Re: per-thread rusage

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 4 Apr 2007 11:10:50 -0700
William Lee Irwin III <wli@holomorphy.com> wrote:

> On Wed, 4 Apr 2007 10:29:31 -0700 William Lee Irwin III <wli@holomorphy.com> wrote:
> >> It is not now possible for a thread to retrieve its own rusage in
> >> isolation. Its rusage is nowhere exposed without being intermixed with
> >> that of its sibling threads. This patch adds support for an
> >> RUSAGE_THREAD who argument that returns rusage for only the desired
> >> thread.
> 
> On Wed, Apr 04, 2007 at 07:48:29PM +0200, Eric Dumazet wrote:
> > Please check mm, because we now return ru_inblock and ru_oublock as well.
> > r->ru_inblock = task_io_get_inblock(p);
> > r->ru_oublock = task_io_get_oublock(p);
> 
> Respun vs. 2.6.21-rc5-mm4, still untested. Also...
> 
> Signed-off-by: William Irwin <bill.irwin@oracle.com>
> 
> 
> -- wli
> 
> 
> Index: mm-2.6.21-rc5-4/include/linux/resource.h
> ===================================================================
> --- mm-2.6.21-rc5-4.orig/include/linux/resource.h	2007-04-03 23:31:19.000000000 -0700
> +++ mm-2.6.21-rc5-4/include/linux/resource.h	2007-04-04 13:08:47.000000000 -0700
> @@ -18,7 +18,8 @@
>   */
>  #define	RUSAGE_SELF	0
>  #define	RUSAGE_CHILDREN	(-1)
> -#define RUSAGE_BOTH	(-2)		/* sys_wait4() uses this */
> +#define RUSAGE_THREAD	(-2)
> +#define RUSAGE_BOTH	(-3)		/* sys_wait4() uses this */
>  
>  struct	rusage {
>  	struct timeval ru_utime;	/* user time used */
> Index: mm-2.6.21-rc5-4/kernel/sys.c
> ===================================================================
> --- mm-2.6.21-rc5-4.orig/kernel/sys.c	2007-04-03 23:33:27.000000000 -0700
> +++ mm-2.6.21-rc5-4/kernel/sys.c	2007-04-04 13:11:17.000000000 -0700
> @@ -2074,6 +2074,16 @@
>  	}
>  
>  	switch (who) {
> +		case RUSAGE_THREAD:
> +			utime = p->utime;
> +			stime = p->stime;
> +			r->ru_nvcsw = p->nvcsw;
> +			r->ru_nivcsw = p->nivcsw;
> +			r->ru_minflt = p->min_flt;
> +			r->ru_majflt = p->maj_flt;
> +			r->ru_inblock = task_io_get_inblock(p);
> +			r->ru_oublock = task_io_get_oublock(p);
> +			break;
>  		case RUSAGE_BOTH:
>  		case RUSAGE_CHILDREN:
>  			utime = p->signal->cutime;
> @@ -2131,7 +2141,8 @@
>  
>  asmlinkage long sys_getrusage(int who, struct rusage __user *ru)
>  {
> -	if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN)
> +	if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN &&
> +						who != RUSAGE_THREAD)
>  		return -EINVAL;
>  	return getrusage(current, who, ru);
>  }

Seems sane.  Could we please get it tested and get a full description in
place?  Something which provides enough detail for the manpage maintainers.

Also, a quick comparison between Linux's RUSAGE_THREAD and $other-os's
implementations would reduce the possibility of silly, cast-in-stone
incompatabilities.