On 12/14/2023 1:43 PM, Michael Baum wrote: > > On 12/14/2023 2:18 PM, Ferruh Yigit wrote: >> >> On 12/14/2023 10:58 AM, Michael Baum wrote: >>> Add support for a new item type "RTE_FLOW_ITEM_TYPE_RANDOM". >>> This item enables to match on some random value as a part of flow rule. >>> > > ... > >>> >>> +Item: ``RANDOM`` >>> +^^^^^^^^^^^^^^^^ >>> + >>> +Matches a random value. >>> + >>> +A random unsigned integer (at most 32-bit) is generated for each >>> +packet during flow rule processing, by either HW, SW or some external >>> source. >>> +Application can match on either exact value or range of values. >>> +This value is not based on the packet data/headers. >>> +Application shouldn't assume that this value is kept during the >>> +lifetime of the packet. >>> + >>> +- ``value``: Specific value to match. >>> + >> >> >> Hi Michael, >> >> What is the usecase for the 'random' flow item? > I can think about 2 different use cases: > 1. Sampling - when application wants to sample certain percentage of the > flow, it can match random value for getting it. > 2. Distribution - when application wants to distribute the traffic between > ports/queues, it can match all random value range with send to port/queue > actions. > >> >> Is it to match some kind of metadata generated by HW? > It can be generated by either HW, SW or some external source. > Each PMD supporting random item responds to have a generator for that. > >> Or is it a way to sampling traffic? > It can be both. The PMD can use random value generated by HW while user match > on it for sampling traffic. > >> >> And how random 'random' item is, is it configured/set in HW or random per >> packet? > From API perspective, it is pure random not packet oriented. Same packet can > get different values during the pipeline. > I mentioned it in documentation: > "This value is not based on the packet data/headers. > Application shouldn't assume that this value is kept during the lifetime of > the packet." >
Thanks Michael, for clarification. I was thinking if this can be used together with external (to DPDK) flow steering configuration. Like external tool can set values to match for specific pattern, tcp --> 100 udp --> 200 Later these values can be used by DPDK application and this filtering item. Can you please confirm this is not the "use case"/intention, if so we may need to rename the rte flow item. Also there will be driver implementation in this release, right?
