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SubjectRE: Linux 2.4.19ac3rc3 on IBM x330/x340 SMP - "ps" time skew
Date
> On Wed, 2002-07-31 at 13:59, David Luyer wrote:
> > printf("%d\n", sysconf(_SC_NPROCESSORS_CONF));
> > }
> > luyer@praxis8:~$ ./cpus
> > 4
> > luyer@praxis8:~$ grep 'processor ' /proc/cpuinfo
> > processor : 0
> > processor : 1
>
> In which case I suggest you file a glibc bug. sysconf looks
> at the /proc stuff as I understand it

Great, got it, thanks: sysconf(_SC_NPROCESSORS_CONF) parses
/proc/cpuinfo
using a simple parser:

#ifndef GET_NPROCS_PARSER
# define GET_NPROCS_PARSER(FP, BUFFER, RESULT)
\
do
\
{
\
(RESULT) = 0;
\
/* Read all lines and count the lines starting with the string
\
"processor". We don't have to fear extremely long lines since
\
the kernel will not generate them. 8192 bytes are really
\
enough. */
\
while (fgets_unlocked (BUFFER, sizeof (BUFFER), FP) != NULL)
\
if (strncmp (BUFFER, "processor", 9) == 0)
\
++(RESULT);
\
}
\
while (0)
#endif
It's being tricked by this:

luyer@praxis8:~$ cat /proc/cpuinfo | grep '^processor'
processor : 0
processor id : 0
processor : 1
processor id : 0
The "processor id" line, only present with SMP enabled, is being counted
as a processor.

David.

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