Re: [Xen-devel] [PATCH net-next v5 0/9] xen-netback: TX grant mapping with SKBTX_DEV_ZEROCOPY instead of copy

[Zoltan Kiss <zoltan.kiss@xxxxxxxxxx>]

On 23/01/14 01:50, David Miller wrote:
> From: Zoltan Kiss <zoltan.kiss@xxxxxxxxxx>
> Date: Mon, 20 Jan 2014 21:24:20 +0000
>
> > A long known problem of the upstream netback implementation that on the TX
> > path (from guest to Dom0) it copies the whole packet from guest memory into
> > Dom0. That simply became a bottleneck with 10Gb NICs, and generally it's a
> > huge perfomance penalty. The classic kernel version of netback used grant
> > mapping, and to get notified when the page can be unmapped, it used page
> > destructors. Unfortunately that destructor is not an upstreamable solution.
> > Ian Campbell's skb fragment destructor patch series [1] tried to solve this
> > problem, however it seems to be very invasive on the network stack's code,
> > and therefore haven't progressed very well.
> > This patch series use SKBTX_DEV_ZEROCOPY flags to tell the stack it needs to
> > know when the skb is freed up.
> This series does not apply to net-next due to some other recent changes.
>
> Please respin, thanks.
It is already based on two predecessor patches, one which is already 
accepted but not applied yet:
[PATCH net-next v2] xen-netback: Rework rx_work_todo

And the other one is hopefully will be accepted very soon:

[PATCH v5] xen/grant-table: Avoid m2p_override during mapping

Zoli


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