From f3969ea78b5f54935474d49455cf9c4d6a1e107a Mon Sep 17 00:00:00 2001 From: Alexander Motin Date: Tue, 22 Jun 2021 19:35:23 -0400 Subject: Optimize small random numbers generation In all places except two spa_get_random() is used for small values, and the consumers do not require well seeded high quality values. Switch those two exceptions directly to random_get_pseudo_bytes() and optimize spa_get_random(), renaming it to random_in_range(), since it is not related to SPA or ZFS in general. On FreeBSD directly map random_in_range() to new prng32_bounded() KPI added in FreeBSD 13. On Linux and in user-space just reduce the type used to uint32_t to avoid more expensive 64bit division. Reviewed-by: Ryan Moeller Reviewed-by: Brian Behlendorf Signed-off-by: Alexander Motin Sponsored-By: iXsystems, Inc. Closes #12183 --- include/os/freebsd/spl/sys/random.h | 22 ++++++++++++++++++++++ include/os/linux/spl/sys/random.h | 15 +++++++++++++++ include/sys/spa.h | 1 - include/sys/zfs_context.h | 15 +++++++++++++++ 4 files changed, 52 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/os/freebsd/spl/sys/random.h b/include/os/freebsd/spl/sys/random.h index b3c9115f5..746275e53 100644 --- a/include/os/freebsd/spl/sys/random.h +++ b/include/os/freebsd/spl/sys/random.h @@ -30,6 +30,9 @@ #define _OPENSOLARIS_SYS_RANDOM_H_ #include_next +#if __FreeBSD_version >= 1300108 +#include +#endif static inline int random_get_bytes(uint8_t *p, size_t s) @@ -45,4 +48,23 @@ random_get_pseudo_bytes(uint8_t *p, size_t s) return (0); } +static inline uint32_t +random_in_range(uint32_t range) +{ +#if __FreeBSD_version >= 1300108 + return (prng32_bounded(range)); +#else + uint32_t r; + + ASSERT(range != 0); + + if (range == 1) + return (0); + + (void) random_get_pseudo_bytes((void *)&r, sizeof (r)); + + return (r % range); +#endif +} + #endif /* !_OPENSOLARIS_SYS_RANDOM_H_ */ diff --git a/include/os/linux/spl/sys/random.h b/include/os/linux/spl/sys/random.h index 1b8cb60d0..2c446e155 100644 --- a/include/os/linux/spl/sys/random.h +++ b/include/os/linux/spl/sys/random.h @@ -36,4 +36,19 @@ random_get_bytes(uint8_t *ptr, size_t len) extern int random_get_pseudo_bytes(uint8_t *ptr, size_t len); +static __inline__ uint32_t +random_in_range(uint32_t range) +{ + uint32_t r; + + ASSERT(range != 0); + + if (range == 1) + return (0); + + (void) random_get_pseudo_bytes((void *)&r, sizeof (r)); + + return (r % range); +} + #endif /* _SPL_RANDOM_H */ diff --git a/include/sys/spa.h b/include/sys/spa.h index 9dd47a1eb..532926e12 100644 --- a/include/sys/spa.h +++ b/include/sys/spa.h @@ -1086,7 +1086,6 @@ extern spa_t *spa_by_guid(uint64_t pool_guid, uint64_t device_guid); extern boolean_t spa_guid_exists(uint64_t pool_guid, uint64_t device_guid); extern char *spa_strdup(const char *); extern void spa_strfree(char *); -extern uint64_t spa_get_random(uint64_t range); extern uint64_t spa_generate_guid(spa_t *spa); extern void snprintf_blkptr(char *buf, size_t buflen, const blkptr_t *bp); extern void spa_freeze(spa_t *spa); diff --git a/include/sys/zfs_context.h b/include/sys/zfs_context.h index ffb20e1fe..dbeb323ba 100644 --- a/include/sys/zfs_context.h +++ b/include/sys/zfs_context.h @@ -640,6 +640,21 @@ extern int lowbit64(uint64_t i); extern int random_get_bytes(uint8_t *ptr, size_t len); extern int random_get_pseudo_bytes(uint8_t *ptr, size_t len); +static __inline__ uint32_t +random_in_range(uint32_t range) +{ + uint32_t r; + + ASSERT(range != 0); + + if (range == 1) + return (0); + + (void) random_get_pseudo_bytes((void *)&r, sizeof (r)); + + return (r % range); +} + extern void kernel_init(int mode); extern void kernel_fini(void); extern void random_init(void); -- cgit v1.2.3