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| author | Javier González <javier@cnexlabs.com> | 2017-10-13 15:46:26 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2017-10-13 17:34:57 +0300 |
| commit | 21d2287119e843929c29fb1adbd271bde1fac7ae (patch) | |
| tree | aeb579a033c1e6d5d91dc8db71b36a8e51399c6b /drivers/lightnvm/pblk-core.c | |
| parent | 1e82123da6a4c6019ef03bcd47e4b3dc18dd136e (diff) | |
| download | linux-21d2287119e843929c29fb1adbd271bde1fac7ae.tar.xz | |
lightnvm: pblk: enable 1 LUN configuration
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 <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/lightnvm/pblk-core.c')
| -rw-r--r-- | drivers/lightnvm/pblk-core.c | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/drivers/lightnvm/pblk-core.c b/drivers/lightnvm/pblk-core.c index 0a41fb998d55..e38e91897246 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) |