Re: [dpdk-dev] [RFC PATCH v2 0/7] heterogeneous computing library

["Wang, Haiyue" <haiyue.wang@intel.com>]

> -----Original Message-----
> From: Elena Agostini <eagostini@nvidia.com>
> Sent: Tuesday, September 7, 2021 00:11
> To: Jerin Jacob <jerinjacobk@gmail.com>
> Cc: Wang, Haiyue <haiyue.wang@intel.com>; NBU-Contact-Thomas Monjalon <thomas@monjalon.net>; Jerin
> Jacob <jerinj@marvell.com>; dpdk-dev <dev@dpdk.org>; Stephen Hemminger <stephen@networkplumber.org>;
> David Marchand <david.marchand@redhat.com>; Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>; Honnappa
> Nagarahalli <honnappa.nagarahalli@arm.com>; Yigit, Ferruh <ferruh.yigit@intel.com>; techboard@dpdk.org
> Subject: RE: [dpdk-dev] [RFC PATCH v2 0/7] heterogeneous computing library
> 
> 
> 


> > >
> > > I'd like to introduce (with a dedicated option) the memory API in
> > > testpmd to provide an example of how to TX/RX packets using device
> > memory.
> >
> > Not sure without embedding sideband communication mechanism how it
> > can notify to GPU and back to CPU. If you could share the example API
> > sequence that helps to us understand the level of coupling with testpmd.
> >
> 
> There is no need of communication mechanism here.
> Assuming there is not workload to process network packets (to not complicate
> things), the steps are:
> 1) Create a DPDK mempool with device external memory using the hcdev (or gpudev) library
> 2) Use that mempool to tx/rx/fwd packets
> 
> As an example, you look at my l2fwd-nv application here: https://github.com/NVIDIA/l2fwd-nv
> 

To enhance the 'rte_extmem_register' / 'rte_pktmbuf_pool_create_extbuf' ?

	if (l2fwd_mem_type == MEM_HOST_PINNED) {
		ext_mem.buf_ptr = rte_malloc("extmem", ext_mem.buf_len, 0);
		CUDA_CHECK(cudaHostRegister(ext_mem.buf_ptr, ext_mem.buf_len, cudaHostRegisterMapped));
		void *pDevice;
		CUDA_CHECK(cudaHostGetDevicePointer(&pDevice, ext_mem.buf_ptr, 0));
		if (pDevice != ext_mem.buf_ptr)
			rte_exit(EXIT_FAILURE, "GPU pointer does not match CPU pointer\n");
	} else {
		ext_mem.buf_iova = RTE_BAD_IOVA;
		CUDA_CHECK(cudaMalloc(&ext_mem.buf_ptr, ext_mem.buf_len));
		if (ext_mem.buf_ptr == NULL)
			rte_exit(EXIT_FAILURE, "Could not allocate GPU memory\n");

		unsigned int flag = 1;
		CUresult status = cuPointerSetAttribute(&flag, CU_POINTER_ATTRIBUTE_SYNC_MEMOPS, (CUdeviceptr)ext_mem.buf_ptr);
		if (CUDA_SUCCESS != status) {
			rte_exit(EXIT_FAILURE, "Could not set SYNC MEMOP attribute for GPU memory at %llx\n", (CUdeviceptr)ext_mem.buf_ptr);
		}
		ret = rte_extmem_register(ext_mem.buf_ptr, ext_mem.buf_len, NULL, ext_mem.buf_iova, GPU_PAGE_SIZE);
		if (ret)
			rte_exit(EXIT_FAILURE, "Could not register GPU memory\n");
	}
	ret = rte_dev_dma_map(rte_eth_devices[l2fwd_port_id].device, ext_mem.buf_ptr, ext_mem.buf_iova, ext_mem.buf_len);
	if (ret)
		rte_exit(EXIT_FAILURE, "Could not DMA map EXT memory\n");
	mpool_payload = rte_pktmbuf_pool_create_extbuf("payload_mpool", l2fwd_nb_mbufs,
											0, 0, ext_mem.elt_size, 
											rte_socket_id(), &ext_mem, 1);
	if (mpool_payload == NULL)
		rte_exit(EXIT_FAILURE, "Could not create EXT memory mempool\n");