On Mon, Mar 24, 2025 at 05:30:26PM +0000, Bruce Richardson wrote: > Traditionally, DPDK has had a direct mapping of internal lcore-ids, to > the actual core numbers in use. With higher core count servers becoming > more prevalent the issue becomes one of increasing memory footprint when > using such a scheme, due to the need to have all arrays dimensioned for > all cores on the system, whether or not those cores are in use by the > app. > > Therefore, the decision was made in the past to not expand the > build-time RTE_MAX_LCORE value beyond 128. Instead, it was recommended > that users use the "--lcores" EAL parameter to take the high-numbered > cores they wish to use and map them to lcore-ids within the 0 - 128 > range. While this works, this is a little clunky as it means that > instead of just passing, for example, "-l 130-139", the user must > instead pass "--lcores 0@130,1@131,2@132,3@133,...." > > This patchset attempts to simplify the situation by adding a new flag to > do this mapping automatically. To use cores 130-139 and map them to ids > 0-9 internally, the EAL args now become: "-l 130-139 --map-lcore-ids", > or using the shorter "-M" version of the flag: "-Ml 130-139". > > Adding this new parameter required some rework of the existing arg > parsing code, because in current DPDK the args are parsed and checked in > the order they appear on the commandline. This means that using the > example above, the core parameter 130-139 will be rejected immediately > before the "map-lcore-ids" parameter is seen. To work around this, the > core (and service core) parameters are not parsed when seen, instead > they are only saved off and parsed after all arguments are parsed. The > "-l" and "-c" parameters are converted into "--lcores" arguments, so all > assigning of lcore ids is done there in all cases. > > RFC->v2: > * converted printf to DEBUG log > * added "-M" as shorter version of flag > * added documentation > * renamed internal API that was changed to avoid any potential hidden > runtime issues. > > Bruce Richardson (3): > eal: centralize core parameter parsing > eal: convert core masks and lists to core sets > eal: allow automatic mapping of high lcore ids > Ping for review.
At a high level, does this feature seem useful to users? /Bruce
