From bc7d18ae7224dbc67cf61fcdbceb6fc0976197b8 Mon Sep 17 00:00:00 2001 From: Alexander Motin Date: Mon, 9 May 2011 07:37:47 +0000 Subject: [PATCH] Refactor TCP ISN increment logic. Instead of firing callout at 100Hz to keep constant ISN growth rate, do the same directly inside tcp_new_isn(), taking into account how much time (ticks) passed since the last call. On my test systems this decreases idle interrupt rate from 140Hz to 70Hz. --- sys/netinet/tcp_subr.c | 45 +++++++++++------------------------------- 1 file changed, 11 insertions(+), 34 deletions(-) diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c index eafcb3dc315a..2c013bed8768 100644 --- a/sys/netinet/tcp_subr.c +++ b/sys/netinet/tcp_subr.c @@ -224,7 +224,6 @@ VNET_DEFINE(uma_zone_t, sack_hole_zone); VNET_DEFINE(struct hhook_head *, tcp_hhh[HHOOK_TCP_LAST+1]); static struct inpcb *tcp_notify(struct inpcb *, int); -static void tcp_isn_tick(void *); static char * tcp_log_addr(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr, const void *ip6hdr); @@ -255,7 +254,6 @@ static VNET_DEFINE(uma_zone_t, tcpcb_zone); #define V_tcpcb_zone VNET(tcpcb_zone) MALLOC_DEFINE(M_TCPLOG, "tcplog", "TCP address and flags print buffers"); -struct callout isn_callout; static struct mtx isn_mtx; #define ISN_LOCK_INIT() mtx_init(&isn_mtx, "isn_mtx", NULL, MTX_DEF) @@ -358,8 +356,6 @@ tcp_init(void) #undef TCP_MINPROTOHDR ISN_LOCK_INIT(); - callout_init(&isn_callout, CALLOUT_MPSAFE); - callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL); EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL, SHUTDOWN_PRI_DEFAULT); EVENTHANDLER_REGISTER(maxsockets_change, tcp_zone_change, NULL, @@ -385,7 +381,6 @@ void tcp_fini(void *xtp) { - callout_stop(&isn_callout); } /* @@ -1571,11 +1566,13 @@ tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d) #define ISN_RANDOM_INCREMENT (4096 - 1) static VNET_DEFINE(u_char, isn_secret[32]); +static VNET_DEFINE(int, isn_last); static VNET_DEFINE(int, isn_last_reseed); static VNET_DEFINE(u_int32_t, isn_offset); static VNET_DEFINE(u_int32_t, isn_offset_old); #define V_isn_secret VNET(isn_secret) +#define V_isn_last VNET(isn_last) #define V_isn_last_reseed VNET(isn_last_reseed) #define V_isn_offset VNET(isn_offset) #define V_isn_offset_old VNET(isn_offset_old) @@ -1586,6 +1583,7 @@ tcp_new_isn(struct tcpcb *tp) MD5_CTX isn_ctx; u_int32_t md5_buffer[4]; tcp_seq new_isn; + u_int32_t projected_offset; INP_WLOCK_ASSERT(tp->t_inpcb); @@ -1621,40 +1619,19 @@ tcp_new_isn(struct tcpcb *tp) new_isn = (tcp_seq) md5_buffer[0]; V_isn_offset += ISN_STATIC_INCREMENT + (arc4random() & ISN_RANDOM_INCREMENT); + if (ticks != V_isn_last) { + projected_offset = V_isn_offset_old + + ISN_BYTES_PER_SECOND / hz * (ticks - V_isn_last); + if (SEQ_GT(projected_offset, V_isn_offset)) + V_isn_offset = projected_offset; + V_isn_offset_old = V_isn_offset; + V_isn_last = ticks; + } new_isn += V_isn_offset; ISN_UNLOCK(); return (new_isn); } -/* - * Increment the offset to the next ISN_BYTES_PER_SECOND / 100 boundary - * to keep time flowing at a relatively constant rate. If the random - * increments have already pushed us past the projected offset, do nothing. - */ -static void -tcp_isn_tick(void *xtp) -{ - VNET_ITERATOR_DECL(vnet_iter); - u_int32_t projected_offset; - - VNET_LIST_RLOCK_NOSLEEP(); - ISN_LOCK(); - VNET_FOREACH(vnet_iter) { - CURVNET_SET(vnet_iter); /* XXX appease INVARIANTS */ - projected_offset = - V_isn_offset_old + ISN_BYTES_PER_SECOND / 100; - - if (SEQ_GT(projected_offset, V_isn_offset)) - V_isn_offset = projected_offset; - - V_isn_offset_old = V_isn_offset; - CURVNET_RESTORE(); - } - ISN_UNLOCK(); - VNET_LIST_RUNLOCK_NOSLEEP(); - callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL); -} - /* * When a specific ICMP unreachable message is received and the * connection state is SYN-SENT, drop the connection. This behavior