On Mon, Apr 07, 2025 at 09:04:05AM +0200, David Marchand wrote: > Hello Bruce, > > On Tue, Apr 1, 2025 at 4:08 PM Bruce Richardson > <bruce.richard...@intel.com> wrote: > > > > 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? > > This seems useful, though I am not I would touch the existing options. > I would have gone with a simple -L option (taking the same kind of > input than -l but with new behavior), and not combine a flag with > existing options. >
That would be an easier patchset to do up. However, it would then mean that we have no less than 4 different ways to specify the cores to use: "-c", "-l", "-L", "--lcores" - and therefore need 4 different sets of parsing options for them, and more checks to ensure we have only one of the 4 specified in any run. That's why I chose the modifier option, and to try and consolidate the core setup a bit. However, if having a completely new option is preferred, I am happy enough to do up a different patchset for that. > I scanned through the series, not much to say. > Maybe add a unit test for new cmdline option. > Sure. Once it's decided what approach (if any) to take, I'll do up a new patchset, taking into account any relevant feedback on this set. /Bruce
