Hi Changman,
On Tue, Dec 23, 2014 at 08:37:38AM +0900, Changman Lee wrote:
> f2fs has 2 gc_type; foreground gc and background gc.
> In the case of foreground gc, f2fs will select victim as greedy.
> Otherwise, as cost-benefit. And also it runs as greedy in SSR mode.
> Until now, f2fs_gc conducted with BG_GC as default. So we couldn't
> expect how it runs; BG_GC or FG_GC and GREEDY or COST_BENEFIT.
What does this mean?
In f2fs_gc, the gc_type will be changed accoring to the number of free
sections.
> Therefore sometimes it runs as BG_GC/COST_BENEFIT although gc_thread
> don't put f2fs_gc to work.
You mean f2fs_balance_fs?
In this case, again, the gc_type will be assigned FG_GC.
Why do you want to set FG_GC/GREEDY for the SSR victims?
Thanks,
>
> Signed-off-by: Changman Lee <cm224.lee@xxxxxxxxxxx>
> ---
> fs/f2fs/f2fs.h | 2 +-
> fs/f2fs/gc.c | 5 ++---
> fs/f2fs/segment.c | 6 +++---
> 3 files changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index ae6dfb6..c956535 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1476,7 +1476,7 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *, u64, u64);
> int start_gc_thread(struct f2fs_sb_info *);
> void stop_gc_thread(struct f2fs_sb_info *);
> block_t start_bidx_of_node(unsigned int, struct f2fs_inode_info *);
> -int f2fs_gc(struct f2fs_sb_info *);
> +int f2fs_gc(struct f2fs_sb_info *, int);
> void build_gc_manager(struct f2fs_sb_info *);
> int __init create_gc_caches(void);
> void destroy_gc_caches(void);
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index eec0933..e1fa53a 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -80,7 +80,7 @@ static int gc_thread_func(void *data)
> stat_inc_bggc_count(sbi);
>
> /* if return value is not zero, no victim was selected */
> - if (f2fs_gc(sbi))
> + if (f2fs_gc(sbi, BG_GC))
> wait_ms = gc_th->no_gc_sleep_time;
>
> /* balancing f2fs's metadata periodically */
> @@ -691,10 +691,9 @@ static void do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,
> f2fs_put_page(sum_page, 1);
> }
>
> -int f2fs_gc(struct f2fs_sb_info *sbi)
> +int f2fs_gc(struct f2fs_sb_info *sbi, int gc_type)
> {
> unsigned int segno, i;
> - int gc_type = BG_GC;
> int nfree = 0;
> int ret = -1;
> struct cp_control cpc;
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index fd9bc96..3b32404 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -281,7 +281,7 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi)
> */
> if (has_not_enough_free_secs(sbi, 0)) {
> mutex_lock(&sbi->gc_mutex);
> - f2fs_gc(sbi);
> + f2fs_gc(sbi, FG_GC);
> }
> }
>
> @@ -994,12 +994,12 @@ static int get_ssr_segment(struct f2fs_sb_info *sbi, int type)
>
> if (IS_NODESEG(type) || !has_not_enough_free_secs(sbi, 0))
> return v_ops->get_victim(sbi,
> - &(curseg)->next_segno, BG_GC, type, SSR);
> + &(curseg)->next_segno, FG_GC, type, SSR);
>
> /* For data segments, let's do SSR more intensively */
> for (; type >= CURSEG_HOT_DATA; type--)
> if (v_ops->get_victim(sbi, &(curseg)->next_segno,
> - BG_GC, type, SSR))
> + FG_GC, type, SSR))
> return 1;
> return 0;
> }
> --
> 1.9.1
>
>
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