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tcp_hostcache: use SMR for lookups, mutex(9) for updates.

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In certain cases, e.g. a SYN-flood from a limited set of hosts,
the TCP hostcache becomes the main contention point. To solve
that, this change introduces lockless lookups on the hostcache.

The cache remains a hash, however buckets are now CK_SLIST. For
updates a bucket mutex is obtained, for read an SMR section is
entered.

Reviewed by:	markj, rscheff
Differential revision:	https://reviews.freebsd.org/D29729
This commit is contained in:
Gleb Smirnoff 2021-03-22 15:32:57 -07:00
parent 1db08fbe3f
commit d554522f6e
1 changed files with 238 additions and 235 deletions
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473
sys/netinet/tcp_hostcache.c
View File

@ -2,6 +2,7 @@
* SPDX-License-Identifier: BSD-3-Clause * SPDX-License-Identifier: BSD-3-Clause
* *
* Copyright (c) 2002 Andre Oppermann, Internet Business Solutions AG * Copyright (c) 2002 Andre Oppermann, Internet Business Solutions AG
* Copyright (c) 2021 Gleb Smirnoff <glebius@FreeBSD.org>
* All rights reserved. * All rights reserved.
* *
* Redistribution and use in source and binary forms, with or without * Redistribution and use in source and binary forms, with or without
@ -45,18 +46,18 @@
* more lightwight and only carries information related to packet forwarding. * more lightwight and only carries information related to packet forwarding.
* *
* tcp_hostcache is designed for multiple concurrent access in SMP * tcp_hostcache is designed for multiple concurrent access in SMP
* environments and high contention. All bucket rows have their own lock and * environments and high contention. It is a straight hash. Each bucket row
* thus multiple lookups and modifies can be done at the same time as long as * is protected by its own lock for modification. Readers are protected by
* they are in different bucket rows. If a request for insertion of a new * SMR. This puts certain restrictions on writers, e.g. a writer shall only
* record can't be satisfied, it simply returns an empty structure. Nobody * insert a fully populated entry into a row. Writer can't reuse least used
* and nothing outside of tcp_hostcache.c will ever point directly to any * entry if a hash is full. Value updates for an entry shall be atomic.
* entry in the tcp_hostcache. All communication is done in an *
* object-oriented way and only functions of tcp_hostcache will manipulate * TCP stack(s) communication with tcp_hostcache() is done via KBI functions
* hostcache entries. Otherwise, we are unable to achieve good behaviour in * tcp_hc_*() and the hc_metrics_lite structure.
* concurrent access situations. Since tcp_hostcache is only caching *
* information, there are no fatal consequences if we either can't satisfy * Since tcp_hostcache is only caching information, there are no fatal
* any particular request or have to drop/overwrite an existing entry because * consequences if we either can't allocate a new entry or have to drop
* of bucket limit memory constrains. * an existing entry, or return somewhat stale information.
*/ */
/* /*
@ -79,6 +80,7 @@ __FBSDID("$FreeBSD$");
#include <sys/malloc.h> #include <sys/malloc.h>
#include <sys/proc.h> #include <sys/proc.h>
#include <sys/sbuf.h> #include <sys/sbuf.h>
#include <sys/smr.h>
#include <sys/socket.h> #include <sys/socket.h>
#include <sys/socketvar.h> #include <sys/socketvar.h>
#include <sys/sysctl.h> #include <sys/sysctl.h>
@ -92,18 +94,15 @@ __FBSDID("$FreeBSD$");
#include <vm/uma.h> #include <vm/uma.h>
TAILQ_HEAD(hc_qhead, hc_metrics);
struct hc_head { struct hc_head {
struct hc_qhead hch_bucket; CK_SLIST_HEAD(hc_qhead, hc_metrics) hch_bucket;
u_int hch_length; u_int hch_length;
struct mtx hch_mtx; struct mtx hch_mtx;
}; };
struct hc_metrics { struct hc_metrics {
/* housekeeping */ /* housekeeping */
TAILQ_ENTRY(hc_metrics) rmx_q; CK_SLIST_ENTRY(hc_metrics) rmx_q;
struct hc_head *rmx_head; /* head of bucket tail queue */
struct in_addr ip4; /* IP address */ struct in_addr ip4; /* IP address */
struct in6_addr ip6; /* IP6 address */ struct in6_addr ip6; /* IP6 address */
uint32_t ip6_zoneid; /* IPv6 scope zone id */ uint32_t ip6_zoneid; /* IPv6 scope zone id */
@ -126,6 +125,7 @@ struct hc_metrics {
struct tcp_hostcache { struct tcp_hostcache {
struct hc_head *hashbase; struct hc_head *hashbase;
uma_zone_t zone; uma_zone_t zone;
smr_t smr;
u_int hashsize; u_int hashsize;
u_int hashmask; u_int hashmask;
u_int hashsalt; u_int hashsalt;
@ -149,8 +149,7 @@ VNET_DEFINE_STATIC(struct tcp_hostcache, tcp_hostcache);
VNET_DEFINE_STATIC(struct callout, tcp_hc_callout); VNET_DEFINE_STATIC(struct callout, tcp_hc_callout);
#define V_tcp_hc_callout VNET(tcp_hc_callout) #define V_tcp_hc_callout VNET(tcp_hc_callout)
static struct hc_metrics *tcp_hc_lookup(struct in_conninfo *, bool); static struct hc_metrics *tcp_hc_lookup(struct in_conninfo *);
static struct hc_metrics *tcp_hc_insert(struct in_conninfo *);
static int sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS); static int sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS);
static int sysctl_tcp_hc_histo(SYSCTL_HANDLER_ARGS); static int sysctl_tcp_hc_histo(SYSCTL_HANDLER_ARGS);
static int sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS); static int sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS);
@ -213,14 +212,13 @@ SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, purgenow,
static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache"); static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache");
/* Use jenkins_hash32(), as in other parts of the tcp stack */ /* Use jenkins_hash32(), as in other parts of the tcp stack */
#define HOSTCACHE_HASH(ip) \ #define HOSTCACHE_HASH(inc) \
(jenkins_hash32((uint32_t *)(ip), 1, V_tcp_hostcache.hashsalt) & \ ((inc)->inc_flags & INC_ISIPV6) ? \
V_tcp_hostcache.hashmask) (jenkins_hash32((inc)->inc6_faddr.s6_addr32, 4, \
V_tcp_hostcache.hashsalt) & V_tcp_hostcache.hashmask) \
#define HOSTCACHE_HASH6(ip6) \ : \
(jenkins_hash32((uint32_t *)&((ip6)->s6_addr32[0]), 4, \ (jenkins_hash32(&(inc)->inc_faddr.s_addr, 1, \
V_tcp_hostcache.hashsalt) & \ V_tcp_hostcache.hashsalt) & V_tcp_hostcache.hashmask)
V_tcp_hostcache.hashmask)
#define THC_LOCK(h) mtx_lock(&(h)->hch_mtx) #define THC_LOCK(h) mtx_lock(&(h)->hch_mtx)
#define THC_UNLOCK(h) mtx_unlock(&(h)->hch_mtx) #define THC_UNLOCK(h) mtx_unlock(&(h)->hch_mtx)
@ -270,7 +268,7 @@ tcp_hc_init(void)
* Initialize the hash buckets. * Initialize the hash buckets.
*/ */
for (i = 0; i < V_tcp_hostcache.hashsize; i++) { for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
TAILQ_INIT(&V_tcp_hostcache.hashbase[i].hch_bucket); CK_SLIST_INIT(&V_tcp_hostcache.hashbase[i].hch_bucket);
V_tcp_hostcache.hashbase[i].hch_length = 0; V_tcp_hostcache.hashbase[i].hch_length = 0;
mtx_init(&V_tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry", mtx_init(&V_tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry",
NULL, MTX_DEF); NULL, MTX_DEF);
@ -281,8 +279,9 @@ tcp_hc_init(void)
*/ */
V_tcp_hostcache.zone = V_tcp_hostcache.zone =
uma_zcreate("hostcache", sizeof(struct hc_metrics), uma_zcreate("hostcache", sizeof(struct hc_metrics),
NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_SMR);
uma_zone_set_max(V_tcp_hostcache.zone, V_tcp_hostcache.cache_limit); uma_zone_set_max(V_tcp_hostcache.zone, V_tcp_hostcache.cache_limit);
V_tcp_hostcache.smr = uma_zone_get_smr(V_tcp_hostcache.zone);
/* /*
* Set up periodic cache cleanup. * Set up periodic cache cleanup.
@ -313,169 +312,58 @@ tcp_hc_destroy(void)
#endif #endif
/* /*
* Internal function: look up an entry in the hostcache or return NULL. * Internal function: compare cache entry to a connection.
* */
* If an entry has been returned, the caller becomes responsible for static bool
* unlocking the bucket row after he is done reading/modifying the entry. tcp_hc_cmp(struct hc_metrics *hc_entry, struct in_conninfo *inc)
{
if (inc->inc_flags & INC_ISIPV6) {
/* XXX: check ip6_zoneid */
if (memcmp(&inc->inc6_faddr, &hc_entry->ip6,
sizeof(inc->inc6_faddr)) == 0)
return (true);
} else {
if (memcmp(&inc->inc_faddr, &hc_entry->ip4,
sizeof(inc->inc_faddr)) == 0)
return (true);
}
return (false);
}
/*
* Internal function: look up an entry in the hostcache for read.
* On success returns in SMR section.
*/ */
static struct hc_metrics * static struct hc_metrics *
tcp_hc_lookup(struct in_conninfo *inc, bool update) tcp_hc_lookup(struct in_conninfo *inc)
{ {
int hash;
struct hc_head *hc_head; struct hc_head *hc_head;
struct hc_metrics *hc_entry; struct hc_metrics *hc_entry;
KASSERT(inc != NULL, ("%s: NULL in_conninfo", __func__)); KASSERT(inc != NULL, ("%s: NULL in_conninfo", __func__));
/* hc_head = &V_tcp_hostcache.hashbase[HOSTCACHE_HASH(inc)];
* Hash the foreign ip address.
*/
if (inc->inc_flags & INC_ISIPV6)
hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
else
hash = HOSTCACHE_HASH(&inc->inc_faddr);
hc_head = &V_tcp_hostcache.hashbase[hash];
/*
* Acquire lock for this bucket row; we release the lock if we don't
* find an entry, otherwise the caller has to unlock after he is
* done.
*/
THC_LOCK(hc_head);
/* /*
* Iterate through entries in bucket row looking for a match. * Iterate through entries in bucket row looking for a match.
*/ */
TAILQ_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q) { smr_enter(V_tcp_hostcache.smr);
if (inc->inc_flags & INC_ISIPV6) { CK_SLIST_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q)
/* XXX: check ip6_zoneid */ if (tcp_hc_cmp(hc_entry, inc))
if (memcmp(&inc->inc6_faddr, &hc_entry->ip6, break;
sizeof(inc->inc6_faddr)) == 0)
goto found;
} else {
if (memcmp(&inc->inc_faddr, &hc_entry->ip4,
sizeof(inc->inc_faddr)) == 0)
goto found;
}
}
/* if (hc_entry != NULL) {
* We were unsuccessful and didn't find anything. if (atomic_load_int(&hc_entry->rmx_expire) !=
*/ V_tcp_hostcache.expire)
THC_UNLOCK(hc_head); atomic_store_int(&hc_entry->rmx_expire,
return (NULL); V_tcp_hostcache.expire);
found:
#ifdef TCP_HC_COUNTERS #ifdef TCP_HC_COUNTERS
if (update)
hc_entry->rmx_updates++;
else
hc_entry->rmx_hits++; hc_entry->rmx_hits++;
#endif #endif
hc_entry->rmx_expire = V_tcp_hostcache.expire;
return (hc_entry);
}
/*
* Internal function: insert an entry into the hostcache or return NULL if
* unable to allocate a new one.
*
* If an entry has been returned, the caller becomes responsible for
* unlocking the bucket row after he is done reading/modifying the entry.
*/
static struct hc_metrics *
tcp_hc_insert(struct in_conninfo *inc)
{
int hash;
struct hc_head *hc_head;
struct hc_metrics *hc_entry;
KASSERT(inc != NULL, ("%s: NULL in_conninfo", __func__));
/*
* Hash the foreign ip address.
*/
if (inc->inc_flags & INC_ISIPV6)
hash = HOSTCACHE_HASH6(&inc->inc6_faddr);
else
hash = HOSTCACHE_HASH(&inc->inc_faddr);
hc_head = &V_tcp_hostcache.hashbase[hash];
/*
* Acquire lock for this bucket row; we release the lock if we don't
* find an entry, otherwise the caller has to unlock after he is
* done.
*/
THC_LOCK(hc_head);
/*
* If the bucket limit is reached, reuse the least-used element.
*/
if (hc_head->hch_length >= V_tcp_hostcache.bucket_limit ||
atomic_load_int(&V_tcp_hostcache.cache_count) >= V_tcp_hostcache.cache_limit) {
hc_entry = TAILQ_LAST(&hc_head->hch_bucket, hc_qhead);
/*
* At first we were dropping the last element, just to
* reacquire it in the next two lines again, which isn't very
* efficient. Instead just reuse the least used element.
* We may drop something that is still "in-use" but we can be
* "lossy".
* Just give up if this bucket row is empty and we don't have
* anything to replace.
*/
if (hc_entry == NULL) {
THC_UNLOCK(hc_head);
return (NULL);
}
TAILQ_REMOVE(&hc_head->hch_bucket, hc_entry, rmx_q);
KASSERT(V_tcp_hostcache.hashbase[hash].hch_length > 0 &&
V_tcp_hostcache.hashbase[hash].hch_length <=
V_tcp_hostcache.bucket_limit,
("tcp_hostcache: bucket length range violated at %u: %u",
hash, V_tcp_hostcache.hashbase[hash].hch_length));
V_tcp_hostcache.hashbase[hash].hch_length--;
atomic_subtract_int(&V_tcp_hostcache.cache_count, 1);
TCPSTAT_INC(tcps_hc_bucketoverflow);
#if 0
uma_zfree(V_tcp_hostcache.zone, hc_entry);
#endif
} else {
/*
* Allocate a new entry, or balk if not possible.
*/
hc_entry = uma_zalloc(V_tcp_hostcache.zone, M_NOWAIT);
if (hc_entry == NULL) {
THC_UNLOCK(hc_head);
return (NULL);
}
}
/*
* Initialize basic information of hostcache entry.
*/
bzero(hc_entry, sizeof(*hc_entry));
if (inc->inc_flags & INC_ISIPV6) {
hc_entry->ip6 = inc->inc6_faddr;
hc_entry->ip6_zoneid = inc->inc6_zoneid;
} else } else
hc_entry->ip4 = inc->inc_faddr; smr_exit(V_tcp_hostcache.smr);
hc_entry->rmx_head = hc_head;
hc_entry->rmx_expire = V_tcp_hostcache.expire;
/*
* Put it upfront.
*/
TAILQ_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
V_tcp_hostcache.hashbase[hash].hch_length++;
KASSERT(V_tcp_hostcache.hashbase[hash].hch_length <=
V_tcp_hostcache.bucket_limit,
("tcp_hostcache: bucket length too high at %u: %u",
hash, V_tcp_hostcache.hashbase[hash].hch_length));
atomic_add_int(&V_tcp_hostcache.cache_count, 1);
TCPSTAT_INC(tcps_hc_added);
return (hc_entry); return (hc_entry);
} }
@ -498,7 +386,7 @@ tcp_hc_get(struct in_conninfo *inc, struct hc_metrics_lite *hc_metrics_lite)
/* /*
* Find the right bucket. * Find the right bucket.
*/ */
hc_entry = tcp_hc_lookup(inc, false); hc_entry = tcp_hc_lookup(inc);
/* /*
* If we don't have an existing object. * If we don't have an existing object.
@ -508,18 +396,15 @@ tcp_hc_get(struct in_conninfo *inc, struct hc_metrics_lite *hc_metrics_lite)
return; return;
} }
hc_metrics_lite->rmx_mtu = hc_entry->rmx_mtu; hc_metrics_lite->rmx_mtu = atomic_load_32(&hc_entry->rmx_mtu);
hc_metrics_lite->rmx_ssthresh = hc_entry->rmx_ssthresh; hc_metrics_lite->rmx_ssthresh = atomic_load_32(&hc_entry->rmx_ssthresh);
hc_metrics_lite->rmx_rtt = hc_entry->rmx_rtt; hc_metrics_lite->rmx_rtt = atomic_load_32(&hc_entry->rmx_rtt);
hc_metrics_lite->rmx_rttvar = hc_entry->rmx_rttvar; hc_metrics_lite->rmx_rttvar = atomic_load_32(&hc_entry->rmx_rttvar);
hc_metrics_lite->rmx_cwnd = hc_entry->rmx_cwnd; hc_metrics_lite->rmx_cwnd = atomic_load_32(&hc_entry->rmx_cwnd);
hc_metrics_lite->rmx_sendpipe = hc_entry->rmx_sendpipe; hc_metrics_lite->rmx_sendpipe = atomic_load_32(&hc_entry->rmx_sendpipe);
hc_metrics_lite->rmx_recvpipe = hc_entry->rmx_recvpipe; hc_metrics_lite->rmx_recvpipe = atomic_load_32(&hc_entry->rmx_recvpipe);
/* smr_exit(V_tcp_hostcache.smr);
* Unlock bucket row.
*/
THC_UNLOCK(hc_entry->rmx_head);
} }
/* /*
@ -536,13 +421,14 @@ tcp_hc_getmtu(struct in_conninfo *inc)
if (!V_tcp_use_hostcache) if (!V_tcp_use_hostcache)
return (0); return (0);
hc_entry = tcp_hc_lookup(inc, false); hc_entry = tcp_hc_lookup(inc);
if (hc_entry == NULL) { if (hc_entry == NULL) {
return (0); return (0);
} }
mtu = hc_entry->rmx_mtu; mtu = atomic_load_32(&hc_entry->rmx_mtu);
THC_UNLOCK(hc_entry->rmx_head); smr_exit(V_tcp_hostcache.smr);
return (mtu); return (mtu);
} }
@ -565,75 +451,175 @@ tcp_hc_updatemtu(struct in_conninfo *inc, uint32_t mtu)
void void
tcp_hc_update(struct in_conninfo *inc, struct hc_metrics_lite *hcml) tcp_hc_update(struct in_conninfo *inc, struct hc_metrics_lite *hcml)
{ {
struct hc_metrics *hc_entry; struct hc_head *hc_head;
struct hc_metrics *hc_entry, *hc_prev;
uint32_t v;
bool new;
if (!V_tcp_use_hostcache) if (!V_tcp_use_hostcache)
return; return;
hc_entry = tcp_hc_lookup(inc, true); hc_head = &V_tcp_hostcache.hashbase[HOSTCACHE_HASH(inc)];
if (hc_entry == NULL) { hc_prev = NULL;
hc_entry = tcp_hc_insert(inc);
if (hc_entry == NULL) THC_LOCK(hc_head);
return; CK_SLIST_FOREACH(hc_entry, &hc_head->hch_bucket, rmx_q) {
if (tcp_hc_cmp(hc_entry, inc))
break;
if (CK_SLIST_NEXT(hc_entry, rmx_q) != NULL)
hc_prev = hc_entry;
} }
if (hc_entry != NULL) {
if (atomic_load_int(&hc_entry->rmx_expire) !=
V_tcp_hostcache.expire)
atomic_store_int(&hc_entry->rmx_expire,
V_tcp_hostcache.expire);
#ifdef TCP_HC_COUNTERS
hc_entry->rmx_updates++;
#endif
new = false;
} else {
/*
* Try to allocate a new entry. If the bucket limit is
* reached, delete the least-used element, located at the end
* of the CK_SLIST. During lookup we saved the pointer to
* the second to last element, in case if list has at least 2
* elements. This will allow to delete last element without
* extra traversal.
*
* Give up if the row is empty.
*/
if (hc_head->hch_length >= V_tcp_hostcache.bucket_limit ||
atomic_load_int(&V_tcp_hostcache.cache_count) >=
V_tcp_hostcache.cache_limit) {
if (hc_prev != NULL) {
hc_entry = CK_SLIST_NEXT(hc_prev, rmx_q);
KASSERT(CK_SLIST_NEXT(hc_entry, rmx_q) == NULL,
("%s: %p is not one to last",
__func__, hc_prev));
CK_SLIST_REMOVE_AFTER(hc_prev, rmx_q);
} else if ((hc_entry =
CK_SLIST_FIRST(&hc_head->hch_bucket)) != NULL) {
KASSERT(CK_SLIST_NEXT(hc_entry, rmx_q) == NULL,
("%s: %p is not the only element",
__func__, hc_entry));
CK_SLIST_REMOVE_HEAD(&hc_head->hch_bucket,
rmx_q);
} else {
THC_UNLOCK(hc_head);
return;
}
KASSERT(hc_head->hch_length > 0 &&
hc_head->hch_length <= V_tcp_hostcache.bucket_limit,
("tcp_hostcache: bucket length violated at %p",
hc_head));
hc_head->hch_length--;
atomic_subtract_int(&V_tcp_hostcache.cache_count, 1);
TCPSTAT_INC(tcps_hc_bucketoverflow);
uma_zfree_smr(V_tcp_hostcache.zone, hc_entry);
}
/*
* Allocate a new entry, or balk if not possible.
*/
hc_entry = uma_zalloc_smr(V_tcp_hostcache.zone, M_NOWAIT);
if (hc_entry == NULL) {
THC_UNLOCK(hc_head);
return;
}
/*
* Initialize basic information of hostcache entry.
*/
bzero(hc_entry, sizeof(*hc_entry));
if (inc->inc_flags & INC_ISIPV6) {
hc_entry->ip6 = inc->inc6_faddr;
hc_entry->ip6_zoneid = inc->inc6_zoneid;
} else
hc_entry->ip4 = inc->inc_faddr;
hc_entry->rmx_expire = V_tcp_hostcache.expire;
new = true;
}
/*
* Fill in data. Use atomics, since an existing entry is
* accessible by readers in SMR section.
*/
if (hcml->rmx_mtu != 0) { if (hcml->rmx_mtu != 0) {
hc_entry->rmx_mtu = hcml->rmx_mtu; atomic_store_32(&hc_entry->rmx_mtu, hcml->rmx_mtu);
} }
if (hcml->rmx_rtt != 0) { if (hcml->rmx_rtt != 0) {
if (hc_entry->rmx_rtt == 0) if (hc_entry->rmx_rtt == 0)
hc_entry->rmx_rtt = hcml->rmx_rtt; v = hcml->rmx_rtt;
else else
hc_entry->rmx_rtt = ((uint64_t)hc_entry->rmx_rtt + v = ((uint64_t)hc_entry->rmx_rtt +
(uint64_t)hcml->rmx_rtt) / 2; (uint64_t)hcml->rmx_rtt) / 2;
atomic_store_32(&hc_entry->rmx_rtt, v);
TCPSTAT_INC(tcps_cachedrtt); TCPSTAT_INC(tcps_cachedrtt);
} }
if (hcml->rmx_rttvar != 0) { if (hcml->rmx_rttvar != 0) {
if (hc_entry->rmx_rttvar == 0) if (hc_entry->rmx_rttvar == 0)
hc_entry->rmx_rttvar = hcml->rmx_rttvar; v = hcml->rmx_rttvar;
else else
hc_entry->rmx_rttvar = ((uint64_t)hc_entry->rmx_rttvar + v = ((uint64_t)hc_entry->rmx_rttvar +
(uint64_t)hcml->rmx_rttvar) / 2; (uint64_t)hcml->rmx_rttvar) / 2;
atomic_store_32(&hc_entry->rmx_rttvar, v);
TCPSTAT_INC(tcps_cachedrttvar); TCPSTAT_INC(tcps_cachedrttvar);
} }
if (hcml->rmx_ssthresh != 0) { if (hcml->rmx_ssthresh != 0) {
if (hc_entry->rmx_ssthresh == 0) if (hc_entry->rmx_ssthresh == 0)
hc_entry->rmx_ssthresh = hcml->rmx_ssthresh; v = hcml->rmx_ssthresh;
else else
hc_entry->rmx_ssthresh = v = (hc_entry->rmx_ssthresh + hcml->rmx_ssthresh) / 2;
(hc_entry->rmx_ssthresh + hcml->rmx_ssthresh) / 2; atomic_store_32(&hc_entry->rmx_ssthresh, v);
TCPSTAT_INC(tcps_cachedssthresh); TCPSTAT_INC(tcps_cachedssthresh);
} }
if (hcml->rmx_cwnd != 0) { if (hcml->rmx_cwnd != 0) {
if (hc_entry->rmx_cwnd == 0) if (hc_entry->rmx_cwnd == 0)
hc_entry->rmx_cwnd = hcml->rmx_cwnd; v = hcml->rmx_cwnd;
else else
hc_entry->rmx_cwnd = ((uint64_t)hc_entry->rmx_cwnd + v = ((uint64_t)hc_entry->rmx_cwnd +
(uint64_t)hcml->rmx_cwnd) / 2; (uint64_t)hcml->rmx_cwnd) / 2;
atomic_store_32(&hc_entry->rmx_cwnd, v);
/* TCPSTAT_INC(tcps_cachedcwnd); */ /* TCPSTAT_INC(tcps_cachedcwnd); */
} }
if (hcml->rmx_sendpipe != 0) { if (hcml->rmx_sendpipe != 0) {
if (hc_entry->rmx_sendpipe == 0) if (hc_entry->rmx_sendpipe == 0)
hc_entry->rmx_sendpipe = hcml->rmx_sendpipe; v = hcml->rmx_sendpipe;
else else
hc_entry->rmx_sendpipe = v = ((uint64_t)hc_entry->rmx_sendpipe +
((uint64_t)hc_entry->rmx_sendpipe +
(uint64_t)hcml->rmx_sendpipe) /2; (uint64_t)hcml->rmx_sendpipe) /2;
atomic_store_32(&hc_entry->rmx_sendpipe, v);
/* TCPSTAT_INC(tcps_cachedsendpipe); */ /* TCPSTAT_INC(tcps_cachedsendpipe); */
} }
if (hcml->rmx_recvpipe != 0) { if (hcml->rmx_recvpipe != 0) {
if (hc_entry->rmx_recvpipe == 0) if (hc_entry->rmx_recvpipe == 0)
hc_entry->rmx_recvpipe = hcml->rmx_recvpipe; v = hcml->rmx_recvpipe;
else else
hc_entry->rmx_recvpipe = v = ((uint64_t)hc_entry->rmx_recvpipe +
((uint64_t)hc_entry->rmx_recvpipe +
(uint64_t)hcml->rmx_recvpipe) /2; (uint64_t)hcml->rmx_recvpipe) /2;
atomic_store_32(&hc_entry->rmx_recvpipe, v);
/* TCPSTAT_INC(tcps_cachedrecvpipe); */ /* TCPSTAT_INC(tcps_cachedrecvpipe); */
} }
TAILQ_REMOVE(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q); /*
TAILQ_INSERT_HEAD(&hc_entry->rmx_head->hch_bucket, hc_entry, rmx_q); * Put it upfront.
THC_UNLOCK(hc_entry->rmx_head); */
if (new) {
CK_SLIST_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
hc_head->hch_length++;
KASSERT(hc_head->hch_length <= V_tcp_hostcache.bucket_limit,
("tcp_hostcache: bucket length too high at %p", hc_head));
atomic_add_int(&V_tcp_hostcache.cache_count, 1);
TCPSTAT_INC(tcps_hc_added);
} else if (hc_entry != CK_SLIST_FIRST(&hc_head->hch_bucket)) {
KASSERT(CK_SLIST_NEXT(hc_prev, rmx_q) == hc_entry,
("%s: %p next is not %p", __func__, hc_prev, hc_entry));
CK_SLIST_REMOVE_AFTER(hc_prev, rmx_q);
CK_SLIST_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, rmx_q);
}
THC_UNLOCK(hc_head);
} }
/* /*
@ -683,8 +669,8 @@ sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS)
#define msec(u) (((u) + 500) / 1000) #define msec(u) (((u) + 500) / 1000)
for (i = 0; i < V_tcp_hostcache.hashsize; i++) { for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
THC_LOCK(&V_tcp_hostcache.hashbase[i]); THC_LOCK(&V_tcp_hostcache.hashbase[i]);
TAILQ_FOREACH(hc_entry, &V_tcp_hostcache.hashbase[i].hch_bucket, CK_SLIST_FOREACH(hc_entry,
rmx_q) { &V_tcp_hostcache.hashbase[i].hch_bucket, rmx_q) {
sbuf_printf(&sb, sbuf_printf(&sb,
"%-15s %5u %8u %6lums %6lums %8u %8u %8u " "%-15s %5u %8u %6lums %6lums %8u %8u %8u "
#ifdef TCP_HC_COUNTERS #ifdef TCP_HC_COUNTERS
@ -770,29 +756,46 @@ sysctl_tcp_hc_histo(SYSCTL_HANDLER_ARGS)
static void static void
tcp_hc_purge_internal(int all) tcp_hc_purge_internal(int all)
{ {
struct hc_metrics *hc_entry, *hc_next; struct hc_head *head;
struct hc_metrics *hc_entry, *hc_next, *hc_prev;
int i; int i;
for (i = 0; i < V_tcp_hostcache.hashsize; i++) { for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
THC_LOCK(&V_tcp_hostcache.hashbase[i]); head = &V_tcp_hostcache.hashbase[i];
TAILQ_FOREACH_SAFE(hc_entry, hc_prev = NULL;
&V_tcp_hostcache.hashbase[i].hch_bucket, rmx_q, hc_next) { THC_LOCK(head);
KASSERT(V_tcp_hostcache.hashbase[i].hch_length > 0 && CK_SLIST_FOREACH_SAFE(hc_entry, &head->hch_bucket, rmx_q,
V_tcp_hostcache.hashbase[i].hch_length <= hc_next) {
KASSERT(head->hch_length > 0 && head->hch_length <=
V_tcp_hostcache.bucket_limit, ("tcp_hostcache: " V_tcp_hostcache.bucket_limit, ("tcp_hostcache: "
"bucket length out of range at %u: %u", "bucket length out of range at %u: %u", i,
i, V_tcp_hostcache.hashbase[i].hch_length)); head->hch_length));
if (all || hc_entry->rmx_expire <= 0) { if (all ||
TAILQ_REMOVE( atomic_load_int(&hc_entry->rmx_expire) <= 0) {
&V_tcp_hostcache.hashbase[i].hch_bucket, if (hc_prev != NULL) {
hc_entry, rmx_q); KASSERT(hc_entry ==
uma_zfree(V_tcp_hostcache.zone, hc_entry); CK_SLIST_NEXT(hc_prev, rmx_q),
V_tcp_hostcache.hashbase[i].hch_length--; ("%s: %p is not next to %p",
__func__, hc_entry, hc_prev));
CK_SLIST_REMOVE_AFTER(hc_prev, rmx_q);
} else {
KASSERT(hc_entry ==
CK_SLIST_FIRST(&head->hch_bucket),
("%s: %p is not first",
__func__, hc_entry));
CK_SLIST_REMOVE_HEAD(&head->hch_bucket,
rmx_q);
}
uma_zfree_smr(V_tcp_hostcache.zone, hc_entry);
head->hch_length--;
atomic_subtract_int(&V_tcp_hostcache.cache_count, 1); atomic_subtract_int(&V_tcp_hostcache.cache_count, 1);
} else } else {
hc_entry->rmx_expire -= V_tcp_hostcache.prune; atomic_subtract_int(&hc_entry->rmx_expire,
V_tcp_hostcache.prune);
hc_prev = hc_entry;
}
} }
THC_UNLOCK(&V_tcp_hostcache.hashbase[i]); THC_UNLOCK(head);
} }
} }