Hi Jiayu, On 11/1/19 9:54 AM, Jiayu Hu wrote: > This patch introduces a new PMD for DMA accelerated vhost-user, which > provides basic functionality of packet reception and transmission. This > PMD leverages librte_vhost to handle vhost messages, but it implements > own vring's enqueue and dequeue operations. > > The PMD leverages DMA engines (e.g., I/OAT, a DMA engine in Intel's > processor), to accelerate large data movements in enqueue and dequeue > operations. Large copies are offloaded to the DMA in an asynchronous mode. > That is, the CPU just submits copy jobs to the DMA but without waiting > for its completion; there is no CPU intervention during data transfer. > Thus, we can save precious CPU cycles and improve the overall performance > for vhost-user based applications, like OVS. The PMD still uses the CPU to > performs small copies, due to startup overheads associated with the DMA. > > Note that the PMD is able to support various DMA engines to accelerate > data movements in enqueue and dequeue operations; currently the supported > DMA engine is I/OAT. The PMD just supports I/OAT acceleration in the > enqueue operation, and it still uses the CPU to perform all copies in > the dequeue operation. In addition, the PMD only supports the split ring. > > The DMA device used by a queue is assigned by users; for the queue > without assigning a DMA device, the PMD will use the CPU to perform > all copies for both enqueue and dequeue operations. Currently, the PMD > just supports I/OAT, and a queue can only use one I/OAT device, and an > I/OAT device can only be used by one queue at a time. > > The PMD has 4 parameters. > - iface: The parameter is used to specify a path to connect to a > front end device. > - queues: The parameter is used to specify the number of the queues > front end device has (Default is 1). > - client: The parameter is used to specify the vhost port working as > client mode or server mode (Default is server mode). > - dmas: This parameter is used to specify the assigned DMA device > of a queue. > > Here is an example. > $ ./testpmd -c f -n 4 \ > --vdev 'dma_vhost0,iface=/tmp/sock0,queues=1,dmas=txq0@00:04.0,client=0'
dma_vhost0 is not a good name, you have to mention it is net specific. Is there a tool to list available DMA engines? > > Signed-off-by: Jiayu Hu <jiayu...@intel.com> > --- > config/common_base | 2 + > config/common_linux | 1 + > drivers/Makefile | 2 +- > drivers/net/Makefile | 1 + > drivers/net/vhost_dma/Makefile | 31 + > drivers/net/vhost_dma/eth_vhost.c | 1495 > ++++++++++++++++++++ > drivers/net/vhost_dma/eth_vhost.h | 264 ++++ > drivers/net/vhost_dma/internal.h | 225 +++ > .../net/vhost_dma/rte_pmd_vhost_dma_version.map | 4 + > drivers/net/vhost_dma/virtio_net.c | 1234 ++++++++++++++++ > mk/rte.app.mk | 1 + > 11 files changed, 3259 insertions(+), 1 deletion(-) > create mode 100644 drivers/net/vhost_dma/Makefile > create mode 100644 drivers/net/vhost_dma/eth_vhost.c > create mode 100644 drivers/net/vhost_dma/eth_vhost.h > create mode 100644 drivers/net/vhost_dma/internal.h > create mode 100644 drivers/net/vhost_dma/rte_pmd_vhost_dma_version.map > create mode 100644 drivers/net/vhost_dma/virtio_net.c You need to add Meson support. More generally, I have been through the series and I'm not sure having a dedicated PMD driver for this is a good idea due to all the code duplication it implies. I understand it has been done this way to avoid impacting the pure SW datapath implementation. But I'm sure the series could be reduced to a few hundred of lines if it was integrated in vhost-user library. Moreover, your series does not support packed ring, so it means even more code would need to be duplicated in the end. What do you think? Thanks, Maxime
