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[Xen-devel] Re: [GIT/PATCH v4] xen network backend driver

To: Ben Hutchings <bhutchings@xxxxxxxxxxxxxx>
Subject: [Xen-devel] Re: [GIT/PATCH v4] xen network backend driver
From: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>
Date: Fri, 11 Mar 2011 10:22:55 +0000
Cc: Fitzhardinge <jeremy@xxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Jeremy, Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, "netdev@xxxxxxxxxxxxxxx" <netdev@xxxxxxxxxxxxxxx>, Francois Romieu <romieu@xxxxxxxxxxxxx>, Stephen Hemminger <shemminger@xxxxxxxxxx>
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On Thu, 2011-03-10 at 17:30 +0000, Ben Hutchings wrote:
> On Thu, 2011-03-10 at 09:15 -0800, Stephen Hemminger wrote:
> > On Thu, 10 Mar 2011 17:02:33 +0000
> > Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> > > +struct xenvif {
> > > + /* Unique identifier for this interface. */
> > ...
> > > + struct net_device_stats stats;
> > > +
> > 
> > There is already a stats struct in net_device in current kernel
> > versions, unless there is a compelling reason otherwise
> > please use that.

Will do.
> > Also, you probably want to implement per-cpu and 64 bit
> > stats.
> The driver is using a single queue, so I don't see what benefit it would
> get from per-cpu stats.  At some point it should become multiqueue and
> then it should store per-queue stats.


> 64-bit stats are definitely preferable, but since they're being
> maintained on the data path this may require some significant work.
> (Ian: see <linux/u64_stats_sync.h> for the canonical way to do this.)
> Given that only a relatively few existing drivers do this (I count 13),
> I'm not sure we can reasonably demand that a new driver does - yet.

Is there an example of a driver which also updates the stats on the

If it's ok I'd prefer to defer this change for now though.


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