On Fri, 2014-05-30 at 11:01 -0300, ezequiel.garcia@free-electrons.com
wrote:

Hello Eric,

On 30 May 06:13 AM, Eric Dumazet wrote:

quoted

On Fri, 2014-05-30 at 09:42 +0000, fugang.duan@freescale.com wrote:

quoted

From: David Laight <redacted> Data: Friday, May 30, 2014 5:11 PM

quoted

Does the driver support BQL (or similar) in order to limit the amount of
queued tx traffic?
Otherwise you've significantly increased the latency for connections other
than one doing bulk tx.

David

The driver still don't support BQL.
I will add the feature to support FEC. Thanks for your advise.

Note that a full size TSO packet (44 or 45 MSS) requires about 88 or 90
descriptors.

What's the rationale behing those numbers?

64KB TSO packet, with MSS=1460 -> 44 segments  (44*1460 = 64240)
with MSS=1448 (TCP timestamps) -> 45 segments  (45*1448 = 65160)

This software TSO emulation uses at least 2 descriptors per MSS

one descriptor to hold the headers (ethernet + ip + tcp)
one descriptor (or two) to hold the payload for this MSS