linux-kernel - Re: [patch 1/7] lowmemorykiller: Only iterate over process list when needed.

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Date:	Tue, 5 May 2009 12:23:59 +0200
From:	Nick Piggin <npiggin@...e.de>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	San Mehat <san@...roid.com>,
	Arve Hjønnevåg <arve@...roid.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [patch 1/7] lowmemorykiller: Only iterate over process list when needed.

On Mon, May 04, 2009 at 05:26:50PM -0700, David Rientjes wrote:
> From: Arve Hjønnevåg <arve@...roid.com>
> 
> Use NR_ACTIVE plus NR_INACTIVE as a size estimate for our fake cache
> instead the sum of rss. Neither method is accurate.
> 
> Also skip the process scan, if the amount of memory available is above
> the largest threshold set.
> 
> Signed-off-by: Arve Hjønnevåg <arve@...roid.com>

Didn't really look at the android stuff because I didn't even know
it was there before. But I asume it is going to be "submitted" to
the kernel proper at some stage (by some means other than a git rename) :)

> ---
>  drivers/staging/android/lowmemorykiller.c |   35 +++++++++++++++++-----------
>  1 files changed, 21 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
> --- a/drivers/staging/android/lowmemorykiller.c
> +++ b/drivers/staging/android/lowmemorykiller.c
> @@ -71,23 +71,30 @@ static int lowmem_shrink(int nr_to_scan, gfp_t gfp_mask)
>  	}
>  	if(nr_to_scan > 0)
>  		lowmem_print(3, "lowmem_shrink %d, %x, ofree %d, ma %d\n", nr_to_scan, gfp_mask, other_free, min_adj);
> +	rem = global_page_state(NR_ACTIVE) + global_page_state(NR_INACTIVE);
> +	if (nr_to_scan <= 0 || min_adj == OOM_ADJUST_MAX + 1) {
> +		lowmem_print(5, "lowmem_shrink %d, %x, return %d\n", nr_to_scan, gfp_mask, rem);
> +		return rem;
> +	}
> +
>  	read_lock(&tasklist_lock);
>  	for_each_process(p) {
> -		if(p->oomkilladj >= 0 && p->mm) {
> -			tasksize = get_mm_rss(p->mm);
> -			if(nr_to_scan > 0 && tasksize > 0 && p->oomkilladj >= min_adj) {
> -				if(selected == NULL ||
> -				   p->oomkilladj > selected->oomkilladj ||
> -				   (p->oomkilladj == selected->oomkilladj &&
> -				    tasksize > selected_tasksize)) {
> -					selected = p;
> -					selected_tasksize = tasksize;
> -					lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n",
> -					             p->pid, p->comm, p->oomkilladj, tasksize);
> -				}
> -			}
> -			rem += tasksize;
> +		if (p->oomkilladj < min_adj || !p->mm)
> +			continue;
> +		tasksize = get_mm_rss(p->mm);
> +		if (tasksize <= 0)
> +			continue;
> +		if (selected) {
> +			if (p->oomkilladj < selected->oomkilladj)
> +				continue;
> +			if (p->oomkilladj == selected->oomkilladj &&
> +			    tasksize <= selected_tasksize)
> +				continue;
>  		}
> +		selected = p;
> +		selected_tasksize = tasksize;
> +		lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n",
> +		             p->pid, p->comm, p->oomkilladj, tasksize);
>  	}
>  	if(selected != NULL) {
>  		lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
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