From 21d2287119e843929c29fb1adbd271bde1fac7ae Mon Sep 17 00:00:00 2001 From: =?utf8?q?Javier=20Gonz=C3=A1lez?= Date: Fri, 13 Oct 2017 14:46:26 +0200 Subject: [PATCH] lightnvm: pblk: enable 1 LUN configuration MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Metadata I/Os are scheduled to minimize their impact on user data I/Os. When there are enough LUNs instantiated (i.e., enough bandwidth), it is easy to interleave metadata and data one after the other so that metadata I/Os are the ones being blocked and not vice-versa. We do this by calculating the distance between the I/Os in terms of the LUNs that are not in used, and selecting a free LUN that satisfies a the simple heuristic that metadata is scheduled behind. The per-LUN semaphores guarantee consistency. This works fine on >1 LUN configuration. However, when a single LUN is instantiated, this design leads to a deadlock, where metadata waits to be scheduled on a free LUN. This patch implements the 1 LUN case by simply scheduling the metadada I/O after the data I/O. In the process, we refactor the way a line is replaced to ensure that metadata writes are submitted after data writes in order to guarantee block sequentiality. Note that, since there is only one LUN, both I/Os will block each other by design. However, such configuration only pursues tight read latencies, not write bandwidth. Signed-off-by: Javier González Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe --- drivers/lightnvm/pblk-core.c | 17 ++++++++++------- drivers/lightnvm/pblk-init.c | 8 ++++++-- drivers/lightnvm/pblk-map.c | 21 ++++++++++++--------- drivers/lightnvm/pblk.h | 2 +- 4 files changed, 29 insertions(+), 19 deletions(-) diff --git a/drivers/lightnvm/pblk-core.c b/drivers/lightnvm/pblk-core.c index 0a41fb9..e38e918 100644 --- a/drivers/lightnvm/pblk-core.c +++ b/drivers/lightnvm/pblk-core.c @@ -1372,17 +1372,17 @@ void pblk_pipeline_stop(struct pblk *pblk) spin_unlock(&l_mg->free_lock); } -void pblk_line_replace_data(struct pblk *pblk) +struct pblk_line *pblk_line_replace_data(struct pblk *pblk) { struct pblk_line_mgmt *l_mg = &pblk->l_mg; - struct pblk_line *cur, *new; + struct pblk_line *cur, *new = NULL; unsigned int left_seblks; int is_next = 0; cur = l_mg->data_line; new = l_mg->data_next; if (!new) - return; + goto out; l_mg->data_line = new; spin_lock(&l_mg->free_lock); @@ -1390,7 +1390,7 @@ void pblk_line_replace_data(struct pblk *pblk) l_mg->data_line = NULL; l_mg->data_next = NULL; spin_unlock(&l_mg->free_lock); - return; + goto out; } pblk_line_setup_metadata(new, l_mg, &pblk->lm); @@ -1402,7 +1402,7 @@ retry_erase: /* If line is not fully erased, erase it */ if (atomic_read(&new->left_eblks)) { if (pblk_line_erase(pblk, new)) - return; + goto out; } else { io_schedule(); } @@ -1413,7 +1413,7 @@ retry_setup: if (!pblk_line_init_metadata(pblk, new, cur)) { new = pblk_line_retry(pblk, new); if (!new) - return; + goto out; goto retry_setup; } @@ -1421,7 +1421,7 @@ retry_setup: if (!pblk_line_init_bb(pblk, new, 1)) { new = pblk_line_retry(pblk, new); if (!new) - return; + goto out; goto retry_setup; } @@ -1445,6 +1445,9 @@ retry_setup: if (is_next) pblk_rl_free_lines_dec(&pblk->rl, l_mg->data_next); + +out: + return new; } void pblk_line_free(struct pblk *pblk, struct pblk_line *line) diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c index 3452764..3c37491 100644 --- a/drivers/lightnvm/pblk-init.c +++ b/drivers/lightnvm/pblk-init.c @@ -711,8 +711,12 @@ add_emeta_page: } lm->emeta_bb = geo->nr_luns - i; - lm->min_blk_line = 1 + DIV_ROUND_UP(lm->smeta_sec + lm->emeta_sec[0], - geo->sec_per_blk); + + lm->min_blk_line = 1; + if (geo->nr_luns > 1) + lm->min_blk_line += DIV_ROUND_UP(lm->smeta_sec + + lm->emeta_sec[0], geo->sec_per_blk); + if (lm->min_blk_line > lm->blk_per_line) { pr_err("pblk: config. not supported. Min. LUN in line:%d\n", lm->blk_per_line); diff --git a/drivers/lightnvm/pblk-map.c b/drivers/lightnvm/pblk-map.c index fddb924..3bc4c94 100644 --- a/drivers/lightnvm/pblk-map.c +++ b/drivers/lightnvm/pblk-map.c @@ -25,13 +25,23 @@ static void pblk_map_page_data(struct pblk *pblk, unsigned int sentry, unsigned int valid_secs) { struct pblk_line *line = pblk_line_get_data(pblk); - struct pblk_emeta *emeta = line->emeta; + struct pblk_emeta *emeta; struct pblk_w_ctx *w_ctx; - __le64 *lba_list = emeta_to_lbas(pblk, emeta->buf); + __le64 *lba_list; u64 paddr; int nr_secs = pblk->min_write_pgs; int i; + if (pblk_line_is_full(line)) { + struct pblk_line *prev_line = line; + + line = pblk_line_replace_data(pblk); + pblk_line_close_meta(pblk, prev_line); + } + + emeta = line->emeta; + lba_list = emeta_to_lbas(pblk, emeta->buf); + paddr = pblk_alloc_page(pblk, line, nr_secs); for (i = 0; i < nr_secs; i++, paddr++) { @@ -60,13 +70,6 @@ static void pblk_map_page_data(struct pblk *pblk, unsigned int sentry, } } - if (pblk_line_is_full(line)) { - struct pblk_line *prev_line = line; - - pblk_line_replace_data(pblk); - pblk_line_close_meta(pblk, prev_line); - } - pblk_down_rq(pblk, ppa_list, nr_secs, lun_bitmap); } diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h index e470437..191b1ec 100644 --- a/drivers/lightnvm/pblk.h +++ b/drivers/lightnvm/pblk.h @@ -719,7 +719,7 @@ struct bio *pblk_bio_map_addr(struct pblk *pblk, void *data, int alloc_type, gfp_t gfp_mask); struct pblk_line *pblk_line_get(struct pblk *pblk); struct pblk_line *pblk_line_get_first_data(struct pblk *pblk); -void pblk_line_replace_data(struct pblk *pblk); +struct pblk_line *pblk_line_replace_data(struct pblk *pblk); int pblk_line_recov_alloc(struct pblk *pblk, struct pblk_line *line); void pblk_line_recov_close(struct pblk *pblk, struct pblk_line *line); struct pblk_line *pblk_line_get_data(struct pblk *pblk); -- 2.7.4