Re: git: 48bfd3597654 - main - Add nproc(1)

Mateusz Guzik <mjguzik@gmail.com> writes:

> On 2/14/23, Jan Beich <jbeich@freebsd.org> wrote:
>
>> Steffen Nurpmeso <steffen@sdaoden.eu> writes:
>>
>>>  |+     if (all_flag) {
>>>  |+             cpus = sysconf(_SC_NPROCESSORS_ONLN);
>>>
>>> is not compatible -- note i like the FreeBSD way better, and maybe
>>> someone should make a bug report even.
>>>
>>>   #?0|kent:$ getconf -a|grep NPROC
>>>   _NPROCESSORS_CONF                  8
>>>   _NPROCESSORS_ONLN                  4
>>
>> See also https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=230330
>>
>> $ cpuset -l 2-5 -- getconf -a | fgrep _NPROC
>> _NPROCESSORS_CONF: 8
>> _NPROCESSORS_ONLN: 4
>>
>
> As I mentioned previously in the thread, on linux these *don't* react
> to cpusets (or tasksets in linux parlance):
>
> $ getconf -a | grep _NPROC
> _NPROCESSORS_CONF                  4
> _NPROCESSORS_ONLN                  4
> $ taskset --cpu-list 0 getconf -a | grep _NPROC
> _NPROCESSORS_CONF                  4
> _NPROCESSORS_ONLN                  4
>
> consequently the patch proposed in the bz would introduce an
> incompatibility with linux

I've used kern.smp.cpus in old patches but found musl more practical.
_SC_NPROCESSORS_ONLN is often used as a default number of jobs.

glibc:
- /sys/devices/system/cpu/online
- /proc/stat
- sched_getaffinity

musl:
- sched_getaffinity

bionic:
- /sys/devices/system/cpu/online
- /proc/stat (Android < 7)