Thanks, comment inline On 2021/7/29 17:15, Bruce Richardson wrote: > On Thu, Jul 29, 2021 at 09:26:31AM +0800, fengchengwen wrote: >> Thanks, inline comment >> >> On 2021/7/28 19:13, Bruce Richardson wrote: >>> On Tue, Jul 27, 2021 at 11:39:59AM +0800, Chengwen Feng wrote: >>>> This patch introduce 'dmadevice' which is a generic type of DMA >>>> device. >>>> >>>> The APIs of dmadev library exposes some generic operations which can >>>> enable configuration and I/O with the DMA devices. >>>> >>>> Signed-off-by: Chengwen Feng <fengcheng...@huawei.com> >>>> Acked-by: Bruce Richardson <bruce.richard...@intel.com> >>>> Acked-by: Morten Brørup <m...@smartsharesystems.com> >>>> --- >>> >>> Thanks for this. Before it gets merged, I believe it needs to be split >>> further into multiple patches (say 4 or so) rather than adding the whole >>> lib in one go. >>> >>> Normally, I believe the split would be something like: >>> * basic device structures and infrastructure e.g. alloc and release >>> functions >>> * device config functions (and structures to go along with them) >>> such as configure and queue_setup >>> * data plane functions >>> >> >> I will try for it >> Maybe one patch for public file, one for pmd header file, one for >> implementation, and last for doc. >> >>> Documentation would be included in each of the patches, rather than done as >>> a block at the end. >>> >>> Besides that, I have one small additional requests for the API. Based off >>> feedback for ioat driver, we added in the following function to that API, >>> and we probably need something similar in dmadev: >>> >>> rte_ioat_burst_capacity() >>> >>> For our implementation this returns the number of elements that can be >>> enqueued to the ring, at least for the current burst/batch of packets. We >>> did the API this way because there can be additional limits beyond ring >>> size on each individual burst beyond just the raw ring capacity, e.g. even >>> if there are 4k ring elements free, there may be limits on the max burst >>> size the hardware can do, or limits on the number of outstanding >>> batches etc. >>> >>> Therefore can I request the addition of rte_dmadev_burst_capacity() [or >>> something similarly named] to the basic dmadev API set. For most hardware, >>> I think this will likely be the remaining free ring size, but I don't >>> believe the API should commit to that. The use case it was added for was to >>> enable an application which needs to do a multi-copy operation to check >>> that all copies can fit or not before enqueuing the first one. This is >>> important for hardware that doesn't have scatter-gather list support. >> >> Remaining capacity can be inferred by ring_idx which return from enqueue and >> dequeue APIs. >> So I don't think this API needs to be added. >> > > Yes, the app can always track it itself, but I still see value in adding > this API. However, so long as you are open to having it added later, it > doesn't matter if it's not present in the first versions of this API merged > in.
Got it, I think we could discuss later when we adapt more drivers. > > /Bruce > . >
