Xen virtual network driver has higher latency than a physical NIC. Having only 128K as limit for TSQ introduced 30% regression in guest throughput.
This patch raises the limit to 256K. This reduces the regression to 8%. This buys us more time to work out a proper solution in the long run. Signed-off-by: Wei Liu <wei.l...@citrix.com> Cc: David Miller <da...@davemloft.net> Cc: Eric Dumazet <eric.duma...@gmail.com> --- net/ipv4/tcp_output.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 190538a..eeb59be 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -50,8 +50,8 @@ int sysctl_tcp_retrans_collapse __read_mostly = 1; */ int sysctl_tcp_workaround_signed_windows __read_mostly = 0; -/* Default TSQ limit of two TSO segments */ -int sysctl_tcp_limit_output_bytes __read_mostly = 131072; +/* Default TSQ limit of four TSO segments */ +int sysctl_tcp_limit_output_bytes __read_mostly = 262144; /* This limits the percentage of the congestion window which we * will allow a single TSO frame to consume. Building TSO frames -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
