Properly support the ru_maxrss field of the rusage structure returned by
getrusage(). This patch includes documentation both of the getrusage()
implementation in general and of the ru_maxrss implementation
specifically. This implementation matches that of FreeBSD, which is the
only other OS of which I'm aware that implements this field.
Like a number of other folks, we recently had a need for a non-/proc way
of getting the RSS of a process and happened on getrusage(). Unlike the
rest, though, we fixed the system call to do what we want. I wrote a
wrong implementation and submitted it while I was sick; this time I took
my time and I think I got it right.
A test program that has been run against a number of systems (of which
only FreeBSD and Linux 2.6 with this patch applied passed) is also
available at
http://www.exit.com/Archives/Linux/
Signed-off-by: Frank Mayhar <[email protected]>
---
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 3de7901..85735af 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -518,6 +518,7 @@ struct signal_struct {
unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
unsigned long inblock, oublock, cinblock, coublock;
+ unsigned long cmaxrss;
/*
* Cumulative ns of scheduled CPU time for dead threads in the
@@ -1027,6 +1028,8 @@ #endif
struct timespec real_start_time; /* boot based time */
/* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */
unsigned long min_flt, maj_flt;
+/* maxrss gets the hiwater_rss in do_exit() */
+ unsigned long maxrss;
cputime_t it_prof_expires, it_virt_expires;
unsigned long long it_sched_expires;
diff --git a/kernel/exit.c b/kernel/exit.c
index 06b24b3..390d834 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -127,6 +127,8 @@ static void __exit_signal(struct task_st
sig->inblock += task_io_get_inblock(tsk);
sig->oublock += task_io_get_oublock(tsk);
sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
+ if (tsk->maxrss > sig->cmaxrss)
+ sig->cmaxrss = tsk->maxrss;
sig = NULL; /* Marker for below. */
}
@@ -957,6 +959,14 @@ fastcall NORET_TYPE void do_exit(long co
if (tsk->mm) {
update_hiwater_rss(tsk->mm);
update_hiwater_vm(tsk->mm);
+ BUG_ON(tsk->maxrss != 0);
+ /*
+ * Store the hiwater_rss in a task field, since when we need
+ * it in __exit_signal() the mm structure is gone; we can't
+ * stuff it in the signal structure since then we would be
+ * racing with wait_task_zombie().
+ */
+ tsk->maxrss = tsk->mm->hiwater_rss;
}
group_dead = atomic_dec_and_test(&tsk->signal->live);
if (group_dead) {
@@ -1265,6 +1275,17 @@ static int wait_task_zombie(struct task_
psig->coublock +=
task_io_get_oublock(p) +
sig->oublock + sig->coublock;
+ /*
+ * Save the maximum RSS of this task and all its terminated,
+ * waited-for children. Don't accumulate the RSS since, one,
+ * other operating systems (FreeBSD, AIX) do it this way and,
+ * two, the cumulative RSS of a long-lived process with lots
+ * of sequential child process would be meaningless.
+ */
+ if (sig->cmaxrss > psig->cmaxrss)
+ psig->cmaxrss = sig->cmaxrss;
+ if (p->maxrss > psig->cmaxrss)
+ psig->cmaxrss = p->maxrss;
spin_unlock_irq(&p->parent->sighand->siglock);
}
diff --git a/kernel/fork.c b/kernel/fork.c
index 7332e23..fae76dd 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -536,6 +536,7 @@ static int copy_mm(unsigned long clone_f
tsk->min_flt = tsk->maj_flt = 0;
tsk->nvcsw = tsk->nivcsw = 0;
+ tsk->maxrss = 0;
tsk->mm = NULL;
tsk->active_mm = NULL;
@@ -881,6 +882,7 @@ static inline int copy_signal(unsigned l
sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0;
sig->sum_sched_runtime = 0;
+ sig->cmaxrss = 0;
INIT_LIST_HEAD(&sig->cpu_timers[0]);
INIT_LIST_HEAD(&sig->cpu_timers[1]);
INIT_LIST_HEAD(&sig->cpu_timers[2]);
diff --git a/kernel/sys.c b/kernel/sys.c
index 1b33b05..e450bab 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2099,6 +2099,7 @@ static void k_getrusage(struct task_stru
r->ru_majflt = p->signal->cmaj_flt;
r->ru_inblock = p->signal->cinblock;
r->ru_oublock = p->signal->coublock;
+ r->ru_maxrss = p->signal->cmaxrss;
if (who == RUSAGE_CHILDREN)
break;
@@ -2124,11 +2125,15 @@ static void k_getrusage(struct task_stru
r->ru_oublock += task_io_get_oublock(t);
t = next_thread(t);
} while (t != p);
+ update_hiwater_rss(p->mm);
+ if (r->ru_maxrss < p->mm->hiwater_rss)
+ r->ru_maxrss = p->mm->hiwater_rss;
break;
default:
BUG();
}
+ r->ru_maxrss <<= PAGE_SHIFT - 10; /* Convert from pages to kilobytes. */
unlock_task_sighand(p, &flags);
rcu_read_unlock();
--
Frank Mayhar <[email protected]>
Google, Inc.
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