The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netinet/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  * $FreeBSD: releng/6.0/sys/netinet/tcp_hostcache.c 139823 2005-01-07 01:45:51Z imp $
   30  */
   31 
   32 /*
   33  * The tcp_hostcache moves the tcp specific cached metrics from the routing
   34  * table into a dedicated structure indexed by the remote IP address. It
   35  * keeps information on the measured tcp parameters of past tcp sessions
   36  * to have better initial start values for following connections from the
   37  * same source. Depending on the network parameters (delay, bandwidth, max
   38  * MTU, congestion window) between local and remote site this can lead to
   39  * significant speedups for new tcp connections after the first one.
   40  *
   41  * Due to this new tcp_hostcache all tcp specific metrics information in
   42  * the routing table has been removed. The INPCB no longer keeps a pointer
   43  * to the routing entry and protocol initiated route cloning has been
   44  * removed as well. With these changes the routing table has gone back
   45  * to being more lightwight and only carries information related to packet
   46  * forwarding.
   47  *
   48  * Tcp_hostcache is designed for multiple concurrent access in SMP
   49  * environments and high contention. All bucket rows have their own
   50  * lock and thus multiple lookups and modifies can be done at the same
   51  * time as long as they are in different bucket rows. If a request for
   52  * insertion of a new record can't be satisfied it simply returns an
   53  * empty structure. Nobody and nothing shall ever point directly to
   54  * any entry in tcp_hostcache. All communication is done in an object
   55  * oriented way and only funtions of tcp_hostcache will manipulate hostcache
   56  * entries. Otherwise we are unable to achieve good behaviour in concurrent
   57  * access situations. Since tcp_hostcache is only caching information there
   58  * are no fatal consequences if we either can't satisfy any particular request
   59  * or have to drop/overwrite an existing entry because of bucket limit
   60  * memory constrains.
   61  */
   62 
   63 /*
   64  * Many thanks to jlemon for basic structure of tcp_syncache which is being
   65  * followed here.
   66  */
   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     purgeall;
  146 };
  147 static struct tcp_hostcache tcp_hostcache;
  148 
  149 static struct callout tcp_hc_callout;
  150 
  151 static struct hc_metrics *tcp_hc_lookup(struct in_conninfo *);
  152 static struct hc_metrics *tcp_hc_insert(struct in_conninfo *);
  153 static int sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS);
  154 static void tcp_hc_purge(void *);
  155 
  156 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, hostcache, CTLFLAG_RW, 0, "TCP Host cache");
  157 
  158 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, cachelimit, CTLFLAG_RDTUN,
  159      &tcp_hostcache.cache_limit, 0, "Overall entry limit for hostcache");
  160 
  161 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, hashsize, CTLFLAG_RDTUN,
  162      &tcp_hostcache.hashsize, 0, "Size of TCP hostcache hashtable");
  163 
  164 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, bucketlimit, CTLFLAG_RDTUN,
  165      &tcp_hostcache.bucket_limit, 0, "Per-bucket hash limit for hostcache");
  166 
  167 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, count, CTLFLAG_RD,
  168      &tcp_hostcache.cache_count, 0, "Current number of entries in hostcache");
  169 
  170 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, expire, CTLFLAG_RW,
  171      &tcp_hostcache.expire, 0, "Expire time of TCP hostcache entries");
  172 
  173 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, purge, CTLFLAG_RW,
  174      &tcp_hostcache.purgeall, 0, "Expire all entires on next purge run");
  175 
  176 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, list,
  177         CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP, 0, 0,
  178         sysctl_tcp_hc_list, "A", "List of all hostcache entries");
  179 
  180 
  181 static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache");
  182 
  183 #define HOSTCACHE_HASH(ip) \
  184         (((ip)->s_addr ^ ((ip)->s_addr >> 7) ^ ((ip)->s_addr >> 17)) &  \
  185           tcp_hostcache.hashmask)
  186 
  187 /* XXX: What is the recommended hash to get good entropy for IPv6 addresses? */
  188 #define HOSTCACHE_HASH6(ip6)                            \
  189         (((ip6)->s6_addr32[0] ^                         \
  190           (ip6)->s6_addr32[1] ^                         \
  191           (ip6)->s6_addr32[2] ^                         \
  192           (ip6)->s6_addr32[3]) &                        \
  193          tcp_hostcache.hashmask)
  194 
  195 #define THC_LOCK(lp)            mtx_lock(lp)
  196 #define THC_UNLOCK(lp)          mtx_unlock(lp)
  197 
  198 void
  199 tcp_hc_init(void)
  200 {
  201         int i;
  202 
  203         /*
  204          * Initialize hostcache structures
  205          */
  206         tcp_hostcache.cache_count = 0;
  207         tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE;
  208         tcp_hostcache.bucket_limit = TCP_HOSTCACHE_BUCKETLIMIT;
  209         tcp_hostcache.cache_limit =
  210             tcp_hostcache.hashsize * tcp_hostcache.bucket_limit;
  211         tcp_hostcache.expire = TCP_HOSTCACHE_EXPIRE;
  212 
  213         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.hashsize",
  214             &tcp_hostcache.hashsize);
  215         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.cachelimit",
  216             &tcp_hostcache.cache_limit);
  217         TUNABLE_INT_FETCH("net.inet.tcp.hostcache.bucketlimit",
  218             &tcp_hostcache.bucket_limit);
  219         if (!powerof2(tcp_hostcache.hashsize)) {
  220                 printf("WARNING: hostcache hash size is not a power of 2.\n");
  221                 tcp_hostcache.hashsize = 512;   /* safe default */
  222         }
  223         tcp_hostcache.hashmask = tcp_hostcache.hashsize - 1;
  224 
  225         /*
  226          * Allocate the hash table
  227          */
  228         tcp_hostcache.hashbase = (struct hc_head *)
  229             malloc(tcp_hostcache.hashsize * sizeof(struct hc_head),
  230                    M_HOSTCACHE, M_WAITOK | M_ZERO);
  231 
  232         /*
  233          * Initialize the hash buckets
  234          */
  235         for (i = 0; i < tcp_hostcache.hashsize; i++) {
  236                 TAILQ_INIT(&tcp_hostcache.hashbase[i].hch_bucket);
  237                 tcp_hostcache.hashbase[i].hch_length = 0;
  238                 mtx_init(&tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry",
  239                           NULL, MTX_DEF);
  240         }
  241 
  242         /*
  243          * Allocate the hostcache entries.
  244          */
  245         tcp_hostcache.zone = uma_zcreate("hostcache", sizeof(struct hc_metrics),
  246             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
  247         uma_zone_set_max(tcp_hostcache.zone, tcp_hostcache.cache_limit);
  248 
  249         /*
  250          * Set up periodic cache cleanup.
  251          */
  252         callout_init(&tcp_hc_callout, CALLOUT_MPSAFE);
  253         callout_reset(&tcp_hc_callout, TCP_HOSTCACHE_PRUNE * hz, tcp_hc_purge, 0);
  254 }
  255 
  256 /*
  257  * Internal function: lookup an entry in the hostcache or return NULL.
  258  *
  259  * If an entry has been returned, the caller becomes responsible for
  260  * unlocking the bucket row after he is done reading/modifying the entry.
  261  */
  262 static struct hc_metrics *
  263 tcp_hc_lookup(struct in_conninfo *inc)
  264 {
  265         int hash;
  266         struct hc_head *hc_head;
  267         struct hc_metrics *hc_entry;
  268 
  269         KASSERT(inc != NULL, ("tcp_hc_lookup with NULL in_conninfo pointer"));
  270 
  271         /*
  272          * Hash the foreign ip address.
  273          */
  274         if (inc->inc_isipv6)
  275                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
  276         else
  277                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
  278 
  279         hc_head = &tcp_hostcache.hashbase[hash];
  280 
  281         /*
  282          * aquire lock for this bucket row
  283          * we release the lock if we don't find an entry,
  284          * otherwise the caller has to unlock after he is done
  285          */
  286         THC_LOCK(&hc_head->hch_mtx);
  287 
  288         /*
  289          * circle through entries in bucket row looking for a match
  290          */
  291         TAILQ_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q) {
  292                 if (inc->inc_isipv6) {
  293                         if (memcmp(&inc->inc6_faddr, &hc_entry->ip6,
  294                             sizeof(inc->inc6_faddr)) == 0)
  295                                 return hc_entry;
  296                 } else {
  297                         if (memcmp(&inc->inc_faddr, &hc_entry->ip4,
  298                             sizeof(inc->inc_faddr)) == 0)
  299                                 return hc_entry;
  300                 }
  301         }
  302 
  303         /*
  304          * We were unsuccessful and didn't find anything
  305          */
  306         THC_UNLOCK(&hc_head->hch_mtx);
  307         return NULL;
  308 }
  309 
  310 /*
  311  * Internal function: insert an entry into the hostcache or return NULL
  312  * if unable to allocate a new one.
  313  *
  314  * If an entry has been returned, the caller becomes responsible for
  315  * unlocking the bucket row after he is done reading/modifying the entry.
  316  */
  317 static struct hc_metrics *
  318 tcp_hc_insert(struct in_conninfo *inc)
  319 {
  320         int hash;
  321         struct hc_head *hc_head;
  322         struct hc_metrics *hc_entry;
  323 
  324         KASSERT(inc != NULL, ("tcp_hc_insert with NULL in_conninfo pointer"));
  325 
  326         /*
  327          * Hash the foreign ip address
  328          */
  329         if (inc->inc_isipv6)
  330                 hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
  331         else
  332                 hash = HOSTCACHE_HASH(&inc->inc_faddr);
  333 
  334         hc_head = &tcp_hostcache.hashbase[hash];
  335 
  336         /*
  337          * aquire lock for this bucket row
  338          * we release the lock if we don't find an entry,
  339          * otherwise the caller has to unlock after he is done
  340          */
  341         THC_LOCK(&hc_head->hch_mtx);
  342 
  343         /*
  344          * If the bucket limit is reached reuse the least used element
  345          */
  346         if (hc_head->hch_length >= tcp_hostcache.bucket_limit ||
  347             tcp_hostcache.cache_count >= tcp_hostcache.cache_limit) {
  348                 hc_entry = TAILQ_LAST(&hc_head->hch_bucket, hc_qhead);
  349                 /*
  350                  * At first we were dropping the last element, just to
  351                  * reaquire it in the next two lines again which ain't
  352                  * very efficient. Instead just reuse the least used element.
  353                  * Maybe we drop something that is still "in-use" but we can
  354                  * be "lossy".
  355                  */
  356                 TAILQ_REMOVE(&hc_head->hch_bucket, hc_entry, rmx_q);
  357                 tcp_hostcache.hashbase[hash].hch_length--;
  358                 tcp_hostcache.cache_count--;
  359                 tcpstat.tcps_hc_bucketoverflow++;
  360 #if 0
  361                 uma_zfree(tcp_hostcache.zone, hc_entry);
  362 #endif
  363         } else {
  364                 /*
  365                  * Allocate a new entry, or balk if not possible
  366                  */
  367                 hc_entry = uma_zalloc(tcp_hostcache.zone, M_NOWAIT);
  368                 if (hc_entry == NULL) {
  369                         THC_UNLOCK(&hc_head->hch_mtx);
  370                         return NULL;
  371                 }
  372         }
  373 
  374         /*
  375          * Initialize basic information of hostcache entry
  376          */
  377         bzero(hc_entry, sizeof(*hc_entry));
  378         if (inc->inc_isipv6)
  379                 bcopy(&inc->inc6_faddr, &hc_entry->ip6, sizeof(hc_entry->ip6));
  380         else
  381                 hc_entry->ip4 = inc->inc_faddr;
  382         hc_entry->rmx_head = hc_head;
  383         hc_entry->rmx_expire = tcp_hostcache.expire;
  384 
  385         /*
  386          * Put it upfront
  387          */
  388         TAILQ_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
  389         tcp_hostcache.hashbase[hash].hch_length++;
  390         tcp_hostcache.cache_count++;
  391         tcpstat.tcps_hc_added++;
  392 
  393         return hc_entry;
  394 }
  395 
  396 /*
  397  * External function: lookup an entry in the hostcache and fill out the
  398  * supplied tcp metrics structure.  Fills in null when no entry was found
  399  * or a value is not set.
  400  */
  401 void
  402 tcp_hc_get(struct in_conninfo *inc, struct hc_metrics_lite *hc_metrics_lite)
  403 {
  404         struct hc_metrics *hc_entry;
  405 
  406         /*
  407          * Find the right bucket
  408          */
  409         hc_entry = tcp_hc_lookup(inc);
  410 
  411         /*
  412          * If we don't have an existing object
  413          */
  414         if (hc_entry == NULL) {
  415                 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
  416                 return;
  417         }
  418         hc_entry->rmx_hits++;
  419         hc_entry->rmx_expire = tcp_hostcache.expire; /* start over again */
  420 
  421         hc_metrics_lite->rmx_mtu = hc_entry->rmx_mtu;
  422         hc_metrics_lite->rmx_ssthresh = hc_entry->rmx_ssthresh;
  423         hc_metrics_lite->rmx_rtt = hc_entry->rmx_rtt;
  424         hc_metrics_lite->rmx_rttvar = hc_entry->rmx_rttvar;
  425         hc_metrics_lite->rmx_bandwidth = hc_entry->rmx_bandwidth;
  426         hc_metrics_lite->rmx_cwnd = hc_entry->rmx_cwnd;
  427         hc_metrics_lite->rmx_sendpipe = hc_entry->rmx_sendpipe;
  428         hc_metrics_lite->rmx_recvpipe = hc_entry->rmx_recvpipe;
  429 
  430         /*
  431          * unlock bucket row
  432          */
  433         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
  434 }
  435 
  436 /*
  437  * External function: lookup an entry in the hostcache and return the
  438  * discovered path mtu.  Returns null if no entry is found or value is not
  439  * set.
  440  */
  441 u_long
  442 tcp_hc_getmtu(struct in_conninfo *inc)
  443 {
  444         struct hc_metrics *hc_entry;
  445         u_long mtu;
  446 
  447         hc_entry = tcp_hc_lookup(inc);
  448         if (hc_entry == NULL) {
  449                 return 0;
  450         }
  451         hc_entry->rmx_hits++;
  452         hc_entry->rmx_expire = tcp_hostcache.expire; /* start over again */
  453 
  454         mtu = hc_entry->rmx_mtu;
  455         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
  456         return mtu;
  457 }
  458 
  459 /*
  460  * External function: update the mtu value of an entry in the hostcache.
  461  * Creates a new entry if none was found.
  462  */
  463 void
  464 tcp_hc_updatemtu(struct in_conninfo *inc, u_long mtu)
  465 {
  466         struct hc_metrics *hc_entry;
  467 
  468         /*
  469          * Find the right bucket
  470          */
  471         hc_entry = tcp_hc_lookup(inc);
  472 
  473         /*
  474          * If we don't have an existing object try to insert a new one
  475          */
  476         if (hc_entry == NULL) {
  477                 hc_entry = tcp_hc_insert(inc);
  478                 if (hc_entry == NULL)
  479                         return;
  480         }
  481         hc_entry->rmx_updates++;
  482         hc_entry->rmx_expire = tcp_hostcache.expire; /* start over again */
  483 
  484         hc_entry->rmx_mtu = mtu;
  485 
  486         /*
  487          * put it upfront so we find it faster next time
  488          */
  489         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
  490         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
  491 
  492         /*
  493          * unlock bucket row
  494          */
  495         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
  496 }
  497 
  498 /*
  499  * External function: update the tcp metrics of an entry in the hostcache.
  500  * Creates a new entry if none was found.
  501  */
  502 void
  503 tcp_hc_update(struct in_conninfo *inc, struct hc_metrics_lite *hcml)
  504 {
  505         struct hc_metrics *hc_entry;
  506 
  507         hc_entry = tcp_hc_lookup(inc);
  508         if (hc_entry == NULL) {
  509                 hc_entry = tcp_hc_insert(inc);
  510                 if (hc_entry == NULL)
  511                         return;
  512         }
  513         hc_entry->rmx_updates++;
  514         hc_entry->rmx_expire = tcp_hostcache.expire; /* start over again */
  515 
  516         if (hcml->rmx_rtt != 0) {
  517                 if (hc_entry->rmx_rtt == 0)
  518                         hc_entry->rmx_rtt = hcml->rmx_rtt;
  519                 else
  520                         hc_entry->rmx_rtt =
  521                             (hc_entry->rmx_rtt + hcml->rmx_rtt) / 2;
  522                 tcpstat.tcps_cachedrtt++;
  523         }
  524         if (hcml->rmx_rttvar != 0) {
  525                 if (hc_entry->rmx_rttvar == 0)
  526                         hc_entry->rmx_rttvar = hcml->rmx_rttvar;
  527                 else
  528                         hc_entry->rmx_rttvar =
  529                             (hc_entry->rmx_rttvar + hcml->rmx_rttvar) / 2;
  530                 tcpstat.tcps_cachedrttvar++;
  531         }
  532         if (hcml->rmx_ssthresh != 0) {
  533                 if (hc_entry->rmx_ssthresh == 0)
  534                         hc_entry->rmx_ssthresh = hcml->rmx_ssthresh;
  535                 else
  536                         hc_entry->rmx_ssthresh =
  537                             (hc_entry->rmx_ssthresh + hcml->rmx_ssthresh) / 2;
  538                 tcpstat.tcps_cachedssthresh++;
  539         }
  540         if (hcml->rmx_bandwidth != 0) {
  541                 if (hc_entry->rmx_bandwidth == 0)
  542                         hc_entry->rmx_bandwidth = hcml->rmx_bandwidth;
  543                 else
  544                         hc_entry->rmx_bandwidth =
  545                             (hc_entry->rmx_bandwidth + hcml->rmx_bandwidth) / 2;
  546                 /* tcpstat.tcps_cachedbandwidth++; */
  547         }
  548         if (hcml->rmx_cwnd != 0) {
  549                 if (hc_entry->rmx_cwnd == 0)
  550                         hc_entry->rmx_cwnd = hcml->rmx_cwnd;
  551                 else
  552                         hc_entry->rmx_cwnd =
  553                             (hc_entry->rmx_cwnd + hcml->rmx_cwnd) / 2;
  554                 /* tcpstat.tcps_cachedcwnd++; */
  555         }
  556         if (hcml->rmx_sendpipe != 0) {
  557                 if (hc_entry->rmx_sendpipe == 0)
  558                         hc_entry->rmx_sendpipe = hcml->rmx_sendpipe;
  559                 else
  560                         hc_entry->rmx_sendpipe =
  561                             (hc_entry->rmx_sendpipe + hcml->rmx_sendpipe) /2;
  562                 /* tcpstat.tcps_cachedsendpipe++; */
  563         }
  564         if (hcml->rmx_recvpipe != 0) {
  565                 if (hc_entry->rmx_recvpipe == 0)
  566                         hc_entry->rmx_recvpipe = hcml->rmx_recvpipe;
  567                 else
  568                         hc_entry->rmx_recvpipe =
  569                             (hc_entry->rmx_recvpipe + hcml->rmx_recvpipe) /2;
  570                 /* tcpstat.tcps_cachedrecvpipe++; */
  571         }
  572 
  573         TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
  574         TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q);
  575         THC_UNLOCK(&hc_entry->rmx_head->hch_mtx);
  576 }
  577 
  578 /*
  579  * Sysctl function: prints the list and values of all hostcache entries in
  580  * unsorted order.
  581  */
  582 static int
  583 sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS)
  584 {
  585         int bufsize;
  586         int linesize = 128;
  587         char *p, *buf;
  588         int len, i, error;
  589         struct hc_metrics *hc_entry;
  590 
  591         bufsize = linesize * (tcp_hostcache.cache_count + 1);
  592 
  593         p = buf = (char *)malloc(bufsize, M_TEMP, M_WAITOK|M_ZERO);
  594 
  595         len = snprintf(p, linesize,
  596                 "\nIP address        MTU  SSTRESH      RTT   RTTVAR BANDWIDTH "
  597                 "    CWND SENDPIPE RECVPIPE HITS  UPD  EXP\n");
  598         p += len;
  599 
  600 #define msec(u) (((u) + 500) / 1000)
  601         for (i = 0; i < tcp_hostcache.hashsize; i++) {
  602                 THC_LOCK(&tcp_hostcache.hashbase[i].hch_mtx);
  603                 TAILQ_FOREACH(hc_entry, &tcp_hostcache.hashbase[i].hch_bucket,
  604                               rmx_q) {
  605                         len = snprintf(p, linesize,
  606                             "%-15s %5lu %8lu %6lums %6lums %9lu %8lu %8lu %8lu "
  607                             "%4lu %4lu %4i\n",
  608                             hc_entry->ip4.s_addr ? inet_ntoa(hc_entry->ip4) :
  609 #ifdef INET6
  610                                 ip6_sprintf(&hc_entry->ip6),
  611 #else
  612                                 "IPv6?",
  613 #endif
  614                             hc_entry->rmx_mtu,
  615                             hc_entry->rmx_ssthresh,
  616                             msec(hc_entry->rmx_rtt *
  617                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
  618                             msec(hc_entry->rmx_rttvar *
  619                                 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
  620                             hc_entry->rmx_bandwidth * 8,
  621                             hc_entry->rmx_cwnd,
  622                             hc_entry->rmx_sendpipe,
  623                             hc_entry->rmx_recvpipe,
  624                             hc_entry->rmx_hits,
  625                             hc_entry->rmx_updates,
  626                             hc_entry->rmx_expire);
  627                         p += len;
  628                 }
  629                 THC_UNLOCK(&tcp_hostcache.hashbase[i].hch_mtx);
  630         }
  631 #undef msec
  632         error = SYSCTL_OUT(req, buf, p - buf);
  633         free(buf, M_TEMP);
  634         return(error);
  635 }
  636 
  637 /*
  638  * Expire and purge (old|all) entries in the tcp_hostcache.  Runs periodically
  639  * from the callout.
  640  */
  641 static void
  642 tcp_hc_purge(void *arg)
  643 {
  644         struct hc_metrics *hc_entry, *hc_next;
  645         int all = (intptr_t)arg;
  646         int i;
  647 
  648         if (tcp_hostcache.purgeall) {
  649                 all = 1;
  650                 tcp_hostcache.purgeall = 0;
  651         }
  652 
  653         for (i = 0; i < tcp_hostcache.hashsize; i++) {
  654                 THC_LOCK(&tcp_hostcache.hashbase[i].hch_mtx);
  655                 TAILQ_FOREACH_SAFE(hc_entry, &tcp_hostcache.hashbase[i].hch_bucket,
  656                               rmx_q, hc_next) {
  657                         if (all || hc_entry->rmx_expire <= 0) {
  658                                 TAILQ_REMOVE(&tcp_hostcache.hashbase[i].hch_bucket,
  659                                               hc_entry, rmx_q);
  660                                 uma_zfree(tcp_hostcache.zone, hc_entry);
  661                                 tcp_hostcache.hashbase[i].hch_length--;
  662                                 tcp_hostcache.cache_count--;
  663                         } else
  664                                 hc_entry->rmx_expire -= TCP_HOSTCACHE_PRUNE;
  665                 }
  666                 THC_UNLOCK(&tcp_hostcache.hashbase[i].hch_mtx);
  667         }
  668         callout_reset(&tcp_hc_callout, TCP_HOSTCACHE_PRUNE * hz, tcp_hc_purge, 0);
  669 }

Cache object: d6508f8d7bf2b7d04c7643d80aad8313


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