netdev - Re: [PATCH v3 net-next 1/2] net: page

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Message-ID: <YlQjC7qpFXU7vmiH@lore-desk>
Date:   Mon, 11 Apr 2022 14:46:03 +0200
From:   Lorenzo Bianconi <lorenzo@...nel.org>
To:     Ilias Apalodimas <ilias.apalodimas@...aro.org>
Cc:     netdev@...r.kernel.org, lorenzo.bianconi@...hat.com,
        davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
        thomas.petazzoni@...tlin.com, linux@...linux.org.uk,
        jbrouer@...hat.com, jdamato@...tly.com, andrew@...n.ch
Subject: Re: [PATCH v3 net-next 1/2] net: page_pool: introduce ethtool stats

On Apr 11, Ilias Apalodimas wrote:
> On Mon, 11 Apr 2022 at 15:28, Lorenzo Bianconi <lorenzo@...nel.org> wrote:
> >
> > > Hi Lorenzo,
> >
> > Hi Ilias,
> >
> > >
> > > [...]
> > >
> > > >
> > > >         for_each_possible_cpu(cpu) {
> > > >                 const struct page_pool_recycle_stats *pcpu =
> > > > @@ -66,6 +87,47 @@ bool page_pool_get_stats(struct page_pool *pool,
> > > >         return true;
> > > >  }
> > > >  EXPORT_SYMBOL(page_pool_get_stats);
> > > > +
> > > > +u8 *page_pool_ethtool_stats_get_strings(u8 *data)
> > > > +{
> > > > +       int i;
> > > > +
> > > > +       for (i = 0; i < ARRAY_SIZE(pp_stats); i++) {
> > > > +               memcpy(data, pp_stats[i], ETH_GSTRING_LEN);
> > > > +               data += ETH_GSTRING_LEN;
> > > > +       }
> > > > +
> > > > +       return data;
> > >
> > > Is there a point returning data here or can we make this a void?
> >
> > it is to add the capability to add more strings in the driver code after
> > running page_pool_ethtool_stats_get_strings.
> 
> But the current driver isn't using it.  I don't have too much
> experience with how drivers consume ethtool stats, but would it make
> more sense to return a length instead of a pointer? Maybe Andrew has
> an idea.

yes, but it is for future usage. Returning a pointer modified by a
local routine is a common approach in the kernel (not sure about ethtool)
and it seems straightforward to me but len is fine as well. Opinions?

Regards,
Lorenzo

> 
> Thanks
> /Ilias
> >
> > >
> > > > +}
> > > > +EXPORT_SYMBOL(page_pool_ethtool_stats_get_strings);
> > > > +
> > > > +int page_pool_ethtool_stats_get_count(void)
> > > > +{
> > > > +       return ARRAY_SIZE(pp_stats);
> > > > +}
> > > > +EXPORT_SYMBOL(page_pool_ethtool_stats_get_count);
> > > > +
> > > > +u64 *page_pool_ethtool_stats_get(u64 *data, struct page_pool_stats *stats)
> > > > +{
> > > > +       int i;
> > > > +
> > > > +       for (i = 0; i < ARRAY_SIZE(pp_stats); i++) {
> > > > +               *data++ = stats->alloc_stats.fast;
> > > > +               *data++ = stats->alloc_stats.slow;
> > > > +               *data++ = stats->alloc_stats.slow_high_order;
> > > > +               *data++ = stats->alloc_stats.empty;
> > > > +               *data++ = stats->alloc_stats.refill;
> > > > +               *data++ = stats->alloc_stats.waive;
> > > > +               *data++ = stats->recycle_stats.cached;
> > > > +               *data++ = stats->recycle_stats.cache_full;
> > > > +               *data++ = stats->recycle_stats.ring;
> > > > +               *data++ = stats->recycle_stats.ring_full;
> > > > +               *data++ = stats->recycle_stats.released_refcnt;
> > > > +       }
> > > > +
> > > > +       return data;
> > >
> > > Ditto
> >
> > same here.
> >
> > Regards,
> > Lorenzo
> >
> > >
> > > > +}
> > > > +EXPORT_SYMBOL(page_pool_ethtool_stats_get);
> > > >  #else
> > > >  #define alloc_stat_inc(pool, __stat)
> > > >  #define recycle_stat_inc(pool, __stat)
> > > > --
> > > > 2.35.1
> > > >
> > >
> > > Thanks
> > > /Ilias

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