diff options
| author | Mike Snitzer <snitzer@kernel.org> | 2023-03-27 13:59:25 -0400 |
|---|---|---|
| committer | Mike Snitzer <snitzer@kernel.org> | 2023-03-30 15:57:51 -0400 |
| commit | 0bac3f2f28b87b520e50a196c42409485acfe5cf (patch) | |
| tree | 9b284a765f4e18da335e78af8be01d87c61de3c3 | |
| parent | 3f8d3f5432078a558151e27230e20bcf93c23ffe (diff) | |
dm: add dm_num_hash_locks()
Simple helper to use when DM core code needs to appropriately size,
based on num_online_cpus(), its data structures that split locks.
dm_num_hash_locks() rounds up num_online_cpus() to next power of 2
but caps return at DM_HASH_LOCKS_MAX (64).
This heuristic may evolve as warranted, but as-is it will serve as a
more informed basis for sizing the sharded lock structs in dm-bufio's
dm_buffer_cache (buffer_trees) and dm-bio-prison-v1's dm_bio_prison
(prison_regions).
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
| -rw-r--r-- | drivers/md/dm.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/md/dm.h b/drivers/md/dm.h index 22eaed188907..a1a5defddb07 100644 --- a/drivers/md/dm.h +++ b/drivers/md/dm.h @@ -20,6 +20,7 @@ #include <linux/completion.h> #include <linux/kobject.h> #include <linux/refcount.h> +#include <linux/log2.h> #include "dm-stats.h" @@ -228,4 +229,13 @@ void dm_free_md_mempools(struct dm_md_mempools *pools); */ unsigned int dm_get_reserved_bio_based_ios(void); +#define DM_HASH_LOCKS_MAX 64 + +static inline unsigned int dm_num_hash_locks(void) +{ + unsigned int num_locks = roundup_pow_of_two(num_online_cpus()); + + return min_t(unsigned int, num_locks, DM_HASH_LOCKS_MAX); +} + #endif |