From: Roland McGrath <roland@redhat.com>
After my cleanup of the rusage semantics was so quickly taken in by Andrew
and Linus without comment, I wonder if I should not have tried to be so
accommodating of potential objections as I was. :-)
In my original posting, I solicited comment on whether introducing
RUSAGE_GROUP as distinct from RUSAGE_SELF was warranted. Note that we've
now changed the behavior of the times system call when using CLONE_THREAD,
so changing getrusage RUSAGE_SELF to match would be consistent. I think
that changing the meaning of the old RUSAGE_SELF value is preferable to
introducing the new value for the proper POSIX getrusage behavior. This
patch against Linus's current tree dumps RUSAGE_GROUP and makes RUSAGE_SELF
have the fixed behavior.
If there is interest in having a new explicit interface to sample a single
thread's stats alone, then I think that would be better done by introducing
a new value for RUSAGE_THREAD. This is trivial to implement, but I won't
offer patches bloating the interface if noone is actually interested in
using it.
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/include/linux/resource.h | 1 -
25-akpm/kernel/sys.c | 15 +++------------
2 files changed, 3 insertions(+), 13 deletions(-)
diff -puN include/linux/resource.h~nix-rusage_group include/linux/resource.h
--- 25/include/linux/resource.h~nix-rusage_group 2004-09-02 21:04:54.644015152 -0700
+++ 25-akpm/include/linux/resource.h 2004-09-02 21:04:54.649014392 -0700
@@ -17,7 +17,6 @@
#define RUSAGE_SELF 0
#define RUSAGE_CHILDREN (-1)
#define RUSAGE_BOTH (-2) /* sys_wait4() uses this */
-#define RUSAGE_GROUP (-3) /* thread group sum + dead threads */
struct rusage {
struct timeval ru_utime; /* user time used */
diff -puN kernel/sys.c~nix-rusage_group kernel/sys.c
--- 25/kernel/sys.c~nix-rusage_group 2004-09-02 21:04:54.646014848 -0700
+++ 25-akpm/kernel/sys.c 2004-09-02 21:04:54.651014088 -0700
@@ -1582,7 +1582,7 @@ asmlinkage long sys_setrlimit(unsigned i
* This expects to be called with tasklist_lock read-locked or better,
* and the siglock not locked. It may momentarily take the siglock.
*
- * When sampling multiple threads for RUSAGE_GROUP, under SMP we might have
+ * When sampling multiple threads for RUSAGE_SELF, under SMP we might have
* races with threads incrementing their own counters. But since word
* reads are atomic, we either get new values or old values and we don't
* care which for the sums. We always take the siglock to protect reading
@@ -1603,14 +1603,6 @@ void k_getrusage(struct task_struct *p,
return;
switch (who) {
- case RUSAGE_SELF:
- jiffies_to_timeval(p->utime, &r->ru_utime);
- jiffies_to_timeval(p->stime, &r->ru_stime);
- r->ru_nvcsw = p->nvcsw;
- r->ru_nivcsw = p->nivcsw;
- r->ru_minflt = p->min_flt;
- r->ru_majflt = p->maj_flt;
- break;
case RUSAGE_CHILDREN:
spin_lock_irqsave(&p->sighand->siglock, flags);
utime = p->signal->cutime;
@@ -1623,7 +1615,7 @@ void k_getrusage(struct task_struct *p,
jiffies_to_timeval(utime, &r->ru_utime);
jiffies_to_timeval(stime, &r->ru_stime);
break;
- case RUSAGE_GROUP:
+ case RUSAGE_SELF:
spin_lock_irqsave(&p->sighand->siglock, flags);
utime = stime = 0;
goto sum_group;
@@ -1672,8 +1664,7 @@ int getrusage(struct task_struct *p, int
asmlinkage long sys_getrusage(int who, struct rusage __user *ru)
{
- if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN
- && who != RUSAGE_GROUP)
+ if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN)
return -EINVAL;
return getrusage(current, who, ru);
}
_