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From: Jeff Dike <jdike@addtoit.com>
To: Stanislav Meduna <stano@meduna.org>
Cc: user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [uml-devel] sysconf(_SC_NPROCESSORS_CONF) returning zero
Date: Mon, 4 Aug 2008 16:33:20 -0400	[thread overview]
Message-ID: <20080804203319.GA14732@c2.user-mode-linux.org> (raw)
In-Reply-To: <48970AEC.6020503@meduna.org>

On Mon, Aug 04, 2008 at 03:58:04PM +0200, Stanislav Meduna wrote:
> Hi,
> 
> the following program
> 
> ===
> #include <unistd.h>
> #include <stdio.h>
> 
> main()
> {
>    printf("Number of processors: %d\n", sysconf(_SC_NPROCESSORS_CONF));
> }
> ===
> 
> produces
> 
>    Number of processors: 0
> 
> on my system.

Works here...

[root@uml-test ~]# cc -o ncpus ncpus.c 
[root@uml-test ~]# ./ncpus 
Number of processors: 1

sysconf seems to be looking at /proc/stat, which looks like this here:

	cpu  80 0 157 12771 984 0 0 0 0
	cpu0 80 0 157 12771 984 0 0 0 0
	intr 15259 12519 0 75 0 2590 0 0 0 0 0 0 74 0 0 1
	ctxt 8081
	btime 1217881784
	processes 1144
	procs_running 3
	procs_blocked 0

I'd guess it's looking at the cpu0 (and cpu<n>) lines.

    	       	       	  Jeff

-- 
Work email - jdike at linux dot intel dot com

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  reply	other threads:[~2008-08-04 20:33 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-08-04 13:58 [uml-devel] sysconf(_SC_NPROCESSORS_CONF) returning zero Stanislav Meduna
2008-08-04 20:33 ` Jeff Dike [this message]
2008-08-04 20:59   ` Stanislav Meduna
2008-08-04 21:47     ` Jeff Dike
2008-08-04 22:06       ` Stanislav Meduna
2008-08-04 22:07       ` Ingo van Lil

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