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Date: Thu, 28 Jun 2012 09:52:09 +0800
From: David Xu <listlog2011@gmail.com>
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To: Konstantin Belousov <kib@FreeBSD.org>
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Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org,
	src-committers@FreeBSD.org
Subject: Re: svn commit: r237660 - head/lib/libc/gen
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On 2012/6/28 4:32, Konstantin Belousov wrote:
> Author: kib
> Date: Wed Jun 27 20:32:45 2012
> New Revision: 237660
> URL: http://svn.freebsd.org/changeset/base/237660
>
> Log:
>    Optimize the handling of SC_NPROCESSORS_CONF, by using auxv AT_NCPU
>    value if present.
>
>    MFC after:	1 week
>
> Modified:
>    head/lib/libc/gen/sysconf.c
>
> Modified: head/lib/libc/gen/sysconf.c
> ==============================================================================
> --- head/lib/libc/gen/sysconf.c	Wed Jun 27 20:24:25 2012	(r237659)
> +++ head/lib/libc/gen/sysconf.c	Wed Jun 27 20:32:45 2012	(r237660)
> @@ -42,6 +42,7 @@ __FBSDID("$FreeBSD$");
>   #include<sys/resource.h>
>   #include<sys/socket.h>
>
> +#include<elf.h>
>   #include<errno.h>
>   #include<limits.h>
>   #include<paths.h>
> @@ -51,6 +52,7 @@ __FBSDID("$FreeBSD$");
>
>   #include "../stdlib/atexit.h"
>   #include "tzfile.h"		/* from ../../../contrib/tzcode/stdtime */
> +#include "libc_private.h"
>
>   #define	_PATH_ZONEINFO	TZDIR	/* from tzfile.h */
>
> @@ -585,6 +587,8 @@ yesno:
>
>   	case _SC_NPROCESSORS_CONF:
>   	case _SC_NPROCESSORS_ONLN:
> +		if (_elf_aux_info(AT_NCPUS,&value, sizeof(value)) == 0)
> +			return ((long)value);
>   		mib[0] = CTL_HW;
>   		mib[1] = HW_NCPU;
>   		break;
>
Will this make controlling the number of CPU online or CPU hotplug
be impossible on FreeBSD ?

Regards,
David Xu