Thank you, Brice! I'm testing it on a Lenovo P1 laptop with an i7-12800H CPU with 6P + 8E. --cpukinds option solves the problem for me:-)
hwloc-calc --cpukind 1 all BTW, Intel's patches to improve Linux scheduling on hybrid architectures were significantly improved this year and released recently in kernel version 6.6. https://www.phoronix.com/news/Intel-Hybrid-Cluster-Sched-v3 Jirka On Fri, Nov 24, 2023 at 9:19 AM Brice Goglin <brice.gog...@inria.fr> wrote: > > Le 24/11/2023 à 08:51, John Hearns a écrit : > > Good question. Maybe not an answer referring to hwloc. > > When managing a large NUMA machine, SGI UV, I ran the OS processes in > > a boot cpuset which was restricted to (AFAIR) the first 8 Cpus. > > On Intel architecures with E and P cores could we think of running OS > > on E cores only and having the batch system schedule compute tasks on > > P cores? > > > > That's certainly possible. Linux has things like isolcpus to force > isolate some cores away from the OS tasks, should work for these > platforms too (by the way, it's also for ARM big.LITTLE platforms > running Linux, including Apple M1, etc). > > However, keep in mind that splitting P+E CPUs is not like splitting NUMA > platforms: isolating NUMA node #0 on SGI left tons of cores available > for HPC tasks on NUMA nodes. Current P+E from Intel usually have more E > than P, and several models are even 2P+8E, that would be a lot of > E-cores for the OS and very few P-cores for real apps. Your idea would > apply better if we rather had 2E+8P but that's not the trend. > > Things might be more interesting with MeteorLake which (according to > > https://www.hardwaretimes.com/intel-14th-gen-meteor-lake-cpu-cores-almost-identical-to-13th-gen-its-a-tic/) > > has P+E as usual but also 2 "low-power E" on the side. There, you could > put the OS on those 2 Low-Power E. > > By the way, the Linux scheduler is supposed to get enhanced to > automatically find out which tasks to put on P and E core but they've > been discussing things for a long time and it's hard to know what's > actually working well already. > > Brice > > > _______________________________________________ > hwloc-users mailing list > hwloc-users@lists.open-mpi.org > https://lists.open-mpi.org/mailman/listinfo/hwloc-users -- -Jirka
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