linux-kernel - Re: [PATCH] lowmemorykiller: Avoid excessive/redundant calling of LMK

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Date:	Mon, 12 Jan 2015 21:44:27 +0530
From:	Chintan Pandya <cpandya@...eaurora.org>
To:	Chintan Pandya <cpandya@...eaurora.org>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Weijie Yang <weijie.yang@...sung.com>,
	David Rientjes <rientjes@...gle.com>,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, linux-mm@...ck.org
Subject: Re: [PATCH] lowmemorykiller: Avoid excessive/redundant calling of
 LMK

Please ignore this patch. My extreme bad that I merged commit messages 
applicable to some very old kernel into this patch. Updating shortly.

On 01/12/2015 09:38 PM, Chintan Pandya wrote:
> The global shrinker will invoke lowmem_shrink in a loop.
> The loop will be run (total_scan_pages/batch_size) times.
> The default batch_size will be 128 which will make
> shrinker invoking 100s of times. LMK does meaningful
> work only during first 2-3 times and then rest of the
> invocations are just CPU cycle waste. Fix that by giving
> excessively large batch size so that lowmem_shrink will
> be called just once and in the same try LMK does the
> needful.
>
> Signed-off-by: Chintan Pandya<cpandya@...eaurora.org>
> ---
>   drivers/staging/android/lowmemorykiller.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
> index b545d3d..5bf483f 100644
> --- a/drivers/staging/android/lowmemorykiller.c
> +++ b/drivers/staging/android/lowmemorykiller.c
> @@ -110,7 +110,7 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
>   	if (min_score_adj == OOM_SCORE_ADJ_MAX + 1) {
>   		lowmem_print(5, "lowmem_scan %lu, %x, return 0\n",
>   			     sc->nr_to_scan, sc->gfp_mask);
> -		return 0;
> +		return SHRINK_STOP;
>   	}
>
>   	selected_oom_score_adj = min_score_adj;
> @@ -163,6 +163,9 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
>   		set_tsk_thread_flag(selected, TIF_MEMDIE);
>   		send_sig(SIGKILL, selected, 0);
>   		rem += selected_tasksize;
> +	} else {
> +		rcu_read_unlock();
> +		return SHRINK_STOP;
>   	}
>
>   	lowmem_print(4, "lowmem_scan %lu, %x, return %lu\n",


-- 
Chintan Pandya

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