Re: [PATCH 2/3] f2fs: add sysfs entries to select the gc policy

[Gu Zheng]

On 08/04/2013 10:10 PM, Namjae Jeon wrote:

> From: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
> 
> Add sysfs entry gc_idle to control the gc policy. Where
> gc_idle = 1 corresponds to selecting a cost benefit approach,
> while gc_idle = 2 corresponds to selecting a greedy approach
> to garbage collection. The selection is mutually exclusive one
> approach will work at any point. If gc_idle = 0, then this
> option is disabled.
> 
> Cc: Gu Zheng <guz.fnst@xxxxxxxxxxxxxx>
> Signed-off-by: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
> Signed-off-by: Pankaj Kumar <pankaj.km@xxxxxxxxxxx>


Reviewed-by: Gu Zheng <guz.fnst@xxxxxxxxxxxxxx>

> ---
>  Documentation/ABI/testing/sysfs-fs-f2fs |    6 +++++-
>  Documentation/filesystems/f2fs.txt      |    6 ++++++
>  fs/f2fs/gc.c                            |   24 +++++++++++++++++++++---
>  fs/f2fs/gc.h                            |    3 +++
>  fs/f2fs/super.c                         |    2 ++
>  5 files changed, 37 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
> index 5f44095..31942ef 100644
> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> @@ -19,4 +19,8 @@ Description:
>  		 Controls the default sleep time for gc_thread. Time
>  		 is in milliseconds.
>  
> -
> +What:		/sys/fs/f2fs/<disk>/gc_idle
> +Date:		July 2013
> +Contact:	"Namjae Jeon" <namjae.jeon@xxxxxxxxxxx>
> +Description:
> +		 Controls the victim selection policy for garbage collection.
> diff --git a/Documentation/filesystems/f2fs.txt b/Documentation/filesystems/f2fs.txt
> index 5daf3bb..3cd27be 100644
> --- a/Documentation/filesystems/f2fs.txt
> +++ b/Documentation/filesystems/f2fs.txt
> @@ -158,6 +158,12 @@ Files in /sys/fs/f2fs/<devname>
>                                time for the garbage collection thread. Time is
>                                in milliseconds.
>  
> + gc_idle                      This parameter controls the selection of victim
> +                              policy for garbage collection. Setting gc_idle = 0
> +                              (default) will disable this option. Setting
> +                              gc_idle = 1 will select the Cost Benefit approach
> +                              & setting gc_idle = 2 will select the greedy aproach.
> +
>  ================================================================================
>  USAGE
>  ================================================================================
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 60d4f67..2c0c8ad 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -106,6 +106,8 @@ int start_gc_thread(struct f2fs_sb_info *sbi)
>  	gc_th->max_sleep_time = DEF_GC_THREAD_MAX_SLEEP_TIME;
>  	gc_th->no_gc_sleep_time = DEF_GC_THREAD_NOGC_SLEEP_TIME;
>  
> +	gc_th->gc_idle = 0;
> +
>  	sbi->gc_thread = gc_th;
>  	init_waitqueue_head(&sbi->gc_thread->gc_wait_queue_head);
>  	sbi->gc_thread->f2fs_gc_task = kthread_run(gc_thread_func, sbi,
> @@ -130,9 +132,25 @@ void stop_gc_thread(struct f2fs_sb_info *sbi)
>  	sbi->gc_thread = NULL;
>  }
>  
> -static int select_gc_type(int gc_type)
> +static int select_gc_type(struct f2fs_gc_kthread *gc_th, int gc_type)
>  {
> -	return (gc_type == BG_GC) ? GC_CB : GC_GREEDY;
> +	int gc_mode;
> +
> +	if (gc_th && gc_th->gc_idle) {
> +		/* Cost Benefit Policy */
> +		if (gc_th->gc_idle == 1) {
> +			gc_mode = GC_CB;
> +			goto out;
> +		} else if (gc_th->gc_idle == 2) {
> +			/* Greedy Policy */
> +			gc_mode = GC_GREEDY;
> +			goto out;
> +		}
> +	}
> +
> +	gc_mode = (gc_type == BG_GC) ? GC_CB : GC_GREEDY;
> +out:
> +	return gc_mode;
>  }
>  
>  static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
> @@ -145,7 +163,7 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
>  		p->dirty_segmap = dirty_i->dirty_segmap[type];
>  		p->ofs_unit = 1;
>  	} else {
> -		p->gc_mode = select_gc_type(gc_type);
> +		p->gc_mode = select_gc_type(sbi->gc_thread, gc_type);
>  		p->dirty_segmap = dirty_i->dirty_segmap[DIRTY];
>  		p->ofs_unit = sbi->segs_per_sec;
>  	}
> diff --git a/fs/f2fs/gc.h b/fs/f2fs/gc.h
> index f4bf44c..c22dee9 100644
> --- a/fs/f2fs/gc.h
> +++ b/fs/f2fs/gc.h
> @@ -30,6 +30,9 @@ struct f2fs_gc_kthread {
>  	unsigned int min_sleep_time;
>  	unsigned int max_sleep_time;
>  	unsigned int no_gc_sleep_time;
> +
> +	/* for changing gc mode */
> +	unsigned int gc_idle;
>  };
>  
>  struct inode_entry {
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 0a3e88f..f9c6c0b 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -148,12 +148,14 @@ static struct f2fs_attr f2fs_attr_##_name = {			\
>  F2FS_RW_ATTR(gc_min_sleep_time, min_sleep_time);
>  F2FS_RW_ATTR(gc_max_sleep_time, max_sleep_time);
>  F2FS_RW_ATTR(gc_no_gc_sleep_time, no_gc_sleep_time);
> +F2FS_RW_ATTR(gc_idle, gc_idle);
>  
>  #define ATTR_LIST(name) (&f2fs_attr_##name.attr)
>  static struct attribute *f2fs_attrs[] = {
>  	ATTR_LIST(gc_min_sleep_time),
>  	ATTR_LIST(gc_max_sleep_time),
>  	ATTR_LIST(gc_no_gc_sleep_time),
> +	ATTR_LIST(gc_idle),
>  	NULL,
>  };
>  


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