The decision whether to scan remote nodes is based on a 'random' number retrieved via get_cycles(). get_cycles() is about to be removed.
There is already prandom state in the code, so use that instead. Signed-off-by: Thomas Gleixner <[email protected]> Cc: Vlastimil Babka <[email protected]> Cc: [email protected] --- mm/slub.c | 37 +++++++++++++++++++++++-------------- 1 file changed, 23 insertions(+), 14 deletions(-) --- a/mm/slub.c +++ b/mm/slub.c @@ -3302,6 +3302,25 @@ static inline struct slab *alloc_slab_pa return slab; } +#if defined(CONFIG_SLAB_FREELIST_RANDOM) || defined(CONFIG_NUMA) +static DEFINE_PER_CPU(struct rnd_state, slab_rnd_state); + +static unsigned int slab_get_prandom_state(unsigned int limit) +{ + struct rnd_state *state; + unsigned int res; + + /* + * An interrupt or NMI handler might interrupt and change + * the state in the middle, but that's safe. + */ + state = &get_cpu_var(slab_rnd_state); + res = prandom_u32_state(state) % limit; + put_cpu_var(slab_rnd_state); + return res; +} +#endif + #ifdef CONFIG_SLAB_FREELIST_RANDOM /* Pre-initialize the random sequence cache */ static int init_cache_random_seq(struct kmem_cache *s) @@ -3365,8 +3384,6 @@ static void *next_freelist_entry(struct return (char *)start + idx; } -static DEFINE_PER_CPU(struct rnd_state, slab_rnd_state); - /* Shuffle the single linked freelist based on a random pre-computed sequence */ static bool shuffle_freelist(struct kmem_cache *s, struct slab *slab, bool allow_spin) @@ -3383,15 +3400,7 @@ static bool shuffle_freelist(struct kmem if (allow_spin) { pos = get_random_u32_below(freelist_count); } else { - struct rnd_state *state; - - /* - * An interrupt or NMI handler might interrupt and change - * the state in the middle, but that's safe. - */ - state = &get_cpu_var(slab_rnd_state); - pos = prandom_u32_state(state) % freelist_count; - put_cpu_var(slab_rnd_state); + pos = slab_get_prandom_state(freelist_count); } page_limit = slab->objects * s->size; @@ -3882,7 +3891,7 @@ static void *get_from_any_partial(struct * with available objects. */ if (!s->remote_node_defrag_ratio || - get_cycles() % 1024 > s->remote_node_defrag_ratio) + slab_get_prandom_state(1024) > s->remote_node_defrag_ratio) return NULL; do { @@ -7102,7 +7111,7 @@ static unsigned int /* see get_from_any_partial() for the defrag ratio description */ if (!s->remote_node_defrag_ratio || - get_cycles() % 1024 > s->remote_node_defrag_ratio) + slab_get_prandom_state(1024) > s->remote_node_defrag_ratio) return 0; do { @@ -8421,7 +8430,7 @@ void __init kmem_cache_init_late(void) flushwq = alloc_workqueue("slub_flushwq", WQ_MEM_RECLAIM | WQ_PERCPU, 0); WARN_ON(!flushwq); -#ifdef CONFIG_SLAB_FREELIST_RANDOM +#if defined(CONFIG_SLAB_FREELIST_RANDOM) || defined(CONFIG_NUMA) prandom_init_once(&slab_rnd_state); #endif }
