netdev - Re: [net-next v4 11/11] page_pool: Add function to batch and return stats

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Date:   Fri, 4 Feb 2022 10:00:30 -0800
From:   Joe Damato <jdamato@...tly.com>
To:     Ilias Apalodimas <ilias.apalodimas@...aro.org>
Cc:     netdev@...r.kernel.org, kuba@...nel.org, davem@...emloft.net,
        hawk@...nel.org, saeed@...nel.org, ttoukan.linux@...il.com,
        brouer@...hat.com
Subject: Re: [net-next v4 11/11] page_pool: Add function to batch and return stats

On Thu, Feb 3, 2022 at 11:46 PM Ilias Apalodimas
<ilias.apalodimas@...aro.org> wrote:
>
> On Thu, Feb 03, 2022 at 04:09:33PM -0800, Joe Damato wrote:
> > Adds a function page_pool_get_stats which can be used by drivers to obtain
> > the batched stats for a specified page pool.
> >
> > Signed-off-by: Joe Damato <jdamato@...tly.com>
> > ---
> >  include/net/page_pool.h |  9 +++++++++
> >  net/core/page_pool.c    | 25 +++++++++++++++++++++++++
> >  2 files changed, 34 insertions(+)
> >
> > diff --git a/include/net/page_pool.h b/include/net/page_pool.h
> > index bb87706..5257e46 100644
> > --- a/include/net/page_pool.h
> > +++ b/include/net/page_pool.h
> > @@ -153,6 +153,15 @@ struct page_pool_stats {
> >               u64 waive;  /* failed refills due to numa zone mismatch */
> >       } alloc;
> >  };
> > +
> > +/*
> > + * Drivers that wish to harvest page pool stats and report them to users
> > + * (perhaps via ethtool, debugfs, or another mechanism) can allocate a
> > + * struct page_pool_stats and call page_pool_get_stats to get the batched pcpu
> > + * stats.
> > + */
> > +struct page_pool_stats *page_pool_get_stats(struct page_pool *pool,
> > +                                         struct page_pool_stats *stats);
> >  #endif
> >
> >  struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
> > diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> > index 0bd084c..076593bb 100644
> > --- a/net/core/page_pool.c
> > +++ b/net/core/page_pool.c
> > @@ -35,6 +35,31 @@
> >               struct page_pool_stats __percpu *s = pool->stats;       \
> >               __this_cpu_inc(s->alloc.__stat);                        \
> >       } while (0)
> > +
> > +struct page_pool_stats *page_pool_get_stats(struct page_pool *pool,
> > +                                         struct page_pool_stats *stats)
> > +{
> > +     int cpu = 0;
> > +
> > +     if (!stats)
> > +             return NULL;
> > +
> > +     for_each_possible_cpu(cpu) {
> > +             const struct page_pool_stats *pcpu =
> > +                     per_cpu_ptr(pool->stats, cpu);
> > +
> > +             stats->alloc.fast += pcpu->alloc.fast;
> > +             stats->alloc.slow += pcpu->alloc.slow;
> > +             stats->alloc.slow_high_order +=
> > +                     pcpu->alloc.slow_high_order;
> > +             stats->alloc.empty += pcpu->alloc.empty;
> > +             stats->alloc.refill += pcpu->alloc.refill;
> > +             stats->alloc.waive += pcpu->alloc.waive;
> > +     }
> > +
> > +     return stats;
> > +}
> > +EXPORT_SYMBOL(page_pool_get_stats);
>
> You don't really need to return a pointer here. Just make the return code a
> bool

OK. Updated page_pool_get_stats to return a bool in my v5 branch.