Date: Tue, 14 Feb 2023 01:21:29 +0100 From: Jan Beich <jbeich@FreeBSD.org> To: Mateusz Guzik <mjguzik@gmail.com> Cc: src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: 48bfd3597654 - main - Add nproc(1) Message-ID: <ttzp-3xme-wny@FreeBSD.org> In-Reply-To: <CAGudoHForbPDR-vzXjKcDJTv=VTj-p=icbfZ2rogPy31r_jL4A@mail.gmail.com> (Mateusz Guzik's message of "Tue, 14 Feb 2023 00:58:41 %2B0100") References: <202302081947.318Jlbt6052826@gitrepo.freebsd.org> <20230208202736.L7hpB%steffen__28609.3347867549$1675888077$gmane$org@sdaoden.eu> <1qmt-6s1w-wny@FreeBSD.org> <CAGudoHForbPDR-vzXjKcDJTv=VTj-p=icbfZ2rogPy31r_jL4A@mail.gmail.com>
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Mateusz Guzik <mjguzik@gmail.com> writes:
> On 2/14/23, Jan Beich <jbeich@freebsd.org> wrote:
>
>> Steffen Nurpmeso <steffen@sdaoden.eu> writes:
>>
>>> |+ if (all_flag) {
>>> |+ cpus = sysconf(_SC_NPROCESSORS_ONLN);
>>>
>>> is not compatible -- note i like the FreeBSD way better, and maybe
>>> someone should make a bug report even.
>>>
>>> #?0|kent:$ 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)
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