linux-kernel - Re: [PATCH net-next v3] net: page_pool: optimize page pool page allocation in NUMA scenario

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Date:   Fri, 8 Jul 2022 00:48:58 +0300
From:   Ilias Apalodimas <ilias.apalodimas@...aro.org>
To:     Jesper Dangaard Brouer <jbrouer@...hat.com>
Cc:     Guangbin Huang <huangguangbin2@...wei.com>, hawk@...nel.org,
        davem@...emloft.net, kuba@...nel.org, edumazet@...gle.com,
        pabeni@...hat.com, brouer@...hat.com, lorenzo@...nel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        bpf@...r.kernel.org, lipeng321@...wei.com, chenhao288@...ilicon.com
Subject: Re: [PATCH net-next v3] net: page_pool: optimize page pool page
 allocation in NUMA scenario

On Thu, 7 Jul 2022 at 22:14, Jesper Dangaard Brouer <jbrouer@...hat.com> wrote:
>
>
> On 05/07/2022 13.35, Guangbin Huang wrote:
> > From: Jie Wang <wangjie125@...wei.com>
> >
> > Currently NIC packet receiving performance based on page pool deteriorates
> > occasionally. To analysis the causes of this problem page allocation stats
> > are collected. Here are the stats when NIC rx performance deteriorates:
> >
> > bandwidth(Gbits/s)            16.8            6.91
> > rx_pp_alloc_fast              13794308        21141869
> > rx_pp_alloc_slow              108625          166481
> > rx_pp_alloc_slow_h            0               0
> > rx_pp_alloc_empty             8192            8192
> > rx_pp_alloc_refill            0               0
> > rx_pp_alloc_waive             100433          158289
> > rx_pp_recycle_cached          0               0
> > rx_pp_recycle_cache_full      0               0
> > rx_pp_recycle_ring            362400          420281
> > rx_pp_recycle_ring_full               6064893         9709724
> > rx_pp_recycle_released_ref    0               0
> >
> > The rx_pp_alloc_waive count indicates that a large number of pages' numa
> > node are inconsistent with the NIC device numa node. Therefore these pages
> > can't be reused by the page pool. As a result, many new pages would be
> > allocated by __page_pool_alloc_pages_slow which is time consuming. This
> > causes the NIC rx performance fluctuations.
> >
> > The main reason of huge numa mismatch pages in page pool is that page pool
> > uses alloc_pages_bulk_array to allocate original pages. This function is
> > not suitable for page allocation in NUMA scenario. So this patch uses
> > alloc_pages_bulk_array_node which has a NUMA id input parameter to ensure
> > the NUMA consistent between NIC device and allocated pages.
> >
> > Repeated NIC rx performance tests are performed 40 times. NIC rx bandwidth
> > is higher and more stable compared to the datas above. Here are three test
> > stats, the rx_pp_alloc_waive count is zero and rx_pp_alloc_slow which
> > indicates pages allocated from slow patch is relatively low.
> >
> > bandwidth(Gbits/s)            93              93.9            93.8
> > rx_pp_alloc_fast              60066264        61266386        60938254
> > rx_pp_alloc_slow              16512           16517           16539
> > rx_pp_alloc_slow_ho           0               0               0
> > rx_pp_alloc_empty             16512           16517           16539
> > rx_pp_alloc_refill            473841          481910          481585
> > rx_pp_alloc_waive             0               0               0
> > rx_pp_recycle_cached          0               0               0
> > rx_pp_recycle_cache_full      0               0               0
> > rx_pp_recycle_ring            29754145        30358243        30194023
> > rx_pp_recycle_ring_full               0               0               0
> > rx_pp_recycle_released_ref    0               0               0
> >
> > Signed-off-by: Jie Wang <wangjie125@...wei.com>
>
> Acked-by: Jesper Dangaard Brouer <brouer@...hat.com>
>
> > ---
> > v2->v3:
> > 1, Delete the #ifdefs
> > 2, Use 'pool->p.nid' in the call to alloc_pages_bulk_array_node()
> >
> > v1->v2:
> > 1, Remove two inappropriate comments.
> > 2, Use NUMA_NO_NODE instead of numa_mem_id() for code maintenance.
> > ---
> >   net/core/page_pool.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> > index f18e6e771993..b74905fcc3a1 100644
> > --- a/net/core/page_pool.c
> > +++ b/net/core/page_pool.c
> > @@ -389,7 +389,8 @@ static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
> >       /* Mark empty alloc.cache slots "empty" for alloc_pages_bulk_array */
> >       memset(&pool->alloc.cache, 0, sizeof(void *) * bulk);
> >
> > -     nr_pages = alloc_pages_bulk_array(gfp, bulk, pool->alloc.cache);
> > +     nr_pages = alloc_pages_bulk_array_node(gfp, pool->p.nid, bulk,
> > +                                            pool->alloc.cache);
> >       if (unlikely(!nr_pages))
> >               return NULL;
> >
>

Acked-by: Ilias Apalodimas <ilias.apalodimas@...aro.org>