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SubjectRe: [RFC net-next 0/2] mvpp2: page_pool support
On Tue, 24 Dec 2019 14:34:07 +0100
Matteo Croce <mcroce@redhat.com> wrote:

> On Tue, Dec 24, 2019 at 10:52 AM Ilias Apalodimas
> <ilias.apalodimas@linaro.org> wrote:
> >
> > On Tue, Dec 24, 2019 at 02:01:01AM +0100, Matteo Croce wrote:
> > > This patches change the memory allocator of mvpp2 from the frag allocator to
> > > the page_pool API. This change is needed to add later XDP support to mvpp2.
> > >
> > > The reason I send it as RFC is that with this changeset, mvpp2 performs much
> > > more slower. This is the tc drop rate measured with a single flow:
> > >
> > > stock net-next with frag allocator:
> > > rx: 900.7 Mbps 1877 Kpps
> > >
> > > this patchset with page_pool:
> > > rx: 423.5 Mbps 882.3 Kpps
> > >
> > > This is the perf top when receiving traffic:
> > >
> > > 27.68% [kernel] [k] __page_pool_clean_page
> >
> > This seems extremly high on the list.
> >
> > > 9.79% [kernel] [k] get_page_from_freelist
> > > 7.18% [kernel] [k] free_unref_page
> > > 4.64% [kernel] [k] build_skb
> > > 4.63% [kernel] [k] __netif_receive_skb_core
> > > 3.83% [mvpp2] [k] mvpp2_poll
> > > 3.64% [kernel] [k] eth_type_trans
> > > 3.61% [kernel] [k] kmem_cache_free
> > > 3.03% [kernel] [k] kmem_cache_alloc
> > > 2.76% [kernel] [k] dev_gro_receive
> > > 2.69% [mvpp2] [k] mvpp2_bm_pool_put
> > > 2.68% [kernel] [k] page_frag_free
> > > 1.83% [kernel] [k] inet_gro_receive
> > > 1.74% [kernel] [k] page_pool_alloc_pages
> > > 1.70% [kernel] [k] __build_skb
> > > 1.47% [kernel] [k] __alloc_pages_nodemask
> > > 1.36% [mvpp2] [k] mvpp2_buf_alloc.isra.0
> > > 1.29% [kernel] [k] tcf_action_exec
> > >
> > > I tried Ilias patches for page_pool recycling, I get an improvement
> > > to ~1100, but I'm still far than the original allocator.
> >
> > Can you post the recycling perf for comparison?
> >
>
> 12.00% [kernel] [k] get_page_from_freelist
> 9.25% [kernel] [k] free_unref_page

Hmm, this indicate pages are not getting recycled.

> 6.83% [kernel] [k] eth_type_trans
> 5.33% [kernel] [k] __netif_receive_skb_core
> 4.96% [mvpp2] [k] mvpp2_poll
> 4.64% [kernel] [k] kmem_cache_free
> 4.06% [kernel] [k] __xdp_return

You do invoke __xdp_return() code, but it might find that the page
cannot be recycled...

> 3.60% [kernel] [k] kmem_cache_alloc
> 3.31% [kernel] [k] dev_gro_receive
> 3.29% [kernel] [k] __page_pool_clean_page
> 3.25% [mvpp2] [k] mvpp2_bm_pool_put
> 2.73% [kernel] [k] __page_pool_put_page
> 2.33% [kernel] [k] __alloc_pages_nodemask
> 2.33% [kernel] [k] inet_gro_receive
> 2.05% [kernel] [k] __build_skb
> 1.95% [kernel] [k] build_skb
> 1.89% [cls_matchall] [k] mall_classify
> 1.83% [kernel] [k] page_pool_alloc_pages
> 1.80% [kernel] [k] tcf_action_exec
> 1.70% [mvpp2] [k] mvpp2_buf_alloc.isra.0
> 1.63% [kernel] [k] free_unref_page_prepare.part.0
> 1.45% [kernel] [k] page_pool_return_skb_page
> 1.42% [act_gact] [k] tcf_gact_act
> 1.16% [kernel] [k] netif_receive_skb_list_internal
> 1.08% [kernel] [k] kfree_skb
> 1.07% [kernel] [k] skb_release_data

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

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