From 0fcf09d3d0d0ab1eff2380404449bee3311fa20d Mon Sep 17 00:00:00 2001 From: Wei Liu Date: Wed, 3 Jun 2015 11:10:42 +0100 Subject: [PATCH] tcp: double default TSQ output bytes limit 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 Cc: David Miller Cc: Eric Dumazet Acked-by: Eric Dumazet Signed-off-by: David S. Miller (cherry picked from commit c39c4c6abb89d24454b63798ccbae12b538206a5) Oracle-Bug: 25424818 Signed-off-by: Joao Martins Tested-by: Raj Matharasi Acked-by: Konrad Rzeszutek Wilk --- 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 a369e8a70b2c..6d25d31f115d 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 -- 2.50.1