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authorstephen hemminger <shemminger@vyatta.com>2011-03-14 07:52:16 +0000
committerDavid S. Miller <davem@davemloft.net>2011-03-14 15:54:40 -0700
commit3b585b34493ec9db382d6c325d4ed77b9eb2d2a5 (patch)
treee3208425d46953bb587b2db6dfb521064f127aed /net/ipv4/tcp_cubic.c
parent17a6e9f1aa9ba07ca13a1eaf1e631e743af50cca (diff)
downloadlinux-3b585b34493ec9db382d6c325d4ed77b9eb2d2a5.tar.bz2
tcp_cubic: enable high resolution ack time if needed
This is a refined version of an earlier patch by Lucas Nussbaum. Cubic needs RTT values in milliseconds. If HZ < 1000 then the values will be too coarse. Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> Reported-by: Lucas Nussbaum <lucas.nussbaum@loria.fr> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_cubic.c')
-rw-r--r--net/ipv4/tcp_cubic.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/net/ipv4/tcp_cubic.c b/net/ipv4/tcp_cubic.c
index f4fb2d4b90ad..5e0491d742ca 100644
--- a/net/ipv4/tcp_cubic.c
+++ b/net/ipv4/tcp_cubic.c
@@ -459,6 +459,10 @@ static int __init cubictcp_register(void)
/* divide by bic_scale and by constant Srtt (100ms) */
do_div(cube_factor, bic_scale * 10);
+ /* hystart needs ms clock resolution */
+ if (hystart && HZ < 1000)
+ cubictcp.flags |= TCP_CONG_RTT_STAMP;
+
return tcp_register_congestion_control(&cubictcp);
}