Date: Wed, 9 Oct 2013 12:00:38 +0000 (UTC) From: Gleb Smirnoff <glebius@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r256186 - head/sys/netinet Message-ID: <201310091200.r99C0cLR039540@svn.freebsd.org>
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Author: glebius Date: Wed Oct 9 12:00:38 2013 New Revision: 256186 URL: http://svnweb.freebsd.org/changeset/base/256186 Log: When processing ACK in tcp_do_segment, use sbcut_locked() instead of sbdrop_locked() to cut acked mbufs from the socket buffer. Free this chain a batch manner after the socket buffer lock is dropped. This measurably reduces contention on socket buffer. Sponsored by: Netflix Sponsored by: Nginx, Inc. Approved by: re (marius) Modified: head/sys/netinet/tcp_input.c Modified: head/sys/netinet/tcp_input.c ============================================================================== --- head/sys/netinet/tcp_input.c Wed Oct 9 11:57:53 2013 (r256185) +++ head/sys/netinet/tcp_input.c Wed Oct 9 12:00:38 2013 (r256186) @@ -1461,6 +1461,7 @@ tcp_do_segment(struct mbuf *m, struct tc u_long tiwin; char *s; struct in_conninfo *inc; + struct mbuf *mfree; struct tcpopt to; #ifdef TCPDEBUG @@ -2718,15 +2719,17 @@ process_ACK: SOCKBUF_LOCK(&so->so_snd); if (acked > so->so_snd.sb_cc) { tp->snd_wnd -= so->so_snd.sb_cc; - sbdrop_locked(&so->so_snd, (int)so->so_snd.sb_cc); + mfree = sbcut_locked(&so->so_snd, + (int)so->so_snd.sb_cc); ourfinisacked = 1; } else { - sbdrop_locked(&so->so_snd, acked); + mfree = sbcut_locked(&so->so_snd, acked); tp->snd_wnd -= acked; ourfinisacked = 0; } /* NB: sowwakeup_locked() does an implicit unlock. */ sowwakeup_locked(so); + m_freem(mfree); /* Detect una wraparound. */ if (!IN_RECOVERY(tp->t_flags) && SEQ_GT(tp->snd_una, tp->snd_recover) &&
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