* [PATCH net-next] tcp: double default TSQ output bytes limit
@ 2015-06-03 10:10 Wei Liu
2015-06-04 6:51 ` Eric Dumazet
2015-06-04 8:09 ` David Miller
0 siblings, 2 replies; 3+ messages in thread
From: Wei Liu @ 2015-06-03 10:10 UTC (permalink / raw)
To: netdev
Cc: Stefano Stabellini, George Dunlap, Wei Liu, David Miller,
Eric Dumazet
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.liu2@citrix.com>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH net-next] tcp: double default TSQ output bytes limit
2015-06-03 10:10 [PATCH net-next] tcp: double default TSQ output bytes limit Wei Liu
@ 2015-06-04 6:51 ` Eric Dumazet
2015-06-04 8:09 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: Eric Dumazet @ 2015-06-04 6:51 UTC (permalink / raw)
To: Wei Liu; +Cc: netdev, Stefano Stabellini, George Dunlap, David Miller
On Wed, 2015-06-03 at 11:10 +0100, Wei Liu wrote:
> 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.liu2@citrix.com>
> Cc: David Miller <davem@davemloft.net>
> Cc: Eric Dumazet <eric.dumazet@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
Acked-by: Eric Dumazet <edumazet@google.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH net-next] tcp: double default TSQ output bytes limit
2015-06-03 10:10 [PATCH net-next] tcp: double default TSQ output bytes limit Wei Liu
2015-06-04 6:51 ` Eric Dumazet
@ 2015-06-04 8:09 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: David Miller @ 2015-06-04 8:09 UTC (permalink / raw)
To: wei.liu2; +Cc: netdev, stefano.stabellini, george.dunlap, eric.dumazet
From: Wei Liu <wei.liu2@citrix.com>
Date: Wed, 3 Jun 2015 11:10:42 +0100
> 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.liu2@citrix.com>
Applied, thanks.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2015-06-04 6:51 ` Eric Dumazet
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