On 09/21/2012 03:32 PM, Marcelo Ricardo Leitner wrote:

On 09/20/2012 12:04 PM, Marcelo Ricardo Leitner wrote:

quoted

On 09/20/2012 10:21 AM, Or Gerlitz wrote:

quoted

On 20/09/2012 03:43, Marcelo Ricardo Leitner wrote:

quoted

I have a report that our mlx4 driver (RHEL 6.3) is dropping multicast
packets when NIC leaves promisc mode. It seems this is being cause due
to the new steering mode that took place near by commit
1679200f91da6a054b06954c9bd3eeed29b6731f. As it seems, the new
steering mode needs more commands/time to leave the promisc mode,
which may be leading to packet drops.

Marcelo,

The commit you point on below 6d19993 "net/mlx4_en: Re-design multicast
attachments flow" makes sure to avoid
doing extra firmware comments and not leave a window in time where
"correct" addresses are not attached. Its hard to say what's the case on
that RHEL 6.3 system, it would be very helpful through if you manage to
reproduce the problem on an upstream kernel -- BTW you didn't say on

Okay, I understand that the commit prevents a window. I may be missing
something, but isn't there another one in there? Between:
mlx4_SET_MCAST_FLTR MLX4_MCAST_DISABLE and
mlx4_SET_MCAST_FLTR MLX4_MCAST_ENABLE
because mlx4_multicast_promisc_remove() was called just before those.
Otherwise I don't how is the NIC would be receiving multicast packets in
there.

....

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And then I tried 3 additional patches applied at once:
- 60d31c1475f2 "net/mlx4_core: Looking for promiscuous entries on the
correct port"
- f1f75f0 - mlx4: attach multicast with correct flag
- Yes, this one wasn't in 2.6.32-279.el6.
- 6d19993 - net/mlx4_en: Re-design multicast attachments flow

And they still reported drops.

Well, neither me nor they could reproduce the drops at promisc exit 
anymore. It's hard to chase a ghost, you know. I'll still track that cpu 
usage, but it seems unrelated to the driver at first glance.

Thank you for your support Or, appreciated.

Regards,
Marcelo