Date:	Wed, 31 Dec 2008 21:42:36 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Jiri Pirko <jpirko@...hat.com>
Cc:	kosaki.motohiro@...fujitsu.com, Oleg Nesterov <oleg@...hat.com>,
	linux-kernel@...r.kernel.org, Hugh Dickins <hugh@...itas.com>,
	linux-mm <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH for -mm] getrusage: fill ru_maxrss value

Hi!

> > Changes Jiris's last version
> >   - At wait_task_zombie(), parent process doesn't only collect child maxrss,
> >     but also cmaxrss.
> Yes, this is what we were missing so far.
> 
> >   - ru_maxrss inherit at exec()
> >   - style fixes.
> 
> New patch seems almost fine to me. Only I do not like usage of max()
> macro in do_exit() and in de_thread(). It's unnecessary and little
> wasting (yes only a little :)). This two spots would be maybe better
> solved with if(<).

Done!



Changelog
v1 -> v2
  - Removed unnecessary max() macro
  - To avoid ru_maxrss recalculation in k_getrusage()
  - style fixes

Jiri's resend3 -> v1
 - At wait_task_zombie(), parent process doesn't only collect child maxrss,
   but also cmaxrss.
 - ru_maxrss inherit at exec()
 - style fixes


Applied after: introduce-get_mm_hiwater_xxx-fix-taskstats-hiwater_xxx-accounting.patch
==
From: Signed-off-by: Jiri Pirko <jpirko@...hat.com>
Subject: [PATCH for -mm] getrusage: fill ru_maxrss value

This patch makes ->ru_maxrss value in struct rusage filled accordingly to
rss hiwater mark. This struct is filled as a parameter to
getrusage syscall. ->ru_maxrss value is set to KBs which is the way it
is done in BSD systems. /usr/bin/time (gnu time) application converts
->ru_maxrss to KBs which seems to be incorrect behavior. Maintainer of
this util was notified by me with the patch which corrects it and cc'ed.

To make this happen we extend struct signal_struct by two fields. The
first one is ->maxrss which we use to store rss hiwater of the task. The
second one is ->cmaxrss which we use to store highest rss hiwater of all
task childs. These values are used in k_getrusage() to actually fill
->ru_maxrss. k_getrusage() uses current rss hiwater value directly
if mm struct exists.

Note:
exec() clear mm->hiwater_rss, but doesn't clear sig->maxrss.
it is intetionally behavior. *BSD getrusage have exec() inheriting.


Test progmam and test case
===========================

getrusage.c
----
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <signal.h>

static void consume(int mega)
{
	size_t sz = mega * 1024 * 1024;
	void *ptr;

	ptr = malloc(sz);
	memset(ptr, 0, sz);
	usleep(1);  /* BSD rusage statics need to sleep 1 tick */
}

static void show_rusage(char *prefix)
{
	int err, err2;
	struct rusage rusage_self;
	struct rusage rusage_children;

	printf("%s: ", prefix);
	err = getrusage(RUSAGE_SELF, &rusage_self);
	if (!err)
		printf("self %ld ", rusage_self.ru_maxrss);
	err2 = getrusage(RUSAGE_CHILDREN, &rusage_children);
	if (!err2)
		printf("children %ld ", rusage_children.ru_maxrss);

	printf("\n");
}

int main(int argc, char** argv)
{
	int status;
	int c;
	int need_sleep_before_wait = 0;
	int consume_large_memory_at_first = 0;
	int create_child_at_first = 0;
	int sigign = 0;
	int create_child_before_exec = 0;
	int after_fork_test = 0;

	while ((c = getopt(argc, argv, "ceflsz")) != -1) {
		switch (c) {
		case 'c':
			create_child_at_first = 1;
			break;
		case 'e':
			create_child_before_exec = 1;
			break;
		case 'f':
			after_fork_test = 1;
			break;
		case 'l':
			consume_large_memory_at_first = 1;
			break;
		case 's':
			sigign = 1;
			break;
		case 'z':
			need_sleep_before_wait = 1;
			break;
		default:
			break;
		}
	}

	if (consume_large_memory_at_first)
		consume(100);   

	if (create_child_at_first)
		system("./child -q"); 
	
	if (sigign)
		signal(SIGCHLD, SIG_IGN);

	if (fork()) {
		usleep(1);
		if (need_sleep_before_wait)
			sleep(3); /* children become zombie */
		show_rusage("pre_wait");
		wait(&status);
		show_rusage("post_wait");
	} else {
		usleep(1);
		show_rusage("fork");
		
		if (after_fork_test) {
			consume(30);
			show_rusage("fork2");
		}
		if (create_child_before_exec) {
			system("./child -lq"); 
			usleep(1);
			show_rusage("fork3");
		}

		execl("./child", "child", 0);
		exit(0);
	}
	     
	return 0;
}

child.c
----
#include <sys/types.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>

static void consume(int mega)
{
	size_t sz = mega * 1024 * 1024;
	void *ptr;

	ptr = malloc(sz);
	memset(ptr, 0, sz);
	usleep(1);  /* BSD rusage statics need to sleep 1 tick */
}

static void show_rusage(char *prefix)
{
	int err, err2;
	struct rusage rusage_self;
	struct rusage rusage_children;

	printf("%s: ", prefix);
	err = getrusage(RUSAGE_SELF, &rusage_self);
	if (!err)
		printf("self %ld ", rusage_self.ru_maxrss);
	err2 = getrusage(RUSAGE_CHILDREN, &rusage_children);
	if (!err2)
		printf("children %ld ", rusage_children.ru_maxrss);

	printf("\n");

}


int main(int argc, char** argv)
{
	int status;
	int c;
	int silent = 0;
	int light_weight = 0;

	while ((c = getopt(argc, argv, "lq")) != -1) {
		switch (c) {
		case 'l':
			light_weight = 1;
			break;
		case 'q':
			silent = 1;
			break;
		default:
			break;
		}
	}

	if (!silent)
		show_rusage("exec");

	if (fork()) {
		if (light_weight)
			consume(400);
		else
			consume(700);
		wait(&status);
	} else {
		if (light_weight)
			consume(600);
		else
			consume(900);

		exit(0);
	}

	return 0;
}

testcase
==================
1. inherit fork?
   
   test way:
   	% ./getrusage -lc 

   bsd result:
   	fork line is "fork: self 0 children 0".

   	-> rusage sholdn't be inherit by fork.
	   (both RUSAGE_SELF and RUSAGE_CHILDREN)

2. inherit exec?

   test way:
   	% ./getrusage -lce

   bsd result:
   	fork3: self 103204 children 60000 
	exec: self 103204 children 60000

   	fork3 and exec line are the same.

   	-> rusage shold be inherit by exec.
	   (both RUSAGE_SELF and RUSAGE_CHILDREN)

3. getrusage(RUSAGE_CHILDREN) collect grandchild statics?

   test way:
   	% ./getrusage

   bsd result:
   	post_wait line is about "post_wait: self 0 children 90000".

	-> RUSAGE_CHILDREN can collect grandchild.

4. zombie, but not waited children collect or not?

   test way:
   	% ./getrusage -z

   bsd result:
   	pre_wait line is "pre_wait: self 0 children 0".

	-> zombie child process (not waited-for child process)
	   isn't accounted.

5. SIG_IGN collect or not

   test way:
   	% ./getrusage -s

   bsd result:
   	post_wait line is "post_wait: self 0 children 0".

	-> if SIGCHLD is ignored, children isn't accounted.

6. fork and malloc
   test way:
   	% ./getrusage -lcf

   bsd result:
   	fork line is "fork: self 0 children 0".
   	fork2 line is about "fork: self 130000 children 0".

   	-> rusage sholdn't be inherit by fork.
	   (both RUSAGE_SELF and RUSAGE_CHILDREN)
	   but additional memory cunsumption cause right
	   maxrss calculation.


Signed-off-by: Jiri Pirko <jpirko@...hat.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
---
 fs/exec.c             |    7 +++++++
 include/linux/sched.h |    1 +
 kernel/exit.c         |   10 ++++++++++
 kernel/fork.c         |    1 +
 kernel/sys.c          |   16 ++++++++++++++++
 5 files changed, 35 insertions(+)

Index: b/include/linux/sched.h
===================================================================
--- a/include/linux/sched.h	2008-12-29 23:27:59.000000000 +0900
+++ b/include/linux/sched.h	2008-12-30 03:25:23.000000000 +0900
@@ -562,6 +562,7 @@ 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 maxrss, cmaxrss;
 	struct task_io_accounting ioac;
 
 	/*
Index: b/kernel/exit.c
===================================================================
--- a/kernel/exit.c	2008-12-29 23:27:59.000000000 +0900
+++ b/kernel/exit.c	2008-12-31 21:08:08.000000000 +0900
@@ -1053,6 +1053,12 @@ NORET_TYPE void do_exit(long code)
 	if (group_dead) {
 		hrtimer_cancel(&tsk->signal->real_timer);
 		exit_itimers(tsk->signal);
+		if (tsk->mm) {
+			unsigned long hiwater_rss = get_mm_hiwater_rss(tsk->mm);
+
+			if (tsk->signal->maxrss < hiwater_rss)
+				tsk->signal->maxrss = hiwater_rss;
+		}
 	}
 	acct_collect(code, group_dead);
 	if (group_dead)
@@ -1298,6 +1304,7 @@ static int wait_task_zombie(struct task_
 		struct signal_struct *psig;
 		struct signal_struct *sig;
 		struct task_cputime cputime;
+		unsigned long maxrss;
 
 		/*
 		 * The resource counters for the group leader are in its
@@ -1349,6 +1356,9 @@ static int wait_task_zombie(struct task_
 		psig->coublock +=
 			task_io_get_oublock(p) +
 			sig->oublock + sig->coublock;
+		maxrss = max(sig->maxrss, sig->cmaxrss);
+		if (psig->cmaxrss < maxrss)
+			psig->cmaxrss = maxrss;
 		task_io_accounting_add(&psig->ioac, &p->ioac);
 		task_io_accounting_add(&psig->ioac, &sig->ioac);
 		spin_unlock_irq(&p->parent->sighand->siglock);
Index: b/kernel/fork.c
===================================================================
--- a/kernel/fork.c	2008-12-25 08:26:37.000000000 +0900
+++ b/kernel/fork.c	2008-12-30 03:48:09.000000000 +0900
@@ -849,6 +849,7 @@ static int copy_signal(unsigned long clo
 	sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
 	sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
 	sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0;
+	sig->maxrss = sig->cmaxrss = 0;
 	task_io_accounting_init(&sig->ioac);
 	taskstats_tgid_init(sig);
 
Index: b/kernel/sys.c
===================================================================
--- a/kernel/sys.c	2008-12-25 08:26:37.000000000 +0900
+++ b/kernel/sys.c	2008-12-31 21:06:03.000000000 +0900
@@ -1546,6 +1546,7 @@ static void k_getrusage(struct task_stru
 	unsigned long flags;
 	cputime_t utime, stime;
 	struct task_cputime cputime;
+	unsigned long maxrss = 0;
 
 	memset((char *) r, 0, sizeof *r);
 	utime = stime = cputime_zero;
@@ -1569,6 +1570,7 @@ 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;
+			maxrss = p->signal->cmaxrss;
 
 			if (who == RUSAGE_CHILDREN)
 				break;
@@ -1583,6 +1585,8 @@ static void k_getrusage(struct task_stru
 			r->ru_majflt += p->signal->maj_flt;
 			r->ru_inblock += p->signal->inblock;
 			r->ru_oublock += p->signal->oublock;
+			if (maxrss < p->signal->maxrss)
+				maxrss = p->signal->maxrss;
 			t = p;
 			do {
 				accumulate_thread_rusage(t, r);
@@ -1598,6 +1602,18 @@ static void k_getrusage(struct task_stru
 out:
 	cputime_to_timeval(utime, &r->ru_utime);
 	cputime_to_timeval(stime, &r->ru_stime);
+
+	if (who != RUSAGE_CHILDREN) {
+		struct mm_struct *mm = get_task_mm(p);
+		if (mm) {
+			unsigned long hiwater_rss = get_mm_hiwater_rss(mm);
+
+			if (maxrss < hiwater_rss)
+				maxrss = hiwater_rss;
+			mmput(mm);
+		}
+	}
+	r->ru_maxrss = maxrss * (PAGE_SIZE / 1024); /* convert pages to KBs */
 }
 
 int getrusage(struct task_struct *p, int who, struct rusage __user *ru)
Index: b/fs/exec.c
===================================================================
--- a/fs/exec.c	2008-12-25 08:26:37.000000000 +0900
+++ b/fs/exec.c	2008-12-31 21:11:28.000000000 +0900
@@ -870,6 +870,13 @@ static int de_thread(struct task_struct 
 	sig->notify_count = 0;
 
 no_thread_group:
+	if (current->mm) {
+		unsigned long hiwater_rss = get_mm_hiwater_rss(current->mm);
+
+		if (sig->maxrss < hiwater_rss)
+			sig->maxrss = hiwater_rss;
+	}
+
 	exit_itimers(sig);
 	flush_itimer_signals();
 	if (leader)


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