netdev - Re: [PATCH v3 net-next 1/5] net: xdp: introduce bulking for xdp tx return path

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Date:   Wed, 4 Nov 2020 13:28:34 +0100
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     Lorenzo Bianconi <lorenzo.bianconi@...hat.com>
Cc:     Lorenzo Bianconi <lorenzo@...nel.org>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
        ilias.apalodimas@...aro.org, Ioana Ciornei <ioana.ciornei@....com>,
        Ioana Radulescu <ruxandra.radulescu@....com>, brouer@...hat.com
Subject: Re: [PATCH v3 net-next 1/5] net: xdp: introduce bulking for xdp tx
 return path

On Wed, 4 Nov 2020 12:19:02 +0100
Lorenzo Bianconi <lorenzo.bianconi@...hat.com> wrote:

> > On Wed,  4 Nov 2020 11:22:54 +0100
> > Lorenzo Bianconi <lorenzo@...nel.org> wrote:
> >   
> 
> [...]
> 
> > > +/* XDP bulk APIs introduce a defer/flush mechanism to return
> > > + * pages belonging to the same xdp_mem_allocator object
> > > + * (identified via the mem.id field) in bulk to optimize
> > > + * I-cache and D-cache.
> > > + * The bulk queue size is set to 16 to be aligned to how
> > > + * XDP_REDIRECT bulking works. The bulk is flushed when  
> > 
> > If this is connected, then why have you not redefined DEV_MAP_BULK_SIZE?
> > 
> > Cc. DPAA2 maintainers as they use this define in their drivers.
> > You want to make sure this driver is flexible enough for future changes.
> > 
> > Like:
> > 
> > diff --git a/include/net/xdp.h b/include/net/xdp.h
> > index 3814fb631d52..44440a36f96f 100644
> > --- a/include/net/xdp.h
> > +++ b/include/net/xdp.h
> > @@ -245,6 +245,6 @@ bool xdp_attachment_flags_ok(struct xdp_attachment_info *info,
> >  void xdp_attachment_setup(struct xdp_attachment_info *info,
> >                           struct netdev_bpf *bpf);
> >  
> > -#define DEV_MAP_BULK_SIZE 16
> > +#define DEV_MAP_BULK_SIZE XDP_BULK_QUEUE_SIZE  
> 
> my idea was to address it in a separated patch, but if you prefer I can merge
> this change in v4

Please merge in V4.  As this patch contains the explanation, and we
want to avoid too much churn (remember our colleagues need to backport
and review this).

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer