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

Gu Zheng
2013-08-05T02:04:12Z

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

> From: Namjae Jeon <namjae.jeon@samsung.com>
>
> 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@cn.fujitsu.com>
> Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
> Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>

Reviewed-by: Gu Zheng <guz.fnst@cn.fujitsu.com>

> ---
> 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@samsung.com>
> +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,
> };
>