From: Arthur Miller <arthur.miller@live.com>
To: Campbell Barton <ideasman42@gmail.com>
Cc: emacs-devel@gnu.org
Subject: Re: [PATCH] support for accessing CPU/core count (processor-count)
Date: Mon, 11 Oct 2021 10:01:40 +0200 [thread overview]
Message-ID: <AM9PR09MB49772E2EC8EE6AC320BAABA196B59@AM9PR09MB4977.eurprd09.prod.outlook.com> (raw)
In-Reply-To: <a3cc3806-f491-6c9f-d969-1a357f75f355@gmail.com> (Campbell Barton's message of "Mon, 11 Oct 2021 09:58:05 +1100")
Campbell Barton <ideasman42@gmail.com> writes:
> 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.
But then complete it :). I don't have openbsd installed.
> Also, this is not simply a call to an external process (executable-find "nproc")
> has some additional overhead.
You can skip that search if you want; it was just to be on the safe side. That
overhead is not importnat. As I wrote to Omar, you will probably ask for number
of cpu's in some eval-after-load or similar, not in some performance critical
code.
> 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.
nproc.c has already sorted all that for you; so you can just call the process
instead of doing it all over.
>> 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).
Why does os threads matter if you can't access them. Or you mean "logical cores"
a.k.a "hyperthreading"?
next prev parent reply other threads:[~2021-10-11 8:01 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-10 0:02 [PATCH] support for accessing CPU/core count (processor-count) Campbell Barton
2021-10-10 7:54 ` Omar Polo
2021-10-10 9:38 ` Arthur Miller
2021-10-10 9:43 ` Omar Polo
2021-10-10 10:52 ` Arthur Miller
2021-10-10 12:07 ` Omar Polo
2021-10-10 16:48 ` Arthur Miller
2021-10-10 18:17 ` Omar Polo
2021-10-10 19:45 ` Arthur Miller
2021-10-10 21:04 ` Omar Polo
2021-10-11 8:15 ` Arthur Miller
2021-10-11 8:20 ` Arthur Miller
2021-10-11 8:23 ` Omar Polo
2021-10-11 15:55 ` Arthur Miller
2021-10-10 21:32 ` Andreas Schwab
2021-10-11 8:03 ` Arthur Miller
2021-10-11 8:14 ` Andreas Schwab
2021-10-11 15:53 ` Arthur Miller
2021-10-11 16:49 ` Andreas Schwab
2021-10-11 17:14 ` Arthur Miller
2021-10-10 10:13 ` Campbell Barton
2021-10-10 10:38 ` Andreas Schwab
2021-10-10 11:21 ` Arthur Miller
2021-10-10 11:57 ` Andreas Schwab
2021-10-10 16:35 ` Arthur Miller
2021-10-10 17:27 ` Andreas Schwab
2021-10-10 18:13 ` Arthur Miller
2021-10-10 19:16 ` Stefan Monnier
2021-10-10 19:50 ` Arthur Miller
2021-10-10 22:58 ` Campbell Barton
2021-10-11 8:01 ` Arthur Miller [this message]
2021-10-10 12:21 ` Stefan Kangas
2021-10-10 16:03 ` Omar Polo
2021-10-10 21:11 ` Paul Eggert
2021-10-10 21:16 ` Omar Polo
2021-10-11 17:17 ` Arthur Miller
2021-10-10 10:50 ` Andy Moreton
2021-10-10 11:21 ` Arthur Miller
2021-10-10 12:09 ` Stefan Kangas
2021-10-10 22:43 ` Campbell Barton
2021-10-11 1:34 ` Po Lu
2021-10-11 1:51 ` Campbell Barton
2021-10-11 3:04 ` Po Lu
2021-10-11 4:01 ` Campbell Barton
2021-10-11 8:20 ` Lars Ingebrigtsen
2021-10-11 13:00 ` Eli Zaretskii
2021-10-11 15:12 ` Stefan Monnier
2021-10-11 16:07 ` Eli Zaretskii
2021-10-11 21:14 ` Andy Moreton
2021-10-11 22:13 ` Ken Brown
2021-10-12 2:27 ` Eli Zaretskii
2021-10-12 10:39 ` Lars Ingebrigtsen
2021-10-12 14:09 ` Eli Zaretskii
2021-10-12 19:58 ` Paul Eggert
2021-10-13 2:24 ` Eli Zaretskii
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