pcb.h>
   87 #include <netinet/ip_var.h>
   88 #ifdef INET6
   89 #include <netinet/ip6.h>
   90 #include <netinet6/ip6_var.h>
   91 #endif
   92 #include <netinet/tcp.h>
   93 #include <netinet/tcp_var.h>
   94 #ifdef INET6
   95 #include <netinet6/tcp6_var.h>
   96 #endif
   97 
   98 #include <vm/uma.h>
   99 
  100 
  101 TAILQ_HEAD(hc_qhead, hc_metrics);
  102 
  103 struct hc_head {
  104         struct hc_qhead hch_bucket;
  105         u_int           hch_length;
  106         struct mtx      hch_mtx;
  107 };
  108 
  109 struct hc_metrics {
  110         /* housekeeping */
  111         TAILQ_ENTRY(hc_metrics) rmx_q;
  112         struct  hc_head *rmx_head; /* head of bucket tail queue */
  113         struct  in_addr ip4;    /* IP address */
  114         struct  in6_addr ip6;   /* IP6 address */
  115         /* endpoint specific values for TCP */
  116         u_long  rmx_mtu;        /* MTU for this path */
  117         u_long  rmx_ssthresh;   /* outbound gateway buffer limit */
  118         u_long  rmx_rtt;        /* estimated round trip time */
  119         u_long  rmx_rttvar;     /* estimated rtt variance */
  120         u_long  rmx_bandwidth;  /* estimated bandwidth */
  121         u_long  rmx_cwnd;       /* congestion window */
  122         u_long  rmx_sendpipe;   /* outbound delay-bandwidth product */
  123         u_long  rmx_recvpipe;   /* inbound delay-bandwidth product */
  124         /* TCP hostcache internal data */
  125         int     rmx_expire;     /* lifetime for object */
  126         u_long  rmx_hits;       /* number of hits */
  127         u_long  rmx_updates;    /* number of updates */
  128 };
  129 
  130 /* Arbitrary values */
  131 #define TCP_HOSTCACHE_HASHSIZE          512
  132 #define TCP_HOSTCACHE_BUCKETLIMIT       30
  133 #define TCP_HOSTCACHE_EXPIRE            60*60   /* one hour */
  134 #define TCP_HOSTCACHE_PRUNE             5*60    /* every 5 minutes */
  135 
  136 struct tcp_hostcache {
  137         struct  hc_head *hashbase;
  138         uma_zone_t zone;
  139         u_int   hashsize;
  140         u_int   hashmask;
  141         u_int   bucket_limit;
  142         u_int   cache_count;
  143         u_int   cache_limit;
  144         int     expire;
  145         int     prune;
  146         int     purgeall;
  147 };
  148 static struct tcp_hostcache tcp_hostcache;
  149 
  150 static struct callout tcp_hc_callout;
  151 
  152 static struct hc_metrics *tcp_hc_lookup(struct in_conninfo *);
  153 static struct hc_metrics *tcp_hc_insert(struct in_conninfo *);
  154 static int sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS);
  155 static void tcp_hc_purge(void *);
  156 
  157 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, hostcache, CTLFLAG_RW, 0, "TCP Host cache");
  158 
  159 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, cachelimit, CTLFLAG_RDTUN,
  160     &tcp_hostcache.cache_limit, 0, "Overall entry limit for hostcache");
  161 
  162 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, hashsize, CTLFLAG_RDTUN,
  163     &tcp_hostcache.hashsize, 0, "Size of TCP hostcache hashtable");
  164 
  165 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, bucketlimit, CTLFLAG_RDTUN,
  166     &tcp_hostcache.bucket_limit, 0, "Per-bucket hash limit for hostcache");
  167 
  168 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, count, CTLFLAG_RD,
  169     &tcp_hostcache.cache_count, 0, "Current number of entries in hostcache");
  170 
  171 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, expire, CTLFLAG_RW,
  172     &tcp_hostcache.expire, 0, "Expire time of TCP hostcache entries");
  173 
  174 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, prune, CTLFLAG_RW,
  175      &tcp_hostcache.prune, 0, "Time between purge runs");
  176 
  177 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, purge, CTLFLAG_RW,
  178     &tcp_hostcache.purgeall, 0, "Expire all entires on next purge run");
  179 
  180 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, list,
  181     CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP, 0, 0,
  182     sysctl_tcp_hc_list, "A", "List of all hostcache entries");
  183 
  184 
  185 static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache");
  186 
  187 #define HOSTCACHE_HASH(ip) \
  188         (((ip)->s_addr ^ ((ip)->s_addr >> 7) ^ ((ip)->s_addr >> 17)) &  \
  189           tcp_hostcache.hashmask)
  190 
  191 /* XXX: What is the recommended hash to get good entropy for IPv6 addresses? */
  192 #define HOSTCACHE_HASH6(ip6)                            \
  193         (((ip6)->s6_addr32[0] ^                         \
  194           (ip6)->s6_addr32[1] ^                         \
  195           (ip6)->s6_addr32[2] ^                         \
  196           (ip6)->s6_addr32[3]) &                        \
  197          tcp_hostcache.hashmask)
  198 
  199 #define THC_LOCK(lp)            mtx_lock(lp)
  200 #define THC_UNLOCK(lp)          mtx_unlock(lp)
  201 
  202 void
  203 tcp_hc_init(void)
  204 {
  205         int i;
  206 
  207         /*
  208          * Initialize hostcache structures.
  209          */
  210         tcp_hostcache.cache_count = 0;
  211         tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE;
  212         tcp_hostcache.bucket_limit = TCP_HOSTCACHE_BUCKETLIMIT;
  213         tcp_hostcache.cache_limit =
  214             tcp_hostcache.hashsize * tcp_hostcache.bucket_limit;
  215         tcp_hostcache.expire = TCP_HOSTCACHE_EXPIRE;
  216         tcp_hostcache.prune = TCP_HOSTCACHE_PRUNE;
  217 
  218         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.hashsize",
  219             &tcp_hostcache.hashsize);
  220         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.cachelimit",
  221             &tcp_hostcache.cache_limit);
  222         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.bucketlimit",
  223             &tcp_hostcache.bucket_limit);
  224         if (!powerof2(tcp_hostcache.hashsize)) {
  225                 printf("WARNING: hostcache hash size is not a power of 2.\n");
  226                 tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE; /* default */
  227         }
  228         tcp_hostcache.hashmask = tcp_hostcache.hashsize - 1;
  229 
  230         /*
  231          * Allocate the hash table.
  232          */
  233         tcp_hostcache.hashbase = (struct hc_head *)
  234             malloc(tcp_hostcache.hashsize * sizeof(struct hc_head),
  235                    M_HOSTCACHE, M_WAITOK | M_ZERO);
  236 
  237         /*
  238          * Initialize the hash buckets.
  239          */
  240         for (i = 0; i < tcp_hostcache.hashsize; i++) {
  241                 TAILQ_INIT(&tcp_hostcache.hashbase[i].hch_bucket);
  242                 tcp_hostcache.hashbase[i].hch_length = 0;
  243                 mtx_init(&tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry",
  244                           NULL, MTX_DEF);
  245         }
  246 
  247         /*
  248          * Allocate the hostcache entries.
  249          */
  250         tcp_hostcache.zone = uma_zcreate("hostcache", sizeof(struct hc_metrics),
  251             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
  252         uma_zone_set_max(tcp_hostcache.zone, tcp_hostcache.cache_limit);
  253 
  254         /*
  255          * Set up periodic cache cleanup.
  256          */
  257         callout_init(&tcp_hc_callout, CALLOUT_MPSAFE);
  258         callout_reset(&tcp_hc_callout, tcp_hostcache.prune * hz, tcp_hc_purge, 0);
  259 }
  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 = &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 = &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 >= tcp_hostcache.bucket_limit ||
  352             tcp_hostcache.cache_count >= 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                 tcp_hostcache.hashbase[hash].hch_length--;
  369                 tcp_hostcache.cache_count--;
  370                 tcpstat.tcps_hc_bucketoverflow++;
  371 #if 0
  372                 uma_zfree(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(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 = tcp_hostcache.expire;
  395 
  396         /*
  397          * Put it upfront.
  398          */
  399         TAILQ_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
  400         tcp_hostcache.hashbase[hash].hch_length++;
  401         tcp_hostcache.cache_count++;
  402         tcpstat.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 = 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 = 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 = 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 = 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.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.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.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.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.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.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.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 bufsize;
  597         int linesize = 128;
  598         char *p, *buf;
  599         int len, i, error;
  600         struct hc_metrics *hc_entry;
  601 #ifdef INET6
  602         char ip6buf[INET6_ADDRSTRLEN];
  603 #endif
  604 
  605         bufsize = linesize * (tcp_hostcache.cache_count + 1);
  606 
  607         p = buf = (char *)malloc(bufsize, M_TEMP, M_WAITOK|M_ZERO);
  608 
  609         len = snprintf(p, linesize,
  610                 "\nIP address        MTU  SSTRESH      RTT   RTTVAR BANDWIDTH "
  611                 "    CWND SENDPIPE RECVPIPE HITS  UPD  EXP\n");
  612         p += len;
  613 
  614 #define msec(u) (((u) + 500) / 1000)
  615         for (i = 0; i < tcp_hostcache.hashsize; i++) {
  616                 THC_LOCK(&tcp_hostcache.hashbase[i].hch_mtx);
  617                 TAILQ_FOREACH(hc_entry, &tcp_hostcache.hashbase[i].hch_bucket,
  618                               rmx_q) {
  619                         len = snprintf(p, linesize,
  620                             "%-15s %5lu %8lu %6lums %6lums %9lu %8lu %8lu %8lu "
  621                             "%4lu %4lu %4i\n",
  622                             hc_entry->ip4.s_addr ? inet_ntoa(hc_entry->ip4) :
  623 #ifdef INET6
  624                                 ip6_sprintf(ip6buf, &hc_entry->ip6),
  625 #else
  626                                 "IPv6?",
  627 #endif
  628                             hc_entry->rmx_mtu,
  629                             hc_entry->rmx_ssthresh,
  630                             msec(hc_entry->rmx_rtt *
  631                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
  632                             msec(hc_entry->rmx_rttvar *
  633                                 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE))),
  634                             hc_entry->rmx_bandwidth * 8,
  635                             hc_entry->rmx_cwnd,
  636                             hc_entry->rmx_sendpipe,
  637                             hc_entry->rmx_recvpipe,
  638                             hc_entry->rmx_hits,
  639                             hc_entry->rmx_updates,
  640                             hc_entry->rmx_expire);
  641                         p += len;
  642                 }
  643                 THC_UNLOCK(&tcp_hostcache.hashbase[i].hch_mtx);
  644         }
  645 #undef msec
  646         error = SYSCTL_OUT(req, buf, p - buf);
  647         free(buf, M_TEMP);
  648         return(error);
  649 }
  650 
  651 /*
  652  * Expire and purge (old|all) entries in the tcp_hostcache.  Runs
  653  * periodically from the callout.
  654  */
  655 static void
  656 tcp_hc_purge(void *arg)
  657 {
  658         struct hc_metrics *hc_entry, *hc_next;
  659         int all = (intptr_t)arg;
  660         int i;
  661 
  662         if (tcp_hostcache.purgeall) {
  663                 all = 1;
  664                 tcp_hostcache.purgeall = 0;
  665         }
  666 
  667         for (i = 0; i < tcp_hostcache.hashsize; i++) {
  668                 THC_LOCK(&tcp_hostcache.hashbase[i].hch_mtx);
  669                 TAILQ_FOREACH_SAFE(hc_entry, &tcp_hostcache.hashbase[i].hch_bucket,
  670                               rmx_q, hc_next) {
  671                         if (all || hc_entry->rmx_expire <= 0) {
  672                                 TAILQ_REMOVE(&tcp_hostcache.hashbase[i].hch_bucket,
  673                                               hc_entry, rmx_q);
  674                                 uma_zfree(tcp_hostcache.zone, hc_entry);
  675                                 tcp_hostcache.hashbase[i].hch_length--;
  676                                 tcp_hostcache.cache_count--;
  677                         } else
  678                                 hc_entry->rmx_expire -= tcp_hostcache.prune;
  679                 }
  680                 THC_UNLOCK(&tcp_hostcache.hashbase[i].hch_mtx);
  681         }
  682         callout_reset(&tcp_hc_callout, tcp_hostcache.prune * hz, tcp_hc_purge, 0);
  683 }
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FreeBSD/Linux Kernel Cross Reference sys/netinet/tcp_hostcache.c

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