From: Heesub Shin <heesub.shin@samsung.com>
To: Minchan Kim <minchan@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Hugh Dickins <hughd@google.com>, Shaohua Li <shli@kernel.org>,
Jerome Marchand <jmarchan@redhat.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Dan Streetman <ddstreet@ieee.org>,
Nitin Gupta <ngupta@vflare.org>,
Luigi Semenzato <semenzato@google.com>
Subject: Re: [RFC 3/3] zram: add swap_get_free hint
Date: Thu, 04 Sep 2014 15:26:14 +0900 [thread overview]
Message-ID: <54080606.3050106@samsung.com> (raw)
In-Reply-To: <1409794786-10951-4-git-send-email-minchan@kernel.org>
Hello Minchan,
First of all, I agree with the overall purpose of your patch set.
On 09/04/2014 10:39 AM, Minchan Kim wrote:
> This patch implement SWAP_GET_FREE handler in zram so that VM can
> know how many zram has freeable space.
> VM can use it to stop anonymous reclaiming once zram is full.
>
> Signed-off-by: Minchan Kim <minchan@kernel.org>
> ---
> drivers/block/zram/zram_drv.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 88661d62e46a..8e22b20aa2db 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -951,6 +951,22 @@ static int zram_slot_free_notify(struct block_device *bdev,
> return 0;
> }
>
> +static int zram_get_free_pages(struct block_device *bdev, long *free)
> +{
> + struct zram *zram;
> + struct zram_meta *meta;
> +
> + zram = bdev->bd_disk->private_data;
> + meta = zram->meta;
> +
> + if (!zram->limit_pages)
> + return 1;
> +
> + *free = zram->limit_pages - zs_get_total_pages(meta->mem_pool);
Even if 'free' is zero here, there may be free spaces available to store
more compressed pages into the zs_pool. I mean calculation above is not
quite accurate and wastes memory, but have no better idea for now.
heesub
> +
> + return 0;
> +}
> +
> static int zram_swap_hint(struct block_device *bdev,
> unsigned int hint, void *arg)
> {
> @@ -958,6 +974,8 @@ static int zram_swap_hint(struct block_device *bdev,
>
> if (hint == SWAP_SLOT_FREE)
> ret = zram_slot_free_notify(bdev, (unsigned long)arg);
> + else if (hint == SWAP_GET_FREE)
> + ret = zram_get_free_pages(bdev, arg);
>
> return ret;
> }
>
next prev parent reply other threads:[~2014-09-04 6:25 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-04 1:39 [RFC 0/3] make vm aware of zram-swap Minchan Kim
2014-09-04 1:39 ` [RFC 1/3] zram: generalize swap_slot_free_notify Minchan Kim
2014-09-04 1:39 ` [RFC 2/3] mm: add swap_get_free hint for zram Minchan Kim
2014-09-13 19:01 ` Dan Streetman
2014-09-15 0:30 ` Minchan Kim
2014-09-15 14:53 ` Dan Streetman
2014-09-16 0:33 ` Minchan Kim
2014-09-16 15:09 ` Dan Streetman
2014-09-17 7:14 ` Minchan Kim
2014-09-04 1:39 ` [RFC 3/3] zram: add swap_get_free hint Minchan Kim
2014-09-04 6:26 ` Heesub Shin [this message]
2014-09-04 23:59 ` Minchan Kim
2014-09-13 19:39 ` Dan Streetman
2014-09-15 0:57 ` Minchan Kim
2014-09-15 16:00 ` Dan Streetman
2014-09-16 1:21 ` Minchan Kim
2014-09-16 15:58 ` Dan Streetman
2014-09-17 7:44 ` Minchan Kim
2014-09-17 16:28 ` Dan Streetman
2014-09-19 6:14 ` Minchan Kim
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