On Thu, Sep 14, 2017 at 10:42:52AM +0530, Nikunj A Dadhania wrote: > David Gibson <da...@gibson.dropbear.id.au> writes: > > > On Mon, Sep 11, 2017 at 10:40:10AM +0530, Nikunj A Dadhania wrote: > >> David Gibson <da...@gibson.dropbear.id.au> writes: > >> > >> > On Wed, Sep 06, 2017 at 01:57:48PM +0530, Nikunj A Dadhania wrote: > >> >> When the user does not provide the cpu topology, e.g. "-smp 4", machine > >> >> fails to > >> >> initialize 4 cpus. Compute the chip per cores depending on the number > >> >> of chips > >> >> and smt threads. > >> >> > >> >> Signed-off-by: Nikunj A Dadhania <nik...@linux.vnet.ibm.com> > >> > > >> > I don't understand why simply treating smp_cores as cores per chip is > >> > wrong. > >> > >> We do not have SMT support and when "-smp 4" is passed, smp_cores is > >> always set to 1. So only once core with one thread finally show up in > >> the guest. Moreover, I see spapr too doing similar thing in > >> spapr_init_cpus() with boot_cores_nr. > > > > I'm ok with adding an error if smp_threads > 1, since that won't > > work. Breaking the identity that smp_cores is the number of cores per > > socket (which should correspond to one chip) is not ok, though. > > > > I think you're misinterpreting the boot_cores_nr stuff - that's just > > about translating the number of initially online vcpus into a number > > of initially online cores. > > I thought, I am doing the same here for PowerNV, number of online cores > is equal to initial online vcpus / threads per core > > int boot_cores_nr = smp_cpus / smp_threads; > > Only difference that I see in PowerNV is that we have multiple chips > (max 2, at the moment) > > cores_per_chip = smp_cpus / (smp_threads * pnv->num_chips);
This doesn't make sense to me. Cores per chip should *always* equal
smp_cores, you shouldn't need another calculation for it.
> And in case user has provided sane smp_cores, we use it.
If smp_cores isn't sane, you should simply reject it, not try to fix
it. That's just asking for confusion.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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