[Xen-devel] Fwd: Re: xennet: skb rides the rocket: 20 slots

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

This is a forwarded message
From: ANNIE LI <annie.li@xxxxxxxxxx>
To: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
Date: Monday, January 14, 2013, 10:39:53 AM
Subject: [Xen-devel] xennet: skb rides the rocket: 20 slots


Resend because xen-devel wasn't copied on the original ...


===8<==============Original message text===============
Hi

I created a patch for this, but I failed to reproduce this issue and 
verify it. The patch was attached,

Thanks
Annie

On 2013-1-11 18:16, Ian Campbell wrote:
> On Fri, 2013-01-11 at 10:09 +0000, Paul Durrant wrote:
>>> -----Original Message-----
>>> Without GSO I don't think you should be seeing packets larger than the MTU,
>>> which would normally be either ~1500 or ~9000 and fit easily within any
>>> sensible negotiation for the max frags. I don't think you should worry 
>>> unduly
>>> about this case.
>>>
>> A stack could still send down a packet with one byte per frag though,
>> right? A copy-and-coalesce path would still be needed in this case.
> True. In that case skb_linearise would probably do the job on Linux.
>
> Ian
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxx
> http://lists.xen.org/xen-devel

===8<===========End of original message text===========

--- Begin Message ---

• To: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
• From: ANNIE LI <annie.li@xxxxxxxxxx>
• Date: Mon, 14 Jan 2013 17:39:53 +0800
• Cc: Paul Durrant <Paul.Durrant@xxxxxxxxxx>, Sander Eikelenboom <linux@xxxxxxxxxxxxxx>, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
• Delivery-date: Mon, 14 Jan 2013 10:45:09 +0100

Hi

I created a patch for this, but I failed to reproduce this issue and verify it. The patch was attached,

Thanks
Annie

On 2013-1-11 18:16, Ian Campbell wrote:

On Fri, 2013-01-11 at 10:09 +0000, Paul Durrant wrote:

-----Original Message-----
Without GSO I don't think you should be seeing packets larger than the MTU,
which would normally be either ~1500 or ~9000 and fit easily within any
sensible negotiation for the max frags. I don't think you should worry unduly
about this case.

A stack could still send down a packet with one byte per frag though,
right? A copy-and-coalesce path would still be needed in this case.

True. In that case skb_linearise would probably do the job on Linux.

Ian


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