Re: [PATCH 7/9] lib/cpumask: add num_{possible,present,active}_cpus_{eq,gt,le}

Dennis Zhou
2021-11-28T17:56:11Z

Hello,

On Sun, Nov 28, 2021 at 09:43:20AM -0800, Yury Norov wrote:
> On Sun, Nov 28, 2021 at 09:07:52AM -0800, Joe Perches wrote:
> > On Sat, 2021-11-27 at 19:57 -0800, Yury Norov wrote:
> > > Add num_{possible,present,active}_cpus_{eq,gt,le} and replace num_*_cpus()
> > > with one of new functions where appropriate. This allows num_*_cpus_*()
> > > to return earlier depending on the condition.
> > []
> > > diff --git a/arch/arc/kernel/smp.c b/arch/arc/kernel/smp.c
> > []
> > > @@ -103,7 +103,7 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
> > > * if platform didn't set the present map already, do it now
> > > * boot cpu is set to present already by init/main.c
> > > */
> > > - if (num_present_cpus() <= 1)
> > > + if (num_present_cpus_le(2))
> > > init_cpu_present(cpu_possible_mask);
> >
> > ? is this supposed to be 2 or 1
>
> X <= 1 is the equivalent of X < 2.
>
> > > diff --git a/drivers/cpufreq/pcc-cpufreq.c b/drivers/cpufreq/pcc-cpufreq.c
> > []
> > > @@ -593,7 +593,7 @@ static int __init pcc_cpufreq_init(void)
> > > return ret;
> > > }
> > >
> > > - if (num_present_cpus() > 4) {
> > > + if (num_present_cpus_gt(4)) {
> > > pcc_cpufreq_driver.flags |= CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING;
> > > pr_err("%s: Too many CPUs, dynamic performance scaling disabled\n",
> > > __func__);
> >
> > It looks as if the present variants should be using the same values
> > so the _le test above with 1 changed to 2 looks odd.
>

I think the confusion comes from le meaning less than rather than lt.
Given the general convention of: lt (<), le (<=), eg (=), ge (>=),
gt (>), I'd consider renaming your le to lt.

Thanks,
Dennis