how tso (tcp segmentation offload) effect TCP bidirectional test sending throughput.

how tso (tcp segmentation offload) effect TCP bidirectional test sending throughput.

[Varun Sharma]

Hi,

if we off tso (tcp segmentation offload) on sending side ,  *TCP
Bidirectional* test sending throughput decrease as compare to *TCP
Unidirectional *test sending throughput .

whereas if we on tso(tcp segmentation offload) on sending side , both
testgive almost same
sending throughput result.

is anyone know how tso(tcp segmentation offload) effect TCP Bidirectional
sending throughput ?

i am using iperf-2.0.5 for this case.

Thanks in advance.

Regards
varun
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20140411/1dd6ea20/attachment.html 

how tso (tcp segmentation offload) effect TCP bidirectional test sending throughput.

[Abu Rasheda]

On Fri, Apr 11, 2014 at 3:10 AM, Varun Sharma <vsdssd@gmail.com> wrote:

> Hi,
>
> if we off tso (tcp segmentation offload) on sending side ,  *TCP
> Bidirectional* test sending throughput decrease as compare to *TCP
> Unidirectional *test sending throughput .
>
> whereas if we on tso(tcp segmentation offload) on sending side , both testgive almost same
> sending throughput result.
>
> is anyone know how tso(tcp segmentation offload) effect TCP Bidirectional
> sending throughput ?
>
> i am using iperf-2.0.5 for this case.
>
> There are couple of things here.

1. Depending on the NIC, it could potentially have hardware offload in the
hardware. So offing TSO might not off it.
2. There is Linux kernel offload for receive, so there might be kernel
offload for send also
3. Different cards deal with offloading differently, with very different
result
4. If TSO is actually off, it might mean that eventually acks from remote
side are delayed filling its buffers

So this is very card, kernel version dependent.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20140411/46d8fe9a/attachment.html 

how tso (tcp segmentation offload) effect TCP bidirectional test sending throughput.

[michi1 at michaelblizek.twilightparadox.com]

Hi!

On 15:40 Fri 11 Apr     , Varun Sharma wrote:
> Hi,
> 
> if we off tso (tcp segmentation offload) on sending side ,  *TCP
> Bidirectional* test sending throughput decrease as compare to *TCP
> Unidirectional *test sending throughput .
> 
> whereas if we on tso(tcp segmentation offload) on sending side , both
> testgive almost same
> sending throughput result.
> 
> is anyone know how tso(tcp segmentation offload) effect TCP Bidirectional
> sending throughput ?

TSO reduces cpu usage. Your cpu might be a bottleneck with TSO off.

	-Michi
-- 
programing a layer 3+4 network protocol for mesh networks
see http://michaelblizek.twilightparadox.com