On Thu, Feb 13, 2020 at 5:20 PM Doherty, Declan <declan.dohe...@intel.com> wrote: > > On 07/02/2020 2:18 PM, Jerin Jacob wrote: > > On Fri, Feb 7, 2020 at 6:08 PM Coyle, David <david.co...@intel.com> wrote: > >> > >> Hi Jerin, see below > > > > Hi David, > > > >>> > >>> On Thu, Feb 6, 2020 at 10:01 PM Coyle, David <david.co...@intel.com> > >>> wrote: > >>> > > > >>> > >>> There is a risk in drafting API that meant for HW without any HW exists. > >>> Because there could be inefficiency on the metadata and fast path API for > >>> both models. > >>> For example, In the case of CPU based scheme, it will be pure overhead > >>> emulate the "queue"(the enqueue and dequeue) for the sake of abstraction > >>> where CPU works better in the synchronous model and I have doubt that the > >>> session-based scheme will work for HW or not as both difference HW needs > >>> to work hand in hand(IOMMU aspects for two PCI device) > >> > >> [DC] I understand what you are saying about the overhead of emulating the > >> "sw queue" but this same model is already used in many of the existing > >> device PMDs. > >> In the case of SW devices, such as AESNI-MB or NULL for crypto or zlib for > >> compression, the enqueue/dequeue in the PMD is emulated through an > >> rte_ring which is very efficient. > >> The accelerator API will use the existing device PMDs so keeping the same > >> model seems like a sensible approach. > > > > In this release, we added CPU crypto support in cryptodev to support > > the synchronous model to fix the overhead. > > > >> > >> From an application's point of view, this abstraction of the underlying > >> device type is important for usability and maintainability - the > >> application doesn't need to know > >> the device type as such and therefore doesn't need to make different API > >> calls. > >> > >> The enqueue/dequeue type API was also used with QAT in mind. While QAT HW > >> doesn't support these xform chains at the moment, it could potentially do > >> so in the future. > >> As a side note, as part of the work of adding the accelerator API, the QAT > >> PMD will be updated to support the DOCSIS Crypto-CRC accelerator xform > >> chain, where the Crypto > >> is done on QAT HW and the CRC will be done in SW, most likely through a > >> call to the optimized rte_net_crc library. This will give a consistent API > >> for the DOCSIS-MAC data-plane > >> pipeline prototype we have developed, which uses both AESNI-MB and QAT for > >> benchmarks. > >> > >> We will take your feedback on the enqueue/dequeue approach for SW devices > >> into consideration though during development. > >> > >> Finally, I'm unsure what you mean by this line: > >> > >> "I have doubt that the session-based scheme will work for HW or > >> not as both difference HW needs to work hand in hand(IOMMU aspects for > >> two PCI device)" > >> > >> What do mean by different HW working "hand in hand" and "two PCI device"? > >> The intention is that 1 HW device (or it's PMD) would have to support the > >> accel xform chain > > > > I was thinking, it will be N PCIe devices that create the chain. Each > > distinct PCI device does the fixed-function and chains them together. > > > > The case we were looking at is more focused on a single discrete > (multi-function) device (from the perspective of the host) providing a > number of transforms (operations) in a single pass rather than the case > of N discrete hardware devices (from the perspective of the host) > chained together to achieve the same transforms set.
Yes. For multifunction PCI device, it will be easy as it has a single DMA stream aka single IOMMU context. DMA between Two discrete hardware devices may need additional semantics. > > > > I do understand the usage of QAT HW and CRC in SW. > > So If I understand it correctly, in rte_security, we are combining > > rte_ethdev and rte_cryptodev. With this spec, we are trying to > > combine, > > rte_cryptodev and rte_compressdev. So it looks good to me. My only > > remaining concern is the name of this API, accelerator too generic > > name. IMO, like rte_security, we may need to give more meaningful name > > for the use case where crytodev and compressdev can work together. > > >
