Messages in this thread | | | Date | Tue, 24 Dec 2019 15:00:58 +0100 | From | Jesper Dangaard Brouer <> | Subject | Re: [RFC net-next 0/2] mvpp2: page_pool support |
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On Tue, 24 Dec 2019 11:52:29 +0200 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.
This looks related to the cost of dma unmap, as page_pool have PP_FLAG_DMA_MAP. (It is a little strange, as page_pool have flag DMA_ATTR_SKIP_CPU_SYNC, which should make it less expensive).
> > 9.79% [kernel] [k] get_page_from_freelist
You are clearly hitting page-allocator every time, because you are not using page_pool recycle facility.
> > 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. -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer
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