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Subject[RFC net-next 0/2] mvpp2: page_pool support
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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
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.

Any idea on why I get such bad numbers?

Another reason to send it as RFC is that I'm not fully convinced on how to
use the page_pool given the HW limitation of the BM.

The driver currently uses, for every CPU, a page_pool for short packets and
another for long ones. The driver also has 4 rx queue per port, so every
RXQ #1 will share the short and long page pools of CPU #1.

This means that for every RX queue I call xdp_rxq_info_reg_mem_model() twice,
on two different page_pool, can this be a problem?

As usual, ideas are welcome.

Matteo Croce (2):
mvpp2: use page_pool allocator
mvpp2: memory accounting

drivers/net/ethernet/marvell/Kconfig | 1 +
drivers/net/ethernet/marvell/mvpp2/mvpp2.h | 7 +
.../net/ethernet/marvell/mvpp2/mvpp2_main.c | 142 +++++++++++++++---
3 files changed, 125 insertions(+), 25 deletions(-)

--
2.24.1

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