On Wed, 23 Sep 2009 09:57:51 -0700
Ben Greear [off-list ref] wrote:

On 09/23/2009 09:53 AM, Stephen Hemminger wrote:

quoted

On Wed, 23 Sep 2009 09:29:59 -0700
Ben Greear[off-list ref]  wrote:

quoted

I just noticed that enabling LRO on ixgbe lets me reach about 9Gbps receive on two
NICs concurrently in an NFS test, where I was only getting about 6Gbps w/out it (1500 MTU).

Why is LRO disabled by default?

Thanks,
Ben

LRO is turned off if bridging or routing because of End to End requirements.

That makes sense.

If I know that all interfaces in question can handle TSO and LRO,
I could manually enable LRO w/out risk, right?

The problem is that LRO merges TCP packets, this breaks the end-to-end
ack clocking and checksumming, and therefore is not enabled.
That is why GRO is the replacement solution (preserves packet boundaries)