netdev - Re: Re: limited network bandwidth with 3.2.x kernels

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Date:	Thu, 16 Feb 2012 13:19:58 -0500
From:	Neal Cardwell <ncardwell@...gle.com>
To:	alekcejk@...glemail.com
Cc:	netdev@...r.kernel.org
Subject: Re: Re: limited network bandwidth with 3.2.x kernels

On Thu, Feb 16, 2012 at 12:54 PM,  <alekcejk@...glemail.com> wrote:

> Looks like  "ethtool -k eth0" shows the same with both kernels:
>
> Offload parameters for eth0:
> rx-checksumming: on
> tx-checksumming: on
> scatter-gather: on
> tcp-segmentation-offload: off
> udp-fragmentation-offload: off
> generic-segmentation-offload: on
> generic-receive-offload: on
> large-receive-offload: off
> rx-vlan-offload: off
> tx-vlan-offload: off
> ntuple-filters: off
> receive-hashing: off

Great. Thanks, Alexey.

I still think it would be useful to have these three pieces of data
for a slow/3.2.x transfer (from a geographically distant server) if
you have a sec:

- tcpdump of first 300 or so packets to see SYN/SYNACK options and RTT

- tcpdump of _last_ 300 or so packets, to see the steady-state dynamics
 with receiver window and packet inter-arrival times

- summary of overall throughput wget sees on that transfer

This should help establish whether the receiver window is really the
limiting factor in the slow cases.

neal
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