From: Peter Chubb <peterc@gelato.unsw.edu.au>
Currently, the context switch counters reported by getrusage() are
always zero. The appended patch adds fields to struct task_struct to
count context switches, and adds code to do the counting.
The patch adds 4 longs to struct task struct, and a single addition to
the fast path in schedule().
Add context switch counters to struct task_struct; add code to update them
in schedule(), initialise them in copy_mm(), and copy them to user space in
getrusage().
include/linux/sched.h | 1 +
kernel/exit.c | 2 ++
kernel/fork.c | 1 +
kernel/sched.c | 3 ++-
kernel/sys.c | 6 ++++++
5 files changed, 12 insertions(+), 1 deletion(-)
diff -puN include/linux/sched.h~rusage-context-switch-counters include/linux/sched.h
--- 25/include/linux/sched.h~rusage-context-switch-counters 2003-08-26 18:18:54.000000000 -0700
+++ 25-akpm/include/linux/sched.h 2003-08-26 18:19:47.000000000 -0700
@@ -393,6 +393,7 @@ struct task_struct {
struct timer_list real_timer;
struct list_head posix_timers; /* POSIX.1b Interval Timers */
unsigned long utime, stime, cutime, cstime;
+ unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw; /* context switch counts */
u64 start_time;
/* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */
unsigned long min_flt, maj_flt, nswap, cmin_flt, cmaj_flt, cnswap;
diff -puN kernel/exit.c~rusage-context-switch-counters kernel/exit.c
--- 25/kernel/exit.c~rusage-context-switch-counters 2003-08-26 18:18:54.000000000 -0700
+++ 25-akpm/kernel/exit.c 2003-08-26 18:18:54.000000000 -0700
@@ -80,6 +80,8 @@ void release_task(struct task_struct * p
p->parent->cmin_flt += p->min_flt + p->cmin_flt;
p->parent->cmaj_flt += p->maj_flt + p->cmaj_flt;
p->parent->cnswap += p->nswap + p->cnswap;
+ p->parent->cnvcsw += p->nvcsw + p->cnvcsw;
+ p->parent->cnivcsw += p->nivcsw + p->cnivcsw;
sched_exit(p);
write_unlock_irq(&tasklist_lock);
spin_unlock(&p->proc_lock);
diff -puN kernel/fork.c~rusage-context-switch-counters kernel/fork.c
--- 25/kernel/fork.c~rusage-context-switch-counters 2003-08-26 18:18:54.000000000 -0700
+++ 25-akpm/kernel/fork.c 2003-08-26 18:19:43.000000000 -0700
@@ -461,6 +461,7 @@ static int copy_mm(unsigned long clone_f
tsk->min_flt = tsk->maj_flt = 0;
tsk->cmin_flt = tsk->cmaj_flt = 0;
tsk->nswap = tsk->cnswap = 0;
+ tsk->nvcsw = tsk->nivcsw = tsk->cnvcsw = tsk->cnivcsw = 0;
tsk->mm = NULL;
tsk->active_mm = NULL;
diff -puN kernel/sched.c~rusage-context-switch-counters kernel/sched.c
--- 25/kernel/sched.c~rusage-context-switch-counters 2003-08-26 18:18:54.000000000 -0700
+++ 25-akpm/kernel/sched.c 2003-08-26 18:19:47.000000000 -0700
@@ -1324,8 +1324,9 @@ need_resched:
}
default:
deactivate_task(prev, rq);
+ prev->nvcsw++;
case TASK_RUNNING:
- ;
+ prev->nivcsw++;
}
pick_next_task:
if (unlikely(!rq->nr_running)) {
diff -puN kernel/sys.c~rusage-context-switch-counters kernel/sys.c
--- 25/kernel/sys.c~rusage-context-switch-counters 2003-08-26 18:18:54.000000000 -0700
+++ 25-akpm/kernel/sys.c 2003-08-26 18:18:54.000000000 -0700
@@ -1321,6 +1321,8 @@ int getrusage(struct task_struct *p, int
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;
r.ru_nswap = p->nswap;
@@ -1328,6 +1330,8 @@ int getrusage(struct task_struct *p, int
case RUSAGE_CHILDREN:
jiffies_to_timeval(p->cutime, &r.ru_utime);
jiffies_to_timeval(p->cstime, &r.ru_stime);
+ r.ru_nvcsw = p->cnvcsw;
+ r.ru_nivcsw = p->cnivcsw;
r.ru_minflt = p->cmin_flt;
r.ru_majflt = p->cmaj_flt;
r.ru_nswap = p->cnswap;
@@ -1335,6 +1339,8 @@ int getrusage(struct task_struct *p, int
default:
jiffies_to_timeval(p->utime + p->cutime, &r.ru_utime);
jiffies_to_timeval(p->stime + p->cstime, &r.ru_stime);
+ r.ru_nvcsw = p->nvcsw + p->cnvcsw;
+ r.ru_nivcsw = p->nivcsw + p->cnivcsw;
r.ru_minflt = p->min_flt + p->cmin_flt;
r.ru_majflt = p->maj_flt + p->cmaj_flt;
r.ru_nswap = p->nswap + p->cnswap;
_