On Mon, Jul 05, 2021 at 01:12:54PM +0200, Morten Brørup wrote: > > From: dev [mailto:dev-boun...@dpdk.org] On Behalf Of Bruce Richardson > > Sent: Monday, 5 July 2021 12.53 > > > > On Sun, Jul 04, 2021 at 03:00:30PM +0530, Jerin Jacob wrote: > > > On Fri, Jul 2, 2021 at 6:51 PM Chengwen Feng > > <fengcheng...@huawei.com> wrote: > > > > > > > > + > > > > +/** > > > > + * The data structure associated with each DMA device. > > > > + */ > > > > +struct rte_dmadev { > > > > + /**< Enqueue a copy operation onto the DMA device. */ > > > > + dmadev_copy_t copy; > > > > + /**< Enqueue a scatter list copy operation onto the DMA > > device. */ > > > > + dmadev_copy_sg_t copy_sg; > > > > + /**< Enqueue a fill operation onto the DMA device. */ > > > > + dmadev_fill_t fill; > > > > + /**< Enqueue a scatter list fill operation onto the DMA > > device. */ > > > > + dmadev_fill_sg_t fill_sg; > > > > + /**< Add a fence to force ordering between operations. */ > > > > + dmadev_fence_t fence; > > > > + /**< Trigger hardware to begin performing enqueued > > operations. */ > > > > + dmadev_perform_t perform; > > > > + /**< Returns the number of operations that successful > > completed. */ > > > > + dmadev_completed_t completed; > > > > + /**< Returns the number of operations that failed to > > complete. */ > > > > + dmadev_completed_fails_t completed_fails; > > > > > > We need to limit fastpath items in 1 CL > > > > > > > I don't think that is going to be possible. I also would like to see > > numbers to check if we benefit much from having these fastpath ops > > separate > > from the regular ops. > > The fastpath ops may not fit into 1 cache line, but it is a good design > practice to separate hot data from cold data, and I do consider the fastpath > function pointers hot and configuration function pointers cold. > > The important point is keeping all the fastpath ops (of a dmadevice) together > and spanning as few cache lines as possible. > > Configuration ops and other slow data may follow in the same structure; that > should make no performance difference. It might make a difference for memory > consumption if the other data are very large and not dynamically allocated, > as we are discussing regarding ethdev. >
Yes, I agree if it can be done, it should be.
