diff options
| author | Javier González <javier@cnexlabs.com> | 2017-10-13 14:46:26 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2017-10-13 08:34:57 -0600 |
| commit | 21d2287119e843929c29fb1adbd271bde1fac7ae (patch) | |
| tree | aeb579a033c1e6d5d91dc8db71b36a8e51399c6b /drivers/lightnvm/pblk-init.c | |
| parent | 1e82123da6a4c6019ef03bcd47e4b3dc18dd136e (diff) | |
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-init.c')
| -rw-r--r-- | drivers/lightnvm/pblk-init.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c index 34527646c01b..3c3749186053 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); |