[PATCH 17/25] lightnvm: pblk: use exact free block counter in RL

From: Matias BjÃrling
Date: Wed Dec 20 2017 - 12:25:26 EST

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From: Javier GonzÃlez <javier@xxxxxxxxxxxx>

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 GonzÃlez <javier@xxxxxxxxxxxx>
Signed-off-by: Hans Holmberg <hans.holmberg@xxxxxxxxxxxx>
Signed-off-by: Matias BjÃrling <m@xxxxxxxxxxx>
---
drivers/lightnvm/pblk-core.c | 19 +++++---------
drivers/lightnvm/pblk-init.c | 18 +++++++++++---
drivers/lightnvm/pblk-recovery.c | 4 +--
drivers/lightnvm/pblk-rl.c | 54 +++++++++++++++++++++++++++-------------
drivers/lightnvm/pblk-sysfs.c | 9 ++++---
drivers/lightnvm/pblk.h | 15 ++++++-----
6 files changed, 73 insertions(+), 46 deletions(-)

diff --git a/drivers/lightnvm/pblk-core.c b/drivers/lightnvm/pblk-core.c
index 9ebc60c..22cdafd 100644
--- a/drivers/lightnvm/pblk-core.c
+++ b/drivers/lightnvm/pblk-core.c
@@ -1145,7 +1145,7 @@ int pblk_line_recov_alloc(struct pblk *pblk, struct pblk_line *line)
}
spin_unlock(&l_mg->free_lock);

- pblk_rl_free_lines_dec(&pblk->rl, line);
+ pblk_rl_free_lines_dec(&pblk->rl, line, true);

if (!pblk_line_init_bb(pblk, line, 0)) {
list_add(&line->list, &l_mg->free_list);
@@ -1233,7 +1233,7 @@ static struct pblk_line *pblk_line_retry(struct pblk *pblk,
l_mg->data_line = retry_line;
spin_unlock(&l_mg->free_lock);

- pblk_rl_free_lines_dec(&pblk->rl, retry_line);
+ pblk_rl_free_lines_dec(&pblk->rl, line, false);

if (pblk_line_erase(pblk, retry_line))
goto retry;
@@ -1252,7 +1252,6 @@ struct pblk_line *pblk_line_get_first_data(struct pblk *pblk)
{
struct pblk_line_mgmt *l_mg = &pblk->l_mg;
struct pblk_line *line;
- int is_next = 0;

spin_lock(&l_mg->free_lock);
line = pblk_line_get(pblk);
@@ -1280,7 +1279,6 @@ struct pblk_line *pblk_line_get_first_data(struct pblk *pblk)
} else {
l_mg->data_next->seq_nr = l_mg->d_seq_nr++;
l_mg->data_next->type = PBLK_LINETYPE_DATA;
- is_next = 1;
}
spin_unlock(&l_mg->free_lock);

@@ -1290,10 +1288,6 @@ struct pblk_line *pblk_line_get_first_data(struct pblk *pblk)
return NULL;
}

- pblk_rl_free_lines_dec(&pblk->rl, line);
- if (is_next)
- pblk_rl_free_lines_dec(&pblk->rl, l_mg->data_next);
-
retry_setup:
if (!pblk_line_init_metadata(pblk, line, NULL)) {
line = pblk_line_retry(pblk, line);
@@ -1311,6 +1305,8 @@ struct pblk_line *pblk_line_get_first_data(struct pblk *pblk)
goto retry_setup;
}

+ pblk_rl_free_lines_dec(&pblk->rl, line, true);
+
return line;
}

@@ -1395,7 +1391,6 @@ struct pblk_line *pblk_line_replace_data(struct pblk *pblk)
struct pblk_line_mgmt *l_mg = &pblk->l_mg;
struct pblk_line *cur, *new = NULL;
unsigned int left_seblks;
- int is_next = 0;

cur = l_mg->data_line;
new = l_mg->data_next;
@@ -1444,6 +1439,8 @@ struct pblk_line *pblk_line_replace_data(struct pblk *pblk)
goto retry_setup;
}

+ pblk_rl_free_lines_dec(&pblk->rl, new, true);
+
/* Allocate next line for preparation */
spin_lock(&l_mg->free_lock);
l_mg->data_next = pblk_line_get(pblk);
@@ -1457,13 +1454,9 @@ struct pblk_line *pblk_line_replace_data(struct pblk *pblk)
} else {
l_mg->data_next->seq_nr = l_mg->d_seq_nr++;
l_mg->data_next->type = PBLK_LINETYPE_DATA;
- is_next = 1;
}
spin_unlock(&l_mg->free_lock);

- if (is_next)
- pblk_rl_free_lines_dec(&pblk->rl, l_mg->data_next);
-
out:
return new;
}
diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c
index 2af1b0a..e939f0a 100644
--- a/drivers/lightnvm/pblk-init.c
+++ b/drivers/lightnvm/pblk-init.c
@@ -579,22 +579,34 @@ static unsigned int calc_emeta_len(struct pblk *pblk)
static void pblk_set_provision(struct pblk *pblk, long nr_free_blks)
{
struct nvm_tgt_dev *dev = pblk->dev;
+ struct pblk_line_mgmt *l_mg = &pblk->l_mg;
+ struct pblk_line_meta *lm = &pblk->lm;
struct nvm_geo *geo = &dev->geo;
sector_t provisioned;
+ int sec_meta, blk_meta;

- pblk->over_pct = 20;
+ pblk->op = 20;

provisioned = nr_free_blks;
- provisioned *= (100 - pblk->over_pct);
+ provisioned *= (100 - pblk->op);
sector_div(provisioned, 100);

+ pblk->op_blks = nr_free_blks - provisioned;
+
/* Internally pblk manages all free blocks, but all calculations based
* on user capacity consider only provisioned blocks
*/
pblk->rl.total_blocks = nr_free_blks;
pblk->rl.nr_secs = nr_free_blks * geo->sec_per_chk;
- pblk->capacity = provisioned * geo->sec_per_chk;
+
+ /* 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);
+
+ pblk->capacity = (provisioned - blk_meta) * geo->sec_per_chk;
+
atomic_set(&pblk->rl.free_blocks, nr_free_blks);
+ atomic_set(&pblk->rl.free_user_blocks, nr_free_blks);
}

static int pblk_lines_alloc_metadata(struct pblk *pblk)
diff --git a/drivers/lightnvm/pblk-recovery.c b/drivers/lightnvm/pblk-recovery.c
index 39a2e19..fd38036 100644
--- a/drivers/lightnvm/pblk-recovery.c
+++ b/drivers/lightnvm/pblk-recovery.c
@@ -989,10 +989,8 @@ struct pblk_line *pblk_recov_l2p(struct pblk *pblk)
}
spin_unlock(&l_mg->free_lock);

- if (is_next) {
+ if (is_next)
pblk_line_erase(pblk, l_mg->data_next);
- pblk_rl_free_lines_dec(&pblk->rl, l_mg->data_next);
- }

out:
if (found_lines != recovered_lines)
diff --git a/drivers/lightnvm/pblk-rl.c b/drivers/lightnvm/pblk-rl.c
index abae31f..861572c 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)
@@ -174,17 +189,22 @@ 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;
+ /* 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->high = pblk->op_blks - blk_meta - lm->blk_per_line;
rl->high_pw = get_count_order(rl->high);

- rl->low = rl->total_blocks / PBLK_USER_LOW_THRS;
- if (rl->low < min_blocks)
- rl->low = min_blocks;
-
rl->rsv_blocks = min_blocks;

/* This will always be a power-of-2 */
diff --git a/drivers/lightnvm/pblk-sysfs.c b/drivers/lightnvm/pblk-sysfs.c
index 5cee2ac..620bab8 100644
--- a/drivers/lightnvm/pblk-sysfs.c
+++ b/drivers/lightnvm/pblk-sysfs.c
@@ -49,11 +49,12 @@ static ssize_t pblk_sysfs_luns_show(struct pblk *pblk, char *page)

static ssize_t pblk_sysfs_rate_limiter(struct pblk *pblk, char *page)
{
- int free_blocks, total_blocks;
+ int free_blocks, free_user_blocks, total_blocks;
int rb_user_max, rb_user_cnt;
int rb_gc_max, rb_gc_cnt, rb_budget, rb_state;

- free_blocks = atomic_read(&pblk->rl.free_blocks);
+ free_blocks = pblk_rl_nr_free_blks(&pblk->rl);
+ free_user_blocks = pblk_rl_nr_user_free_blks(&pblk->rl);
rb_user_max = pblk->rl.rb_user_max;
rb_user_cnt = atomic_read(&pblk->rl.rb_user_cnt);
rb_gc_max = pblk->rl.rb_gc_max;
@@ -64,16 +65,16 @@ static ssize_t pblk_sysfs_rate_limiter(struct pblk *pblk, char *page)
total_blocks = pblk->rl.total_blocks;

return snprintf(page, PAGE_SIZE,
- "u:%u/%u,gc:%u/%u(%u/%u)(stop:<%u,full:>%u,free:%d/%d)-%d\n",
+ "u:%u/%u,gc:%u/%u(%u)(stop:<%u,full:>%u,free:%d/%d/%d)-%d\n",
rb_user_cnt,
rb_user_max,
rb_gc_cnt,
rb_gc_max,
rb_state,
rb_budget,
- pblk->rl.low,
pblk->rl.high,
free_blocks,
+ free_user_blocks,
total_blocks,
READ_ONCE(pblk->rl.rb_user_active));
}
diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h
index 6f5fbd1..9a21d36 100644
--- a/drivers/lightnvm/pblk.h
+++ b/drivers/lightnvm/pblk.h
@@ -252,9 +252,6 @@ struct pblk_rl {
unsigned int high; /* Upper threshold for rate limiter (free run -
* user I/O rate limiter
*/
- unsigned int low; /* Lower threshold for rate limiter (user I/O
- * rate limiter - stall)
- */
unsigned int high_pw; /* High rounded up as a power of 2 */

#define PBLK_USER_HIGH_THRS 8 /* Begin write limit at 12% available blks */
@@ -288,7 +285,9 @@ struct pblk_rl {

unsigned long long nr_secs;
unsigned long total_blocks;
- atomic_t free_blocks;
+
+ atomic_t free_blocks; /* Total number of free blocks (+ OP) */
+ atomic_t free_user_blocks; /* Number of user free blocks (no OP) */
};

#define PBLK_LINE_EMPTY (~0U)
@@ -579,7 +578,9 @@ struct pblk {
*/

sector_t capacity; /* Device capacity when bad blocks are subtracted */
- int over_pct; /* Percentage of device used for over-provisioning */
+
+ int op; /* Percentage of device used for over-provisioning */
+ int op_blks; /* Number of blocks used for over-provisioning */

/* pblk provisioning values. Used by rate limiter */
struct pblk_rl rl;
@@ -839,6 +840,7 @@ void pblk_rl_free(struct pblk_rl *rl);
void pblk_rl_update_rates(struct pblk_rl *rl);
int pblk_rl_high_thrs(struct pblk_rl *rl);
unsigned long pblk_rl_nr_free_blks(struct pblk_rl *rl);
+unsigned long pblk_rl_nr_user_free_blks(struct pblk_rl *rl);
int pblk_rl_user_may_insert(struct pblk_rl *rl, int nr_entries);
void pblk_rl_inserted(struct pblk_rl *rl, int nr_entries);
void pblk_rl_user_in(struct pblk_rl *rl, int nr_entries);
@@ -847,7 +849,8 @@ void pblk_rl_gc_in(struct pblk_rl *rl, int nr_entries);
void pblk_rl_out(struct pblk_rl *rl, int nr_user, int nr_gc);
int pblk_rl_max_io(struct pblk_rl *rl);
void pblk_rl_free_lines_inc(struct pblk_rl *rl, struct pblk_line *line);
-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 pblk_rl_is_limit(struct pblk_rl *rl);

/*
--
2.9.3

Next message: Matias BjÃrling: "[PATCH 16/25] lightnvm: pblk: remove pblk_gc_stop"
Previous message: Matias BjÃrling: "[PATCH 18/25] lightnvm: set target over-provision on create ioctl"
In reply to: Matias BjÃrling: "[PATCH 18/25] lightnvm: set target over-provision on create ioctl"
Next in thread: Matias BjÃrling: "[PATCH 16/25] lightnvm: pblk: remove pblk_gc_stop"
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