Re: [Xen-devel] [PATCH 2/6] xen/sched: Use %*pb[l] instead of cpumask_scn{, list}printf()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 07/09/18 09:03, Jan Beulich wrote:
>>>> On 06.09.18 at 14:08, <andrew.cooper3@xxxxxxxxxx> wrote:
>> @@ -2059,11 +2058,10 @@ csched_dump_pcpu(const struct scheduler *ops, int 
>> cpu)
>>      spc = CSCHED_PCPU(cpu);
>>      runq = &spc->runq;
>>  
>> -    cpumask_scnprintf(cpustr, sizeof(cpustr), per_cpu(cpu_sibling_mask, 
>> cpu));
>> -    printk("CPU[%02d] nr_run=%d, sort=%d, sibling=%s, ",
>> -           cpu, spc->nr_runnable, spc->runq_sort_last, cpustr);
>> -    cpumask_scnprintf(cpustr, sizeof(cpustr), per_cpu(cpu_core_mask, cpu));
>> -    printk("core=%s\n", cpustr);
>> +    printk("CPU[%02d] nr_run=%d, sort=%d, sibling=%*pb, core=%*pb\n",
>> +           cpu, spc->nr_runnable, spc->runq_sort_last,
>> +           nr_cpu_ids, per_cpu(cpu_sibling_mask, cpu),
>> +           nr_cpu_ids, per_cpu(cpu_core_mask, cpu));
> Strictly speaking here and elsewhere you should wrap the CPU mask
> accesses in cpumask_bits().

Why? Its barely used, and is another example of a helper which only adds
to code volume.

> Then again I wonder whether a special
> case for CPU masks wouldn't be warranted, making it unnecessary for
> callers to pass in nr_cpu_ids explicitly.

The only way of special casing is to have a different custom %p
formatter.  All printing of cpu and nodemasks are in keyhandlers so I
don't think a custom case is going to be worth it.

~Andrew

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