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Re: [PATCH] xfstests: src/feature.c: print a number of online CPUs

To: Stanislav Kholmanskikh <stanislav.kholmanskikh@xxxxxxxxxx>
Subject: Re: [PATCH] xfstests: src/feature.c: print a number of online CPUs
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Thu, 24 Oct 2013 21:40:42 +1100
Cc: xfs@xxxxxxxxxxx, vasily.isaenko@xxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1382604998-11037-1-git-send-email-stanislav.kholmanskikh@xxxxxxxxxx>
References: <20131023213152.GP2797@dastard> <1382604998-11037-1-git-send-email-stanislav.kholmanskikh@xxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Thu, Oct 24, 2013 at 12:56:38PM +0400, Stanislav Kholmanskikh wrote:
> For this purpose we use sysconf() as it is the
> preferred platform neutral interface for getting this
> sort of information.
> 
> Based on Dave Chinner proposal.
> 
> Signed-off-by: Stanislav Kholmanskikh <stanislav.kholmanskikh@xxxxxxxxxx>
> ---
>  src/feature.c |   31 ++++++++++++++++++++++++++++---
>  1 files changed, 28 insertions(+), 3 deletions(-)
> 
> diff --git a/src/feature.c b/src/feature.c
> index 2619ca5..a3ce9b8 100644
> --- a/src/feature.c
> +++ b/src/feature.c
> @@ -30,6 +30,7 @@
>   * Return code: 0 is true, anything else is error/not supported
>   *
>   * Test for machine features
> + *   -o  report a number of online cpus
>   *   -s  report pagesize
>   *   -w  report bits per long
>   */
> @@ -39,6 +40,7 @@
>  #include <sys/quota.h>
>  #include <sys/resource.h>
>  #include <signal.h>
> +#include <unistd.h>
>  
>  #ifdef HAVE_XFS_XQM_H
>  #include <xfs/xqm.h>
> @@ -64,7 +66,7 @@ usage(void)
>       fprintf(stderr, "Usage: feature [-v] -<q|u|g|p|U|G|P> <filesystem>\n");
>       fprintf(stderr, "       feature [-v] -c <file>\n");
>       fprintf(stderr, "       feature [-v] -t <file>\n");
> -     fprintf(stderr, "       feature -s | -w\n");
> +     fprintf(stderr, "       feature -o | -s | -w\n");
>       exit(1);
>  }
>  
> @@ -212,9 +214,10 @@ main(int argc, char **argv)
>       int     uflag = 0;
>       int     Uflag = 0;
>       int     wflag = 0;
> +     int     oflag = 0;
>       char    *fs = NULL;
>  
> -     while ((c = getopt(argc, argv, "ctgGpPqsuUvw")) != EOF) {
> +     while ((c = getopt(argc, argv, "ctgGopPqsuUvw")) != EOF) {
>               switch (c) {
>               case 'c':
>                       cflag++;
> @@ -228,6 +231,9 @@ main(int argc, char **argv)
>               case 'G':
>                       Gflag++;
>                       break;
> +             case 'o':
> +                     oflag++;
> +                     break;
>               case 'p':
>                       pflag++;
>                       break;
> @@ -262,7 +268,7 @@ main(int argc, char **argv)
>               if (optind != argc-1)   /* need a device */
>                       usage();
>               fs = argv[argc-1];
> -     } else if (wflag || sflag) {
> +     } else if (wflag || sflag || oflag) {
>               if (optind != argc)
>                       usage();
>       } else 
> @@ -306,6 +312,25 @@ bozo!
>  #endif
>               exit(0);
>       }
> +     if (oflag) {
> +             long ncpus;
> +
> +#if defined(_SC_NPROCESSORS_ONLN)
> +             /* Linux */
> +             ncpus = sysconf(_SC_NPROCESSORS_ONLN);
> +#elif defined(_SC_NPROC_ONLN)
> +             /* IRIX */
> +             ncpus = sysconf(_SC_NPROC_ONLN);
> +#else
> +             ncpus = 0;
> +#endif
> +             if (ncpus == -1)
> +                     ncpus = 0;
> +
> +             printf("%ld\n", ncpus);

Actually, I'd say we shoul default to 1 cpu if we can't get the
number of CPUs. Clearly we have at least one if we can run this
code. :)

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx

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