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Date: Mon, 1 May 2017 23:37:52 +0800
From: Wei Yang <richard.weiyang@...il.com>
To: unlisted-recipients:; (no To-header on input)
Cc: cl@...ux.com, penberg@...nel.org, rientjes@...gle.com,
iamjoonsoo.kim@....com, akpm@...ux-foundation.org,
linux-mm@...ck.org, linux-kernel@...r.kernel.org,
Wei Yang <richard.weiyang@...il.com>
Subject: Re: [PATCH 3/3] mm/slub: wrap kmem_cache->cpu_partial in config
CONFIG_SLUB_CPU_PARTIAL
On Sun, Apr 30, 2017 at 07:31:52PM +0800, Wei Yang wrote:
>kmem_cache->cpu_partial is just used when CONFIG_SLUB_CPU_PARTIAL is set,
>so wrap it with config CONFIG_SLUB_CPU_PARTIAL will save some space
>on 32bit arch.
>
>This patch wrap kmem_cache->cpu_partial in config CONFIG_SLUB_CPU_PARTIAL
>and wrap its sysfs too.
>
>Signed-off-by: Wei Yang <richard.weiyang@...il.com>
>---
> include/linux/slub_def.h | 2 ++
> mm/slub.c | 72 +++++++++++++++++++++++++++++-------------------
> 2 files changed, 46 insertions(+), 28 deletions(-)
>
>diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
>index 0debd8df1a7d..477ab99800ed 100644
>--- a/include/linux/slub_def.h
>+++ b/include/linux/slub_def.h
>@@ -69,7 +69,9 @@ struct kmem_cache {
> int size; /* The size of an object including meta data */
> int object_size; /* The size of an object without meta data */
> int offset; /* Free pointer offset. */
>+#ifdef CONFIG_SLUB_CPU_PARTIAL
> int cpu_partial; /* Number of per cpu partial objects to keep around */
>+#endif
> struct kmem_cache_order_objects oo;
>
> /* Allocation and freeing of slabs */
>diff --git a/mm/slub.c b/mm/slub.c
>index fde499b6dad8..94978f27882a 100644
>--- a/mm/slub.c
>+++ b/mm/slub.c
>@@ -1829,7 +1829,10 @@ static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n,
> stat(s, CPU_PARTIAL_NODE);
> }
> if (!kmem_cache_has_cpu_partial(s)
>- || available > s->cpu_partial / 2)
>+#ifdef CONFIG_SLUB_CPU_PARTIAL
>+ || available > s->cpu_partial / 2
>+#endif
>+ )
> break;
Matthew,
I plan to change this one with the same idea you mentioned in previous reply.
While one special "technique" is how to name it.
How about name this one
slub_cpu_partial()
And rename the previous one
slub_percpu_partial()
This is really hard to say which one is better :-(
Not sure whether you have some insight in this.
>
> }
>@@ -3418,6 +3421,39 @@ static void set_min_partial(struct kmem_cache *s, unsigned long min)
> s->min_partial = min;
> }
>
>+static void set_cpu_partial(struct kmem_cache *s)
>+{
>+#ifdef CONFIG_SLUB_CPU_PARTIAL
>+ /*
>+ * cpu_partial determined the maximum number of objects kept in the
>+ * per cpu partial lists of a processor.
>+ *
>+ * Per cpu partial lists mainly contain slabs that just have one
>+ * object freed. If they are used for allocation then they can be
>+ * filled up again with minimal effort. The slab will never hit the
>+ * per node partial lists and therefore no locking will be required.
>+ *
>+ * This setting also determines
>+ *
>+ * A) The number of objects from per cpu partial slabs dumped to the
>+ * per node list when we reach the limit.
>+ * B) The number of objects in cpu partial slabs to extract from the
>+ * 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_has_cpu_partial(s))
>+ s->cpu_partial = 0;
>+ else if (s->size >= PAGE_SIZE)
>+ s->cpu_partial = 2;
>+ else if (s->size >= 1024)
>+ s->cpu_partial = 6;
>+ else if (s->size >= 256)
>+ s->cpu_partial = 13;
>+ else
>+ s->cpu_partial = 30;
>+#endif
>+}
>+
> /*
> * calculate_sizes() determines the order and the distribution of data within
> * a slab object.
>@@ -3576,33 +3612,7 @@ static int kmem_cache_open(struct kmem_cache *s, unsigned long flags)
> */
> set_min_partial(s, ilog2(s->size) / 2);
>
>- /*
>- * cpu_partial determined the maximum number of objects kept in the
>- * per cpu partial lists of a processor.
>- *
>- * Per cpu partial lists mainly contain slabs that just have one
>- * object freed. If they are used for allocation then they can be
>- * filled up again with minimal effort. The slab will never hit the
>- * per node partial lists and therefore no locking will be required.
>- *
>- * This setting also determines
>- *
>- * A) The number of objects from per cpu partial slabs dumped to the
>- * per node list when we reach the limit.
>- * B) The number of objects in cpu partial slabs to extract from the
>- * 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_has_cpu_partial(s))
>- s->cpu_partial = 0;
>- else if (s->size >= PAGE_SIZE)
>- s->cpu_partial = 2;
>- else if (s->size >= 1024)
>- s->cpu_partial = 6;
>- else if (s->size >= 256)
>- s->cpu_partial = 13;
>- else
>- s->cpu_partial = 30;
>+ set_cpu_partial(s);
>
> #ifdef CONFIG_NUMA
> s->remote_node_defrag_ratio = 1000;
>@@ -3989,7 +3999,9 @@ void __kmemcg_cache_deactivate(struct kmem_cache *s)
> * Disable empty slabs caching. Used to avoid pinning offline
> * memory cgroups by kmem pages that can be freed.
> */
>+#ifdef CONFIG_SLUB_CPU_PARTIAL
> s->cpu_partial = 0;
>+#endif
> s->min_partial = 0;
>
> /*
>@@ -4929,6 +4941,7 @@ static ssize_t min_partial_store(struct kmem_cache *s, const char *buf,
> }
> SLAB_ATTR(min_partial);
>
>+#ifdef CONFIG_SLUB_CPU_PARTIAL
> static ssize_t cpu_partial_show(struct kmem_cache *s, char *buf)
> {
> return sprintf(buf, "%u\n", s->cpu_partial);
>@@ -4951,6 +4964,7 @@ static ssize_t cpu_partial_store(struct kmem_cache *s, const char *buf,
> return length;
> }
> SLAB_ATTR(cpu_partial);
>+#endif
>
> static ssize_t ctor_show(struct kmem_cache *s, char *buf)
> {
>@@ -5363,7 +5377,9 @@ static struct attribute *slab_attrs[] = {
> &objs_per_slab_attr.attr,
> &order_attr.attr,
> &min_partial_attr.attr,
>+#ifdef CONFIG_SLUB_CPU_PARTIAL
> &cpu_partial_attr.attr,
>+#endif
> &objects_attr.attr,
> &objects_partial_attr.attr,
> &partial_attr.attr,
>--
>2.11.0
--
Wei Yang
Help you, Help me
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