[dpdk-dev] DPDK testpmd forwarding performace degradation
吴亚东
wuyd at outlook.com
Tue Jan 27 03:49:27 CET 2015
65 bytes frame may degrade performace a lot.Thats related to DMA and cache.
When NIC dma packets to memory, NIC has to do read modify write if DMA size is partial cache line.So for 65 bytes, the first 64 bytes are ok. The next 1 byte NIC has to read the whole cache line, change one byte and update the cache line.
So in DPDK, CRC is not stripped and ethernet header aligned to cache line which causes ip header not aligned on 4 bytes.
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