f5472703c0
This patch optimizes rte_memcpy for well aligned cases, where both dst and src addr are aligned to maximum MOV width. It introduces a dedicated function called rte_memcpy_aligned to handle the aligned cases with simplified instruction stream. The existing rte_memcpy is renamed as rte_memcpy_generic. The selection between them 2 is done at the entry of rte_memcpy. The existing rte_memcpy is for generic cases, it handles unaligned copies and make store aligned, it even makes load aligned for micro architectures like Ivy Bridge. However alignment handling comes at a price: It adds extra load/store instructions, which can cause complications sometime. DPDK Vhost memcpy with Mergeable Rx Buffer feature as an example: The copy is aligned, and remote, and there is header write along which is also remote. In this case the memcpy instruction stream should be simplified, to reduce extra load/store, therefore reduce the probability of load/store buffer full caused pipeline stall, to let the actual memcpy instructions be issued and let H/W prefetcher goes to work as early as possible. This patch is tested on Ivy Bridge, Haswell and Skylake, it provides up to 20% gain for Virtio Vhost PVP traffic, with packet size ranging from 64 to 1500 bytes. The test can also be conducted without NIC, by setting loopback traffic between Virtio and Vhost. For example, modify the macro TXONLY_DEF_PACKET_LEN to the requested packet size in testpmd.h, rebuild and start testpmd in both host and guest, then "start" on one side and "start tx_first 32" on the other. Signed-off-by: Zhihong Wang <zhihong.wang@intel.com> Reviewed-by: Yuanhan Liu <yuanhan.liu@linux.intel.com> Tested-by: Lei Yao <lei.a.yao@intel.com>
DPDK is a set of libraries and drivers for fast packet processing. It supports many processor architectures and both FreeBSD and Linux. The DPDK uses the Open Source BSD license for the core libraries and drivers. The kernel components are GPLv2 licensed. Please check the doc directory for release notes, API documentation, and sample application information. For questions and usage discussions, subscribe to: users@dpdk.org Report bugs and issues to the development mailing list: dev@dpdk.org