leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity

f2fs: fix calculation of max. gc cost in the SSR case

Browse Source 
In the SSR case, the max gc cost should be the number of pages in a segment.
Otherwise, f2fs is able to fail getting dirty segments frequently for SSR.

In get_victim_by_default() previously,

while(1) {
   ...
   cost = get_gc_cost(); <- cost is between 0 ~ 512.
   ...
   if (cost == get_max_cost(sbi, &p)) <- max cost is UINT_MAX due to GC_CB type
	continue;

   if (nsearched++ >= MAX_VICTIM_SEARCH)
	break;
}

So, if there are a number of fully valid segments in series, f2fs cannot skip
those segments by comparing the cost and max cost of each segment.

Note that, the cost is the number of valid blocks at the time of the last
checkpoint.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This commit is contained in:
Jaegeuk Kim 2013-02-05 13:19:28 +09:00
parent 437275272f
commit b7250d2d84
1 changed files with 3 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
fs/f2fs/gc.c
View File

@ -146,6 +146,9 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
struct victim_sel_policy *p)
{
/* SSR allocates in a segment unit */
if (p->alloc_mode == SSR)
return 1 << sbi->log_blocks_per_seg;
if (p->gc_mode == GC_GREEDY)
return (1 << sbi->log_blocks_per_seg) * p->ofs_unit;
else if (p->gc_mode == GC_CB)