Re: [PATCH REPOST libibverbs] Add IP and TCP/UDP TX checksum offload support

[Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

[-- Attachment #1: Type: text/plain, Size: 1562 bytes --]

On 07/01/2015 11:17 AM, Christoph Lameter wrote:
> Is there any release schedule and/or upstream repo where I can see changes
> for libibverbs and libmlx4?
> 

I'm working on libibverbs right now.  The upstream git repo has not
changed, it's the same as it always was.

Or, Jason asked for some (IMO very much needed) documentation on this
feature via man page additions.  For instance, the changelog calls out
that this is only used for TCP/UDP packets over IB UD QPs or Eth Raw
QPs.  Well, IB UD QPs sending IP packets is IPoIB, which is generally a
kernel protocol.  So, when it comes to user space, is this realistically
a Raw Eth QP only thing?

Also, the man page entry calls out what I would classify as hardware
limitations in the general IB verbs man page.  I would think it would
more appropriately call out that the support is hardware dependent and
then provide some means for the hardware to specify what types of IP
CSUM offloads it supports.  For instance, although there's been talk of
making connected mode IPoIB go faster by dropping the TCP checksum and
relying on the RC EC code instead and just ignoring the TCP checksum.
Another alternative would be to add TCP checksum support to your
firmware for connected mode QPs, so it's possible that in the future the
types of IP CSUM support could grow.  This patchset doesn't allow for
that or for distinguishing between hardware that has new or old firmware.

-- 
Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
              GPG KeyID: 0E572FDD



[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 884 bytes --]