Full 32bit flowid from igb(4)

[hiren panchasara]

On 03/24/15 at 01:51P, Adrian Chadd wrote:
> Hi,
> 
> The main reason I didn't add it outside of RSS is that I didn't want
> to impact the behaviour that was there before. Before, it wasn't using
> the flowid - only the msix/queue id.

It'd break things if not all igb chips behave the same way in this
regard. In which case, we'd have to fix them on per-case basis by
pointing broken ones to the old behavior.
> 
> I read the intel datasheets about that particular field - I'm pretty
> sure that by default we'll only see RSS hashed packets for IPv4/IPv6,
> however non v4/v6 packets won't have a flowid.

I guess that'd be okay for tiny traffic going through non-hashed.
> There are also cases of
> the flow director or some hardware checksum config using the same
> field as the flowid.

I don't understand your point here. Which field do you refer to as
"the same field"? Can you please explain a bit more?
> 
> The /full/ solution would very carefully check the return status and
> ensure what's in the flowid field is a flowid.

Yes, I am waiting for Eric or Jack to comment on it.
> 
> The "sometimes it may have a flowid, sometimes it won't" problem isn't
> so bad with kernel RSS enabled - it'll just software hash it.

True.

Cheers,
Hiren
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