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    "msgid": "<>",
    "date": "2020-07-07T05:07:07",
    "name": "[v6,0/2] introduce asynchronous data path for vhost",
    "submitter": {
        "id": 1781,
        "url": "",
        "name": "Patrick Fu",
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            "id": 10832,
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            "date": "2020-07-07T05:07:07",
            "name": "introduce asynchronous data path for vhost",
            "version": 6,
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        "Subject": "[dpdk-dev] [PATCH v6 0/2] introduce asynchronous data path for vhost",
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        "Date": "Tue,  7 Jul 2020 13:07:07 +0800",
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    "content": "From: Patrick Fu <>\n\nPerforming large memory copies usually takes up a major part of CPU\ncycles and becomes the hot spot in vhost-user enqueue operation. To\noffload expensive memory operations from the CPU, this patch set\nproposes to leverage DMA engines, e.g., I/OAT, a DMA engine in the\nIntel's processor, to accelerate large copies.\n\nLarge copies are offloaded from the CPU to the DMA in an asynchronous\nmanner. The CPU just submits copy jobs to the DMA but without waiting\nfor its copy completion. Thus, there is no CPU intervention during\ndata transfer; we can save precious CPU cycles and improve the overall\nthroughput for vhost-user based applications, like OVS. During packet\ntransmission, it offloads large copies to the DMA and performs small\ncopies by the CPU, due to startup overheads associated with the DMA.\n\nThis patch set construct a general framework that applications can\nleverage to attach DMA channels with vhost-user transmit queues. Four\nnew RTE APIs are introduced to vhost library for applications to\nregister and use the asynchronous data path. In addition, two new DMA\noperation callbacks are defined, by which vhost-user asynchronous data\npath can interact with DMA hardware. Currently only enqueue operation\nfor split queue is implemented, but the framework is flexible to extend\nsupport for packed queue.\n\nv2:\nupdate meson file for new header file\nupdate to include new APIs\nrename async APIs/structures to be prefixed with \"rte_vhost\"\nrename some variables/structures for readibility\ncorrect minor typo in comments/license statements\nrefine memory allocation logic for vq internal buffer\nadd error message printing in some failure cases\ncheck inflight async packets in unregistration API call\nmark new APIs as experimental\n\nv3:\nuse atomic_xxx() functions in updating ring index\nfix a bug in async enqueue failure handling\n\nv4:\npart of the fix intended in v3 patch was missed, this patch\nadds all thoes fixes\n\nv5:\nminor changes on some function/variable names\nreset CPU batch copy packet count when async enqueue error\noccurs\ndisable virtio log feature in async copy mode\nminor optimization on async shadow index flush\n\nv6:\nadd some background introduction in the commit message\n\nPatrick Fu (2):\n  vhost: introduce async enqueue registration API\n  vhost: introduce async enqueue for split ring\n\n lib/librte_vhost/Makefile              |   2 +-\n lib/librte_vhost/           |   2 +-\n lib/librte_vhost/rte_vhost.h           |   1 +\n lib/librte_vhost/rte_vhost_async.h     | 176 ++++++++\n lib/librte_vhost/ |   4 +\n lib/librte_vhost/socket.c              |  27 ++\n lib/librte_vhost/vhost.c               | 127 +++++-\n lib/librte_vhost/vhost.h               |  30 +-\n lib/librte_vhost/vhost_user.c          |  23 +-\n lib/librte_vhost/virtio_net.c          | 551 ++++++++++++++++++++++++-\n 10 files changed, 934 insertions(+), 9 deletions(-)\n create mode 100644 lib/librte_vhost/rte_vhost_async.h"