Liang Chen f7dc3248dc skbuff: Optimization of SKB coalescing for page pool ... In order to address the issues encountered with commit 1effe8ca4e ("skbuff: fix coalescing for page_pool fragment recycling"), the combination of the following condition was excluded from skb coalescing: from->pp_recycle = 1 from->cloned = 1 to->pp_recycle = 1 However, with page pool environments, the aforementioned combination can be quite common(ex. NetworkMananger may lead to the additional packet_type being registered, thus the cloning). In scenarios with a higher number of small packets, it can significantly affect the success rate of coalescing. For example, considering packets of 256 bytes size, our comparison of coalescing success rate is as follows: Without page pool: 70% With page pool: 13% Consequently, this has an impact on performance: Without page pool: 2.57 Gbits/sec With page pool: 2.26 Gbits/sec Therefore, it seems worthwhile to optimize this scenario and enable coalescing of this particular combination. To achieve this, we need to ensure the correct increment of the "from" SKB page's page pool reference count (pp_ref_count). Following this optimization, the success rate of coalescing measured in our environment has improved as follows: With page pool: 60% This success rate is approaching the rate achieved without using page pool, and the performance has also been improved: With page pool: 2.52 Gbits/sec Below is the performance comparison for small packets before and after this optimization. We observe no impact to packets larger than 4K. packet size before after improved (bytes) (Gbits/sec) (Gbits/sec) 128 1.19 1.27 7.13% 256 2.26 2.52 11.75% 512 4.13 4.81 16.50% 1024 6.17 6.73 9.05% 2048 14.54 15.47 6.45% 4096 25.44 27.87 9.52% Signed-off-by: Liang Chen <liangchen.linux@gmail.com> Reviewed-by: Yunsheng Lin <linyunsheng@huawei.com> Suggested-by: Jason Wang <jasowang@redhat.com> Reviewed-by: Mina Almasry <almasrymina@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2023-12-17 10:56:33 +00:00
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helpers.h	skbuff: Optimization of SKB coalescing for page pool	2023-12-17 10:56:33 +00:00
types.h	page_pool: transition to reference count management after page draining	2023-12-13 18:35:16 -08:00