Date: Fri, 14 Oct 2016 01:38:29 +0000 (UTC) From: Hiren Panchasara <hiren@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r307242 - stable/11/sys/netinet Message-ID: <201610140138.u9E1cTR5030089@repo.freebsd.org>
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Author: hiren Date: Fri Oct 14 01:38:29 2016 New Revision: 307242 URL: https://svnweb.freebsd.org/changeset/base/307242 Log: MFC r306464 This adds a sysctl which allows you to disable the TCP hostcache. This is handy during testing of network related changes where cached entries may pollute your results, or during known congestion events where you don't want to unfairly penalize hosts. Prior to r232346 this would have meant you would break any connection with a sub 1500 MTU, as the hostcache was authoritative. All entries as they stand today should simply be used to pre populate values for efficiency. Modified: stable/11/sys/netinet/tcp_hostcache.c Directory Properties: stable/11/ (props changed) Modified: stable/11/sys/netinet/tcp_hostcache.c ============================================================================== --- stable/11/sys/netinet/tcp_hostcache.c Fri Oct 14 01:23:21 2016 (r307241) +++ stable/11/sys/netinet/tcp_hostcache.c Fri Oct 14 01:38:29 2016 (r307242) @@ -124,6 +124,12 @@ static void tcp_hc_purge(void *); static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, hostcache, CTLFLAG_RW, 0, "TCP Host cache"); +VNET_DEFINE(int, tcp_use_hostcache) = 1; +#define V_tcp_use_hostcache VNET(tcp_use_hostcache) +SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, enable, CTLFLAG_VNET | CTLFLAG_RW, + &VNET_NAME(tcp_use_hostcache), 0, + "Enable the TCP hostcache"); + SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, cachelimit, CTLFLAG_VNET | CTLFLAG_RDTUN, &VNET_NAME(tcp_hostcache.cache_limit), 0, "Overall entry limit for hostcache"); @@ -276,6 +282,9 @@ tcp_hc_lookup(struct in_conninfo *inc) struct hc_head *hc_head; struct hc_metrics *hc_entry; + if (!V_tcp_use_hostcache) + return NULL; + KASSERT(inc != NULL, ("tcp_hc_lookup with NULL in_conninfo pointer")); /* @@ -332,6 +341,9 @@ tcp_hc_insert(struct in_conninfo *inc) struct hc_head *hc_head; struct hc_metrics *hc_entry; + if (!V_tcp_use_hostcache) + return NULL; + KASSERT(inc != NULL, ("tcp_hc_insert with NULL in_conninfo pointer")); /* @@ -421,6 +433,9 @@ tcp_hc_get(struct in_conninfo *inc, stru { struct hc_metrics *hc_entry; + if (!V_tcp_use_hostcache) + return; + /* * Find the right bucket. */ @@ -452,7 +467,7 @@ tcp_hc_get(struct in_conninfo *inc, stru /* * External function: look up an entry in the hostcache and return the - * discovered path MTU. Returns NULL if no entry is found or value is not + * discovered path MTU. Returns 0 if no entry is found or value is not * set. */ u_long @@ -461,6 +476,9 @@ tcp_hc_getmtu(struct in_conninfo *inc) struct hc_metrics *hc_entry; u_long mtu; + if (!V_tcp_use_hostcache) + return 0; + hc_entry = tcp_hc_lookup(inc); if (hc_entry == NULL) { return 0; @@ -482,6 +500,9 @@ tcp_hc_updatemtu(struct in_conninfo *inc { struct hc_metrics *hc_entry; + if (!V_tcp_use_hostcache) + return; + /* * Find the right bucket. */ @@ -521,6 +542,9 @@ tcp_hc_update(struct in_conninfo *inc, s { struct hc_metrics *hc_entry; + if (!V_tcp_use_hostcache) + return; + hc_entry = tcp_hc_lookup(inc); if (hc_entry == NULL) { hc_entry = tcp_hc_insert(inc);
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