> From: dev [mailto:dev-boun...@dpdk.org] On Behalf Of Thomas Monjalon > Sent: Tuesday, 15 June 2021 08.48 > > 14/06/2021 17:48, Morten Brørup: > > > From: dev [mailto:dev-boun...@dpdk.org] On Behalf Of Thomas > Monjalon > > It would be much simpler to just increase RTE_MAX_ETHPORTS to > something big enough to hold a sufficiently large array. And possibly > add an rte_max_ethports variable to indicate the number of populated > entries in the array, for use when iterating over the array. > > > > Can we come up with another example than RTE_MAX_ETHPORTS where this > library provides a better benefit? > > What is big enough? > Is 640KB enough for RAM? ;)
Good point! I think we agree that: - The cost of this library is some added complexity, i.e. working with a dynamically sized array through a library instead of just indexing into a compile time fixed size array. - The main benefit of this library is saving some RAM (and still allowing a potentially very high number of ports.) My point was: The amount of RAM we are saving is a key parameter for the cost/benefit analysis. And since I don't think the rte_eth_devices[] array uses a significant amount of memory, I was asking for some other array using more memory, where the cost/benefit analysis would come out more advantageous to your proposed parray library. > > When dealing with microservices switching, the numbers can increase > very fast. Yes, I strongly supported increasing the port_id type from 8 to 16 bits for this reason, when it was discussed at the DPDK Userspace a few years ago in Dublin. And with large RTE_MAX_QUEUES_PER_PORT values, the rte_eth_dev structure uses quite a lot of space for the rx/tx callback arrays. But the memory usage of rte_eth_devices[] is still relatively insignificant in a system wide context. If main purpose is to optimize the rte_eth_devices[] array, I think there are better alternatives than this library. Bruce and Konstantin already threw a few ideas on the table.
