diff options
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/damon.h | 28 |
1 files changed, 21 insertions, 7 deletions
diff --git a/include/linux/damon.h b/include/linux/damon.h index c7a31572689b..4d4f031bcb45 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -8,23 +8,18 @@ #ifndef _DAMON_H_ #define _DAMON_H_ +#include <linux/math64.h> #include <linux/memcontrol.h> #include <linux/mutex.h> +#include <linux/prandom.h> #include <linux/time64.h> #include <linux/types.h> -#include <linux/random.h> /* Minimal region size. Every damon_region is aligned by this. */ #define DAMON_MIN_REGION_SZ PAGE_SIZE /* Max priority score for DAMON-based operation schemes */ #define DAMOS_MAX_SCORE (99) -/* Get a random number in [l, r) */ -static inline unsigned long damon_rand(unsigned long l, unsigned long r) -{ - return l + get_random_u32_below(r - l); -} - /** * struct damon_addr_range - Represents an address region of [@start, @end). * @start: Start address of the region (inclusive). @@ -859,8 +854,27 @@ struct damon_ctx { struct list_head adaptive_targets; struct list_head schemes; + + /* Per-ctx PRNG state for damon_rand(); kdamond is the sole consumer. */ + struct rnd_state rnd_state; }; +/* Get a random number in [@l, @r) using @ctx's lockless PRNG. */ +static inline unsigned long damon_rand(struct damon_ctx *ctx, + unsigned long l, unsigned long r) +{ + unsigned long span = r - l; + u64 rnd; + + if (span <= U32_MAX) { + rnd = prandom_u32_state(&ctx->rnd_state); + return l + (unsigned long)((rnd * span) >> 32); + } + rnd = ((u64)prandom_u32_state(&ctx->rnd_state) << 32) | + prandom_u32_state(&ctx->rnd_state); + return l + mul_u64_u64_shr(rnd, span, 64); +} + static inline struct damon_region *damon_next_region(struct damon_region *r) { return container_of(r->list.next, struct damon_region, list); |