linux-kernel - Re: [PATCHv2 06/10] zram: remove max_num

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Date:	Thu, 23 Apr 2015 11:36:36 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Nitin Gupta <ngupta@...are.org>, linux-kernel@...r.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Subject: Re: [PATCHv2 06/10] zram: remove max_num_devices limitation

On Thu, Apr 16, 2015 at 08:55:52PM +0900, Sergey Senozhatsky wrote:
> Limiting the number of zram devices to 32 (default max_num_devices value)
> is confusing, let's drop it.  A user with 2TB or 4TB of RAM, for example,
> can request as many devices as he can handle.
> 
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Acked-by: Minchan Kim <minchan@...nel.org>

I don't know you intentionally add new empty lines to make it clear
below but it's not related to this patch but I'm okay although you
did it to make to look better. Othewise, please fix when you respin.

> ---
>  Documentation/blockdev/zram.txt | 8 +++++++-
>  drivers/block/zram/zram_drv.c   | 8 +-------
>  drivers/block/zram/zram_drv.h   | 6 ------
>  3 files changed, 8 insertions(+), 14 deletions(-)
> 
> diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt
> index bef4998..2ccc741 100644
> --- a/Documentation/blockdev/zram.txt
> +++ b/Documentation/blockdev/zram.txt
> @@ -19,7 +19,9 @@ Following shows a typical sequence of steps for using zram.
>  1) Load Module:
>  	modprobe zram num_devices=4
>  	This creates 4 devices: /dev/zram{0,1,2,3}
> -	(num_devices parameter is optional. Default: 1)
> +
> +num_devices parameter is optional and tells zram how many devices should be
> +pre-created. Default: 1.
>  
>  2) Set max number of compression streams
>  	Compression backend may use up to max_comp_streams compression streams,
> @@ -128,6 +130,7 @@ mem_limit         RW    the maximum amount of memory ZRAM can use to store
>  num_migrated      RO    the number of objects migrated migrated by compaction
>  compact           WO    trigger memory compaction
>  
> +

?

>  WARNING
>  =======
>  per-stat sysfs attributes are considered to be deprecated.
> @@ -149,6 +152,7 @@ File /sys/block/zram<id>/stat
>  Represents block layer statistics. Read Documentation/block/stat.txt for
>  details.
>  
> +

?

>  File /sys/block/zram<id>/io_stat
>  
>  The stat file represents device's I/O statistics not accounted by block
> @@ -160,6 +164,7 @@ whitespace:
>  	invalid_io
>  	notify_free
>  
> +

?

>  File /sys/block/zram<id>/mm_stat
>  
>  The stat file represents device's mm statistics. It consists of a single
> @@ -172,6 +177,7 @@ line of text and contains the following stats separated by whitespace:
>  	zero_pages
>  	num_migrated
>  
> +

?

>  8) Deactivate:
>  	swapoff /dev/zram0
>  	umount /dev/zram1
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index e526fe1..c2d9b76 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -1288,12 +1288,6 @@ static int __init zram_init(void)
>  {
>  	int ret, dev_id;
>  
> -	if (num_devices > max_num_devices) {
> -		pr_warn("Invalid value for num_devices: %u\n",
> -				num_devices);
> -		return -EINVAL;
> -	}
> -
>  	zram_major = register_blkdev(0, "zram");
>  	if (zram_major <= 0) {
>  		pr_warn("Unable to get major number\n");
> @@ -1323,7 +1317,7 @@ module_init(zram_init);
>  module_exit(zram_exit);
>  
>  module_param(num_devices, uint, 0);
> -MODULE_PARM_DESC(num_devices, "Number of zram devices");
> +MODULE_PARM_DESC(num_devices, "Number of pre-created zram devices");
>  
>  MODULE_LICENSE("Dual BSD/GPL");
>  MODULE_AUTHOR("Nitin Gupta <ngupta@...are.org>");
> diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
> index 570c598..042994e 100644
> --- a/drivers/block/zram/zram_drv.h
> +++ b/drivers/block/zram/zram_drv.h
> @@ -20,12 +20,6 @@
>  
>  #include "zcomp.h"
>  
> -/*
> - * Some arbitrary value. This is just to catch
> - * invalid value for num_devices module parameter.
> - */
> -static const unsigned max_num_devices = 32;
> -
>  /*-- Configurable parameters */
>  
>  /*
> -- 
> 2.4.0.rc2
> 

-- 
Kind regards,
Minchan Kim
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