From 3bcebc5bac0935d662f30d317e33ffa660bebf93 Mon Sep 17 00:00:00 2001 From: Hans Holmberg Date: Tue, 11 Dec 2018 20:16:13 +0100 Subject: [PATCH] lightnvm: pblk: set conservative threshold for user writes MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit In a worst-case scenario (random writes), OP% of sectors in each line will be invalid, and we will then need to move data out of 100/OP% lines to free a single line. So, to prevent the possibility of running out of lines, temporarily block user writes when there is less than 100/OP% free lines. Also ensure that pblk creation does not produce instances with insufficient over provisioning. Insufficient over-provising is not a problem on real hardware, but often an issue when running QEMU simulations (with few lines). 100 lines is enough to create a sane instance with the standard (11%) over provisioning. Signed-off-by: Hans Holmberg Reviewed-by: Javier González Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe --- drivers/lightnvm/pblk-init.c | 40 ++++++++++++++++++++++++++++-------- drivers/lightnvm/pblk-rl.c | 5 ++--- drivers/lightnvm/pblk.h | 12 ++++++++++- 3 files changed, 44 insertions(+), 13 deletions(-) diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c index 13822594647c..f083130d9920 100644 --- a/drivers/lightnvm/pblk-init.c +++ b/drivers/lightnvm/pblk-init.c @@ -635,7 +635,7 @@ static unsigned int calc_emeta_len(struct pblk *pblk) return (lm->emeta_len[1] + lm->emeta_len[2] + lm->emeta_len[3]); } -static void pblk_set_provision(struct pblk *pblk, long nr_free_blks) +static int pblk_set_provision(struct pblk *pblk, int nr_free_chks) { struct nvm_tgt_dev *dev = pblk->dev; struct pblk_line_mgmt *l_mg = &pblk->l_mg; @@ -643,23 +643,41 @@ static void pblk_set_provision(struct pblk *pblk, long nr_free_blks) struct nvm_geo *geo = &dev->geo; sector_t provisioned; int sec_meta, blk_meta; + int minimum; if (geo->op == NVM_TARGET_DEFAULT_OP) pblk->op = PBLK_DEFAULT_OP; else pblk->op = geo->op; - provisioned = nr_free_blks; + minimum = pblk_get_min_chks(pblk); + provisioned = nr_free_chks; provisioned *= (100 - pblk->op); sector_div(provisioned, 100); - pblk->op_blks = nr_free_blks - provisioned; + if ((nr_free_chks - provisioned) < minimum) { + if (geo->op != NVM_TARGET_DEFAULT_OP) { + pblk_err(pblk, "OP too small to create a sane instance\n"); + return -EINTR; + } + + /* If the user did not specify an OP value, and PBLK_DEFAULT_OP + * is not enough, calculate and set sane value + */ + + provisioned = nr_free_chks - minimum; + pblk->op = (100 * minimum) / nr_free_chks; + pblk_info(pblk, "Default OP insufficient, adjusting OP to %d\n", + pblk->op); + } + + pblk->op_blks = nr_free_chks - 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->clba; + pblk->rl.total_blocks = nr_free_chks; + pblk->rl.nr_secs = nr_free_chks * geo->clba; /* Consider sectors used for metadata */ sec_meta = (lm->smeta_sec + lm->emeta_sec[0]) * l_mg->nr_free_lines; @@ -667,8 +685,10 @@ static void pblk_set_provision(struct pblk *pblk, long nr_free_blks) pblk->capacity = (provisioned - blk_meta) * geo->clba; - atomic_set(&pblk->rl.free_blocks, nr_free_blks); - atomic_set(&pblk->rl.free_user_blocks, nr_free_blks); + atomic_set(&pblk->rl.free_blocks, nr_free_chks); + atomic_set(&pblk->rl.free_user_blocks, nr_free_chks); + + return 0; } static int pblk_setup_line_meta_chk(struct pblk *pblk, struct pblk_line *line, @@ -984,7 +1004,7 @@ static int pblk_lines_init(struct pblk *pblk) struct pblk_line_mgmt *l_mg = &pblk->l_mg; struct pblk_line *line; void *chunk_meta; - long nr_free_chks = 0; + int nr_free_chks = 0; int i, ret; ret = pblk_line_meta_init(pblk); @@ -1031,7 +1051,9 @@ static int pblk_lines_init(struct pblk *pblk) goto fail_free_lines; } - pblk_set_provision(pblk, nr_free_chks); + ret = pblk_set_provision(pblk, nr_free_chks); + if (ret) + goto fail_free_lines; vfree(chunk_meta); return 0; diff --git a/drivers/lightnvm/pblk-rl.c b/drivers/lightnvm/pblk-rl.c index db55a1c89997..76116d5f78e4 100644 --- a/drivers/lightnvm/pblk-rl.c +++ b/drivers/lightnvm/pblk-rl.c @@ -214,11 +214,10 @@ void pblk_rl_init(struct pblk_rl *rl, int budget) 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; + /* 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->clba); @@ -226,7 +225,7 @@ void pblk_rl_init(struct pblk_rl *rl, int budget) rl->high = pblk->op_blks - blk_meta - lm->blk_per_line; rl->high_pw = get_count_order(rl->high); - rl->rsv_blocks = min_blocks; + rl->rsv_blocks = pblk_get_min_chks(pblk); /* This will always be a power-of-2 */ rb_windows = budget / NVM_MAX_VLBA; diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h index f415aae600c8..e5b88a25d4d6 100644 --- a/drivers/lightnvm/pblk.h +++ b/drivers/lightnvm/pblk.h @@ -905,7 +905,6 @@ int pblk_recov_check_emeta(struct pblk *pblk, struct line_emeta *emeta); #define PBLK_GC_MAX_READERS 8 /* Max number of outstanding GC reader jobs */ #define PBLK_GC_RQ_QD 128 /* Queue depth for inflight GC requests */ #define PBLK_GC_L_QD 4 /* Queue depth for inflight GC lines */ -#define PBLK_GC_RSV_LINE 1 /* Reserved lines for GC */ int pblk_gc_init(struct pblk *pblk); void pblk_gc_exit(struct pblk *pblk, bool graceful); @@ -1370,4 +1369,15 @@ static inline char *pblk_disk_name(struct pblk *pblk) return disk->disk_name; } + +static inline unsigned int pblk_get_min_chks(struct pblk *pblk) +{ + struct pblk_line_meta *lm = &pblk->lm; + /* In a worst-case scenario every line will have OP invalid sectors. + * We will then need a minimum of 1/OP lines to free up a single line + */ + + return DIV_ROUND_UP(100, pblk->op) * lm->blk_per_line; + +} #endif /* PBLK_H_ */ -- 2.30.2