Re: [PATCH] support for accessing CPU/core count (processor-count)

[Campbell Barton <ideasman42@gmail.com>]

On 10/11/21 06:50, Arthur Miller wrote:
> Stefan Monnier <monnier@iro.umontreal.ca> writes:
> 
>>> We seem to be talking past each other. I don't see why would want this as a C
>>> primitive.
>>
>> There are typically 2 reasons to use C:
>> - For speed
>> - To use someone else's code which is easily available from C but not
>>    from ELisp.
> 
> Of course, but I don't see any of those apply to this case :).

The Elisp version of this function posted was incomplete by comparison 
in that it didn't support OpenBSD's ncpuonline feature or HPUX.

Also, this is not simply a call to an external process (executable-find 
"nproc") has some additional overhead.

I don't see this so much a case of ELisp vs C, more a case of OS-level 
API's being more appropriate than searching around for commands and 
parsing their output.

> As I see nproc from core-utils is already doing suggested, and more than so, so
> it is just to call it :).
> 
> https://github.com/coreutils/gnulib/blob/master/lib/nproc.c
> 
> PS: it is not directly "a couple of lines" either as someone suggested :).

Right, it's quite involved, as mentioned in a previous reply, this seems 
more appropriate for detecting OS-level threads (not spawning new 
processes).