From 1759415e630e5db0dd2390df9f94892cbfb9a8a2 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Thu, 5 May 2011 15:23:54 -0500 Subject: [PATCH] slub: Remove CONFIG_CMPXCHG_LOCAL ifdeffery Remove the #ifdefs. This means that the irqsafe_cpu_cmpxchg_double() is used everywhere. There may be performance implications since: A. We now have to manage a transaction ID for all arches B. The interrupt holdoff for arches not supporting CONFIG_CMPXCHG_LOCAL is reduced to a very short irqoff section. There are no multiple irqoff/irqon sequences as a result of this change. Even in the fallback case we only have to do one disable and enable like before. Signed-off-by: Christoph Lameter Signed-off-by: Pekka Enberg --- include/linux/slub_def.h | 2 -- mm/slub.c | 56 ---------------------------------------- 2 files changed, 58 deletions(-) diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h index 45ca123e8002..ca0c076b2374 100644 --- a/include/linux/slub_def.h +++ b/include/linux/slub_def.h @@ -37,9 +37,7 @@ enum stat_item { struct kmem_cache_cpu { void **freelist; /* Pointer to next available object */ -#ifdef CONFIG_CMPXCHG_LOCAL unsigned long tid; /* Globally unique transaction id */ -#endif struct page *page; /* The slab from which we are allocating */ int node; /* The node of the page (or -1 for debug) */ #ifdef CONFIG_SLUB_STATS diff --git a/mm/slub.c b/mm/slub.c index c952fac112e8..461199f019d6 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1551,7 +1551,6 @@ static void unfreeze_slab(struct kmem_cache *s, struct page *page, int tail) } } -#ifdef CONFIG_CMPXCHG_LOCAL #ifdef CONFIG_PREEMPT /* * Calculate the next globally unique transaction for disambiguiation @@ -1611,17 +1610,12 @@ static inline void note_cmpxchg_failure(const char *n, stat(s, CMPXCHG_DOUBLE_CPU_FAIL); } -#endif - void init_kmem_cache_cpus(struct kmem_cache *s) { -#ifdef CONFIG_CMPXCHG_LOCAL int cpu; for_each_possible_cpu(cpu) per_cpu_ptr(s->cpu_slab, cpu)->tid = init_tid(cpu); -#endif - } /* * Remove the cpu slab @@ -1654,9 +1648,7 @@ static void deactivate_slab(struct kmem_cache *s, struct kmem_cache_cpu *c) page->inuse--; } c->page = NULL; -#ifdef CONFIG_CMPXCHG_LOCAL c->tid = next_tid(c->tid); -#endif unfreeze_slab(s, page, tail); } @@ -1791,7 +1783,6 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, { void **object; struct page *page; -#ifdef CONFIG_CMPXCHG_LOCAL unsigned long flags; local_irq_save(flags); @@ -1802,7 +1793,6 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, * pointer. */ c = this_cpu_ptr(s->cpu_slab); -#endif #endif /* We handle __GFP_ZERO in the caller */ @@ -1831,10 +1821,8 @@ load_freelist: unlock_out: slab_unlock(page); -#ifdef CONFIG_CMPXCHG_LOCAL c->tid = next_tid(c->tid); local_irq_restore(flags); -#endif stat(s, ALLOC_SLOWPATH); return object; @@ -1873,9 +1861,7 @@ load_from_page: } if (!(gfpflags & __GFP_NOWARN) && printk_ratelimit()) slab_out_of_memory(s, gfpflags, node); -#ifdef CONFIG_CMPXCHG_LOCAL local_irq_restore(flags); -#endif return NULL; debug: if (!alloc_debug_processing(s, page, object, addr)) @@ -1902,20 +1888,12 @@ static __always_inline void *slab_alloc(struct kmem_cache *s, { void **object; struct kmem_cache_cpu *c; -#ifdef CONFIG_CMPXCHG_LOCAL unsigned long tid; -#else - unsigned long flags; -#endif if (slab_pre_alloc_hook(s, gfpflags)) return NULL; -#ifndef CONFIG_CMPXCHG_LOCAL - local_irq_save(flags); -#else redo: -#endif /* * Must read kmem_cache cpu data via this cpu ptr. Preemption is @@ -1925,7 +1903,6 @@ redo: */ c = __this_cpu_ptr(s->cpu_slab); -#ifdef CONFIG_CMPXCHG_LOCAL /* * The transaction ids are globally unique per cpu and per operation on * a per cpu queue. Thus they can be guarantee that the cmpxchg_double @@ -1934,7 +1911,6 @@ redo: */ tid = c->tid; barrier(); -#endif object = c->freelist; if (unlikely(!object || !node_match(c, node))) @@ -1942,7 +1918,6 @@ redo: object = __slab_alloc(s, gfpflags, node, addr, c); else { -#ifdef CONFIG_CMPXCHG_LOCAL /* * The cmpxchg will only match if there was no additonal * operation and if we are on the right processor. @@ -1963,16 +1938,9 @@ redo: note_cmpxchg_failure("slab_alloc", s, tid); goto redo; } -#else - c->freelist = get_freepointer(s, object); -#endif stat(s, ALLOC_FASTPATH); } -#ifndef CONFIG_CMPXCHG_LOCAL - local_irq_restore(flags); -#endif - if (unlikely(gfpflags & __GFP_ZERO) && object) memset(object, 0, s->objsize); @@ -2049,11 +2017,9 @@ static void __slab_free(struct kmem_cache *s, struct page *page, { void *prior; void **object = (void *)x; -#ifdef CONFIG_CMPXCHG_LOCAL unsigned long flags; local_irq_save(flags); -#endif slab_lock(page); stat(s, FREE_SLOWPATH); @@ -2084,9 +2050,7 @@ static void __slab_free(struct kmem_cache *s, struct page *page, out_unlock: slab_unlock(page); -#ifdef CONFIG_CMPXCHG_LOCAL local_irq_restore(flags); -#endif return; slab_empty: @@ -2098,9 +2062,7 @@ slab_empty: stat(s, FREE_REMOVE_PARTIAL); } slab_unlock(page); -#ifdef CONFIG_CMPXCHG_LOCAL local_irq_restore(flags); -#endif stat(s, FREE_SLAB); discard_slab(s, page); } @@ -2121,20 +2083,11 @@ static __always_inline void slab_free(struct kmem_cache *s, { void **object = (void *)x; struct kmem_cache_cpu *c; -#ifdef CONFIG_CMPXCHG_LOCAL unsigned long tid; -#else - unsigned long flags; -#endif slab_free_hook(s, x); -#ifndef CONFIG_CMPXCHG_LOCAL - local_irq_save(flags); - -#else redo: -#endif /* * Determine the currently cpus per cpu slab. @@ -2144,15 +2097,12 @@ redo: */ c = __this_cpu_ptr(s->cpu_slab); -#ifdef CONFIG_CMPXCHG_LOCAL tid = c->tid; barrier(); -#endif if (likely(page == c->page && c->node != NUMA_NO_NODE)) { set_freepointer(s, object, c->freelist); -#ifdef CONFIG_CMPXCHG_LOCAL if (unlikely(!this_cpu_cmpxchg_double( s->cpu_slab->freelist, s->cpu_slab->tid, c->freelist, tid, @@ -2161,16 +2111,10 @@ redo: note_cmpxchg_failure("slab_free", s, tid); goto redo; } -#else - c->freelist = object; -#endif stat(s, FREE_FASTPATH); } else __slab_free(s, page, x, addr); -#ifndef CONFIG_CMPXCHG_LOCAL - local_irq_restore(flags); -#endif } void kmem_cache_free(struct kmem_cache *s, void *x) -- 2.39.2