From: Vlastimil Babka Date: Mon, 3 Feb 2025 09:28:50 +0000 (+0100) Subject: slab: don't batch kvfree_rcu() with SLUB_TINY X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=7f8471d79a1bc3bfd0c4b7734494479d53447366;p=users%2Fjedix%2Flinux-maple.git slab: don't batch kvfree_rcu() with SLUB_TINY kvfree_rcu() is batched for better performance except on TINY_RCU, which is a simple implementation for small UP systems. Similarly SLUB_TINY is an option intended for small systems, whether or not used together with TINY_RCU. In case SLUB_TINY is used with !TINY_RCU, it makes arguably sense to not do the batching and limit the memory footprint. It's also suboptimal to have RCU-specific #ifdefs in slab code. With that, add CONFIG_KVFREE_RCU_BATCHED to determine whether batching kvfree_rcu() implementation is used. It is not set by a user prompt, but enabled by default and disabled in case TINY_RCU or SLUB_TINY are enabled. Use the new config for #ifdef's in slab code and extend their scope to cover all code used by the batched kvfree_rcu(). For example there's no need to perform kvfree_rcu_init() if the batching is disabled. Reviewed-by: Uladzislau Rezki (Sony) Reviewed-by: Joel Fernandes (Google) Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Tested-by: Paul E. McKenney Signed-off-by: Vlastimil Babka --- diff --git a/include/linux/slab.h b/include/linux/slab.h index ef840cab8336..3b03b31831a9 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -1086,7 +1086,7 @@ extern void kvfree_sensitive(const void *addr, size_t len); unsigned int kmem_cache_size(struct kmem_cache *s); -#ifdef CONFIG_TINY_RCU +#ifndef CONFIG_KVFREE_RCU_BATCHED static inline void kvfree_rcu_barrier(void) { rcu_barrier(); diff --git a/mm/Kconfig b/mm/Kconfig index 4a4e7b63d30a..d3fb3762887b 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -195,6 +195,10 @@ menu "Slab allocator options" config SLUB def_bool y +config KVFREE_RCU_BATCHED + def_bool y + depends on !SLUB_TINY && !TINY_RCU + config SLUB_TINY bool "Configure for minimal memory footprint" depends on EXPERT diff --git a/mm/slab_common.c b/mm/slab_common.c index 6438a38aa5dc..46d0a4cd33b5 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1284,7 +1284,7 @@ EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); EXPORT_TRACEPOINT_SYMBOL(kfree); EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free); -#ifdef CONFIG_TINY_RCU +#ifndef CONFIG_KVFREE_RCU_BATCHED void kvfree_call_rcu(struct rcu_head *head, void *ptr) { @@ -1301,7 +1301,11 @@ void kvfree_call_rcu(struct rcu_head *head, void *ptr) } EXPORT_SYMBOL_GPL(kvfree_call_rcu); -#endif +void __init kvfree_rcu_init(void) +{ +} + +#else /* CONFIG_KVFREE_RCU_BATCHED */ /* * This rcu parameter is runtime-read-only. It reflects @@ -1879,8 +1883,6 @@ add_ptr_to_bulk_krc_lock(struct kfree_rcu_cpu **krcp, return true; } -#if !defined(CONFIG_TINY_RCU) - static enum hrtimer_restart schedule_page_work_fn(struct hrtimer *t) { @@ -2089,8 +2091,6 @@ void kvfree_rcu_barrier(void) } EXPORT_SYMBOL_GPL(kvfree_rcu_barrier); -#endif /* #if !defined(CONFIG_TINY_RCU) */ - static unsigned long kfree_rcu_shrink_count(struct shrinker *shrink, struct shrink_control *sc) { @@ -2180,3 +2180,6 @@ void __init kvfree_rcu_init(void) shrinker_register(kfree_rcu_shrinker); } + +#endif /* CONFIG_KVFREE_RCU_BATCHED */ +