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| 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.h | |
| parent | 1e82123da6a4c6019ef03bcd47e4b3dc18dd136e (diff) | |
| download | linux-21d2287119e843929c29fb1adbd271bde1fac7ae.tar.bz2 | |
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.h')
| -rw-r--r-- | drivers/lightnvm/pblk.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h index e4704373398b..191b1ec0627b 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); |