git: tcp: Aggregate the mbuf in sosendtcp() a little bit

[Sepherosa Ziehau]

commit c16aca65782c69370a255842c2e43ad127e5249d
Author: Sepherosa Ziehau <sephe at dragonflybsd.org>
Date:   Mon Oct 24 19:21:37 2011 +0800

    tcp: Aggregate the mbuf in sosendtcp() a little bit
    
    This greatly reducse the ipi interrupts caused by ipi sending (both
    domsg and sendmsg), thus improves overall performance a bit.
    
    net.inet.tcp.sosnd_agglim is added to tune how much mbuf should be
    aggregated; it is default to 2.  Setting this sysctl to 1 restores
    the old behaviour: one full mbuf at a time.
    
    On Phenom 9550 (4 core, 2.2GHz):
    8 parallel netperf -H 127.0.0.1 -P0 (4 runs, unit; Mbps)
    
                                                  IPIs/s (sum of 4 core)
     1 mbuf  6735.98  6903.13  6971.89  7056.66   ~400K
     2 mbuf  7675.47  7757.28  7815.45  7514.50   ~240K
     4 mbuf  7895.33  7584.22  7704.12  7723.33   ~180K
     8 mbuf  8006.94  8077.87  7701.23  8061.12   ~120K
    16 mbuf  8151.68  8023.03  7972.42  8046.13   ~100K
    
    The default value (2) for the sosnd_agglim improve the whole
    performance by ~10%.  IPI rate is also reduce greatly.
    
    It has no obvious impact on 1000BaseT or 100baseTX network performace.

Summary of changes:
 sys/kern/uipc_socket.c  |    7 ++++++-
 sys/netinet/tcp_input.c |    3 +++
 2 files changed, 9 insertions(+), 1 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/c16aca65782c69370a255842c2e43ad127e5249d


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