lightnvm: pblk: use exact free block counter in RL
Until now, pblk's rate-limiter has used a heuristic to reserve space for
GC I/O given that the over-provision area was fixed.
In preparation for allowing to define the over-provision area on target
creation, define a dedicated free_block counter in the rate-limiter to
track the number of blocks being used for user data.
Signed-off-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Hans Holmberg <hans.holmberg@cnexlabs.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/drivers/lightnvm/pblk-rl.c b/drivers/lightnvm/pblk-rl.c
index dacc719..0d457b1 100644
--- a/drivers/lightnvm/pblk-rl.c
+++ b/drivers/lightnvm/pblk-rl.c
@@ -89,17 +89,15 @@ unsigned long pblk_rl_nr_free_blks(struct pblk_rl *rl)
return atomic_read(&rl->free_blocks);
}
-/*
- * We check for (i) the number of free blocks in the current LUN and (ii) the
- * total number of free blocks in the pblk instance. This is to even out the
- * number of free blocks on each LUN when GC kicks in.
- *
- * Only the total number of free blocks is used to configure the rate limiter.
- */
-void pblk_rl_update_rates(struct pblk_rl *rl)
+unsigned long pblk_rl_nr_user_free_blks(struct pblk_rl *rl)
+{
+ return atomic_read(&rl->free_user_blocks);
+}
+
+static void __pblk_rl_update_rates(struct pblk_rl *rl,
+ unsigned long free_blocks)
{
struct pblk *pblk = container_of(rl, struct pblk, rl);
- unsigned long free_blocks = pblk_rl_nr_free_blks(rl);
int max = rl->rb_budget;
if (free_blocks >= rl->high) {
@@ -132,20 +130,37 @@ void pblk_rl_update_rates(struct pblk_rl *rl)
pblk_gc_should_stop(pblk);
}
+void pblk_rl_update_rates(struct pblk_rl *rl)
+{
+ __pblk_rl_update_rates(rl, pblk_rl_nr_user_free_blks(rl));
+}
+
void pblk_rl_free_lines_inc(struct pblk_rl *rl, struct pblk_line *line)
{
int blk_in_line = atomic_read(&line->blk_in_line);
+ int free_blocks;
atomic_add(blk_in_line, &rl->free_blocks);
- pblk_rl_update_rates(rl);
+ free_blocks = atomic_add_return(blk_in_line, &rl->free_user_blocks);
+
+ __pblk_rl_update_rates(rl, free_blocks);
}
-void pblk_rl_free_lines_dec(struct pblk_rl *rl, struct pblk_line *line)
+void pblk_rl_free_lines_dec(struct pblk_rl *rl, struct pblk_line *line,
+ bool used)
{
int blk_in_line = atomic_read(&line->blk_in_line);
+ int free_blocks;
atomic_sub(blk_in_line, &rl->free_blocks);
- pblk_rl_update_rates(rl);
+
+ if (used)
+ free_blocks = atomic_sub_return(blk_in_line,
+ &rl->free_user_blocks);
+ else
+ free_blocks = atomic_read(&rl->free_user_blocks);
+
+ __pblk_rl_update_rates(rl, free_blocks);
}
int pblk_rl_high_thrs(struct pblk_rl *rl)
@@ -174,16 +189,21 @@ void pblk_rl_free(struct pblk_rl *rl)
void pblk_rl_init(struct pblk_rl *rl, int budget)
{
struct pblk *pblk = container_of(rl, struct pblk, rl);
+ struct nvm_tgt_dev *dev = pblk->dev;
+ struct nvm_geo *geo = &dev->geo;
+ struct pblk_line_mgmt *l_mg = &pblk->l_mg;
struct pblk_line_meta *lm = &pblk->lm;
int min_blocks = lm->blk_per_line * PBLK_GC_RSV_LINE;
+ int sec_meta, blk_meta;
+
unsigned int rb_windows;
- rl->high = rl->total_blocks / PBLK_USER_HIGH_THRS;
- rl->high_pw = get_count_order(rl->high);
+ /* Consider sectors used for metadata */
+ sec_meta = (lm->smeta_sec + lm->emeta_sec[0]) * l_mg->nr_free_lines;
+ blk_meta = DIV_ROUND_UP(sec_meta, geo->sec_per_chk);
- rl->low = rl->total_blocks / PBLK_USER_LOW_THRS;
- if (rl->low < min_blocks)
- rl->low = min_blocks;
+ rl->high = pblk->op_blks - blk_meta - lm->blk_per_line;
+ rl->high_pw = get_count_order(rl->high);
rl->rsv_blocks = min_blocks;