Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH] smp: Add bootcpus parameter to boot subset of CPUs | Date | Tue, 03 Nov 2020 23:10:06 +0100 |
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On Fri, Oct 30 2020 at 17:45, Sudeep Holla wrote: > On Thu, Oct 29, 2020 at 02:37:06PM -0700, Elliot Berman wrote: >> In the case where commercial device is using feature for thermal, device >> should boot multiple small cores. Booting only one core means we would not >> be able to use all possible cores to maximum extent possible in this thermal >> case. > > I understood that point. But you haven't responded on my logical vs physical > number argument. I am clearly NACKing this patch as is for just usage of > logical CPU IDs in the command line while your intention is to control > the physical CPUs. So once again, NACK for that reason.
Correct. And no, we are not going to add a command line option to select physical CPU ids.
There are two ways to solve that:
1) The firmware can tell the kernel whether a CPU should be brought up or not, e.g. by failing the bootup request.
2) The kernel has a way to figure out the current thermal and/or power budget early in the boot process and sorts out which and how many CPUs fit into that limit.
Thanks,
tglx
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