Re: [PATCH] virtio: Fix stats issue

[Thomas Monjalon <thomas.monjalon-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>]

2015-03-23 16:38, Ouyang, Changchun:
> On 3/23/2015 3:20 PM, David Marchand wrote:
> > On Mon, Mar 23, 2015 at 7:56 AM, Ouyang Changchun 
> > <changchun.ouyang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org <mailto:changchun.ouyang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>> wrote:
> >
> >     It need clear/reset the stats information before count in all
> >     queues data.
> >
> >     Signed-off-by: Changchun Ouyang <changchun.ouyang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org
> >     <mailto:changchun.ouyang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>>
> >     ---
> >      lib/librte_pmd_virtio/virtio_ethdev.c | 8 ++++++++
> >      1 file changed, 8 insertions(+)
> >
> >     diff --git a/lib/librte_pmd_virtio/virtio_ethdev.c
> >     b/lib/librte_pmd_virtio/virtio_ethdev.c
> >     index 603be2d..e4cb55e 100644
> >     --- a/lib/librte_pmd_virtio/virtio_ethdev.c
> >     +++ b/lib/librte_pmd_virtio/virtio_ethdev.c
> >     @@ -572,6 +572,10 @@ virtio_dev_stats_get(struct rte_eth_dev *dev,
> >     struct rte_eth_stats *stats)
> >      {
> >             unsigned i;
> >
> >     +       stats->opackets = 0;
> >     +       stats->obytes = 0;
> >     +       stats->oerrors = 0;
> >
> >
> > stats are supposed to be zero'd in generic rte_ethdev.c before this 
> > pmd function is called, so this patch seems useless to me.
> > Can you give some context ?
> >
> > Same comment for the i* part.
> >
> 2 reasons:
> 1. this change could keep the stats_get has consistent behavior with the 
> one in other drivers;

If there are some useless reset in other drivers, they should be removed.

> 2. we don't rely on the assumption of caller always zero'd the stats, 
> and still can return correct value;

The caller is ethdev and it is zero'ing the structure before the call:
	http://dpdk.org/browse/dpdk/commit/?id=02331c16ec0