linux-kernel - Re: [PATCH, RESEND3] getrusage: fill ru

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Date:	Wed, 24 Dec 2008 16:37:55 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Jiri Pirko <jpirko@...hat.com>
Cc:	kosaki.motohiro@...fujitsu.com, linux-kernel@...r.kernel.org,
	<oleg@...hat.com>
Subject: Re: [PATCH, RESEND3] getrusage: fill ru_maxrss value

Hi

> diff --git a/fs/exec.c b/fs/exec.c
> index ec5df9a..8d3d0f9 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -870,6 +870,7 @@ static int de_thread(struct task_struct *tsk)
>  	sig->notify_count = 0;
>  
>  no_thread_group:
> +	sig->maxrss = 0;
>  	exit_itimers(sig);
>  	flush_itimer_signals();
>  	if (leader)

I don't know getrusage correct behavior so detail.
Why don't update parent process's sig->cmaxrss ?


> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index f4c70dc..41b04ee 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -563,6 +563,7 @@ struct signal_struct {
>  	unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
>  	unsigned long inblock, oublock, cinblock, coublock;
>  	struct task_io_accounting ioac;
> +	unsigned long maxrss, cmaxrss;

	unsigned long inblock, oublock, cinblock, coublock;
	unsigned long maxrss, cmaxrss;
	struct task_io_accounting ioac;

is better.
I like related member sit on nearly place.



> diff --git a/kernel/exit.c b/kernel/exit.c
> index 81b6372..61d622d 100644
> --- a/kernel/exit.c
> +++ b/kernel/exit.c
> @@ -1053,6 +1053,8 @@ NORET_TYPE void do_exit(long code)
>  	if (group_dead) {
>  		hrtimer_cancel(&tsk->signal->real_timer);
>  		exit_itimers(tsk->signal);
> +		if (tsk->mm)
> +			tsk->signal->maxrss = get_mm_hiwater_rss(tsk->mm);
>  	}
>  	acct_collect(code, group_dead);
>  	if (group_dead)

At first look, I think "hm, group_dead mean this thread is last thread.
hehe, this assignment is obiously meaningless".
but it is wrong. you inserted maxrss usage in wait_task_zombie().

I think this is a bit confusable code.
I hope you add kindly comment here.



> @@ -1351,6 +1353,8 @@ static int wait_task_zombie(struct task_struct *p, int options,
>  			sig->oublock + sig->coublock;
>  		task_io_accounting_add(&psig->ioac, &p->ioac);
>  		task_io_accounting_add(&psig->ioac, &sig->ioac);
> +		if (psig->cmaxrss < sig->maxrss)
> +			psig->cmaxrss = sig->maxrss;
>  		spin_unlock_irq(&p->parent->sighand->siglock);
>  	}

ditto. I like following order.

			sig->oublock + sig->coublock;
		if (psig->cmaxrss < sig->maxrss)
			psig->cmaxrss = sig->maxrss;
		task_io_accounting_add(&psig->ioac, &p->ioac);
		task_io_accounting_add(&psig->ioac, &sig->ioac);



> diff --git a/kernel/fork.c b/kernel/fork.c
> index 495da2e..36ac3e5 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -850,6 +850,7 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
>  	sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
>  	sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0;
>  	task_io_accounting_init(&sig->ioac);
> +	sig->maxrss = sig->cmaxrss = 0;
>  	taskstats_tgid_init(sig);
>  
>  	task_lock(current->group_leader);
> diff --git a/kernel/sys.c b/kernel/sys.c
> index 31deba8..f369099 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -1569,6 +1569,7 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
>  			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;
> @@ -1583,6 +1584,8 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
>  			r->ru_majflt += p->signal->maj_flt;
>  			r->ru_inblock += p->signal->inblock;
>  			r->ru_oublock += p->signal->oublock;
> +			if (r->ru_maxrss < p->signal->maxrss)
> +				r->ru_maxrss = p->signal->maxrss;
>  			t = p;
>  			do {
>  				accumulate_thread_rusage(t, r);
> @@ -1598,6 +1601,18 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
>  out:
>  	cputime_to_timeval(utime, &r->ru_utime);
>  	cputime_to_timeval(stime, &r->ru_stime);
> +
> +	if (who != RUSAGE_CHILDREN) {
> +		task_lock(p);
> +		if (p->mm) {
> +			unsigned long maxrss = get_mm_hiwater_rss(p->mm);
> +
> +			if (r->ru_maxrss < maxrss)
> +				r->ru_maxrss = maxrss;
> +		}
> +		task_unlock(p);

get_task_mm() and mmput() instead task_lock() is better?

and, why don't this code move to "case RUSAGE_SELF" processing point?


> +	}
> +	r->ru_maxrss <<= PAGE_SHIFT - 10;
>  }

using local variable is better because local variable can stay on
register by compiler easily, but indirect access doesn't.

r->ru_maxrss = maxrss << PAGE_SHIFT - 10;
(similar utime and r->ru_utime)

and we need good comment. e.g. /* Convert to KB */
or good macros (likely linux/fs/proc/meminfo.c::K() macro)


>  
>  int getrusage(struct task_struct *p, int who, struct rusage __user *ru)
> -- 
> 1.6.0.4
> 

In addision, you also need change man pages and notice to linux-api mailing list.




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