On Thu, Jun 20, 2013 at 10:50:56AM +0900, Joonsoo Kim wrote: >On Wed, Jun 19, 2013 at 02:29:29PM +0000, Christoph Lameter wrote: >> On Wed, 19 Jun 2013, Joonsoo Kim wrote: >> >> > How about maintaining cpu_partial when !CONFIG_SLUB_CPU_PARTIAL? >> > It makes code less churn and doesn't have much overhead. >> > At bottom, my implementation with cpu_partial is attached. It uses less '#ifdef'. >> >> Looks good. I am fine with it. >> >> Acked-by: Christoph Lameter <cl@xxxxxxxxx> > >Thanks! > >Hello, Pekka. >I attach a right formatted patch with acked by Christoph and >signed off by me. > >It is based on v3.10-rc6 and top of a patch >"slub: do not put a slab to cpu partial list when cpu_partial is 0". > >> >> -- >> To unsubscribe, send a message with 'unsubscribe linux-mm' in >> the body to majordomo@xxxxxxxxx. For more info on Linux MM, >> see: http://www.linux-mm.org/ . >> Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> > > >-----------------8<----------------------------------------------- >>From a3257adcff89fd89a7ecb26c1247eec511302807 Mon Sep 17 00:00:00 2001 >From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> >Date: Wed, 19 Jun 2013 14:05:52 +0900 >Subject: [PATCH] slub: Make cpu partial slab support configurable > >cpu partial support can introduce level of indeterminism that is not >wanted in certain context (like a realtime kernel). Make it configurable. > >This patch is based on Christoph Lameter's >"slub: Make cpu partial slab support configurable V2". > As you know, actually cpu_partial is the maximum number of objects kept in the per cpu slab and cpu partial lists of a processor instead of just the maximum number of objects kept in cpu partial lists of a processor. The allocation will always fallback to slow path if not config SLUB_CPU_PARTIAL, whether it will lead to more latency? Regards, Wanpeng Li >Acked-by: Christoph Lameter <cl@xxxxxxxxx> >Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> > >diff --git a/init/Kconfig b/init/Kconfig >index 2d9b831..a7ec1ec 100644 >--- a/init/Kconfig >+++ b/init/Kconfig >@@ -1559,6 +1559,17 @@ config SLOB > > endchoice > >+config SLUB_CPU_PARTIAL >+ default y >+ depends on SLUB >+ bool "SLUB per cpu partial cache" >+ help >+ Per cpu partial caches accellerate objects allocation and freeing >+ that is local to a processor at the price of more indeterminism >+ in the latency of the free. On overflow these caches will be cleared >+ which requires the taking of locks that may cause latency spikes. >+ Typically one would choose no for a realtime system. >+ > config MMAP_ALLOW_UNINITIALIZED > bool "Allow mmapped anonymous memory to be uninitialized" > depends on EXPERT && !MMU >diff --git a/mm/slub.c b/mm/slub.c >index 7033b4f..a670d22 100644 >--- a/mm/slub.c >+++ b/mm/slub.c >@@ -123,6 +123,15 @@ static inline int kmem_cache_debug(struct kmem_cache *s) > #endif > } > >+static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s) >+{ >+#ifdef CONFIG_SLUB_CPU_PARTIAL >+ return !kmem_cache_debug(s); >+#else >+ return false; >+#endif >+} >+ > /* > * Issues still to be resolved: > * >@@ -1573,7 +1582,8 @@ static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n, > put_cpu_partial(s, page, 0); > stat(s, CPU_PARTIAL_NODE); > } >- if (kmem_cache_debug(s) || available > s->cpu_partial / 2) >+ if (!kmem_cache_has_cpu_partial(s) >+ || available > s->cpu_partial / 2) > break; > > } >@@ -1884,6 +1894,7 @@ redo: > static void unfreeze_partials(struct kmem_cache *s, > struct kmem_cache_cpu *c) > { >+#ifdef CONFIG_SLUB_CPU_PARTIAL > struct kmem_cache_node *n = NULL, *n2 = NULL; > struct page *page, *discard_page = NULL; > >@@ -1938,6 +1949,7 @@ static void unfreeze_partials(struct kmem_cache *s, > discard_slab(s, page); > stat(s, FREE_SLAB); > } >+#endif > } > > /* >@@ -1951,6 +1963,7 @@ static void unfreeze_partials(struct kmem_cache *s, > */ > static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) > { >+#ifdef CONFIG_SLUB_CPU_PARTIAL > struct page *oldpage; > int pages; > int pobjects; >@@ -1990,6 +2003,7 @@ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) > page->next = oldpage; > > } while (this_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page) != oldpage); >+#endif > } > > static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c) >@@ -2498,7 +2512,7 @@ static void __slab_free(struct kmem_cache *s, struct page *page, > new.inuse--; > if ((!new.inuse || !prior) && !was_frozen) { > >- if (!kmem_cache_debug(s) && !prior) >+ if (kmem_cache_has_cpu_partial(s) && !prior) > > /* > * Slab was on no list before and will be partially empty >@@ -3062,7 +3076,7 @@ static int kmem_cache_open(struct kmem_cache *s, unsigned long flags) > * per node list when we run out of per cpu objects. We only fetch 50% > * to keep some capacity around for frees. > */ >- if (kmem_cache_debug(s)) >+ if (!kmem_cache_has_cpu_partial(s)) > s->cpu_partial = 0; > else if (s->size >= PAGE_SIZE) > s->cpu_partial = 2; >@@ -4459,7 +4473,7 @@ static ssize_t cpu_partial_store(struct kmem_cache *s, const char *buf, > err = strict_strtoul(buf, 10, &objects); > if (err) > return err; >- if (objects && kmem_cache_debug(s)) >+ if (objects && !kmem_cache_has_cpu_partial(s)) > return -EINVAL; > > s->cpu_partial = objects; >-- >1.7.9.5 > >-- >To unsubscribe, send a message with 'unsubscribe linux-mm' in >the body to majordomo@xxxxxxxxx. For more info on Linux MM, >see: http://www.linux-mm.org/ . >Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>