* [PATCH 1/3] mm/slub: pack red_left_pad with another int to save a word
2017-04-30 11:31 [PATCH 0/3] try to save some memory for kmem_cache in some cases Wei Yang
@ 2017-04-30 11:31 ` Wei Yang
2017-04-30 11:31 ` [PATCH 2/3] mm/slub: wrap cpu_slab->partial in CONFIG_SLUB_CPU_PARTIAL Wei Yang
` (2 subsequent siblings)
3 siblings, 0 replies; 11+ messages in thread
From: Wei Yang @ 2017-04-30 11:31 UTC (permalink / raw)
To: cl, penberg, rientjes, iamjoonsoo.kim, akpm
Cc: linux-mm, linux-kernel, Wei Yang
On 64bit arch, struct is 8-bytes aligned, so int will occupy a word if it
doesn't sits well.
This patch pack red_left_pad with reserved to save 8 bytes for struct
kmem_cache on a 64bit arch.
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
---
include/linux/slub_def.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 07ef550c6627..ec13aab32647 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -79,9 +79,9 @@ struct kmem_cache {
int inuse; /* Offset to metadata */
int align; /* Alignment */
int reserved; /* Reserved bytes at the end of slabs */
+ int red_left_pad; /* Left redzone padding size */
const char *name; /* Name (only for display!) */
struct list_head list; /* List of slab caches */
- int red_left_pad; /* Left redzone padding size */
#ifdef CONFIG_SYSFS
struct kobject kobj; /* For sysfs */
#endif
--
2.11.0
^ permalink raw reply related [flat|nested] 11+ messages in thread
* [PATCH 2/3] mm/slub: wrap cpu_slab->partial in CONFIG_SLUB_CPU_PARTIAL
2017-04-30 11:31 [PATCH 0/3] try to save some memory for kmem_cache in some cases Wei Yang
2017-04-30 11:31 ` [PATCH 1/3] mm/slub: pack red_left_pad with another int to save a word Wei Yang
@ 2017-04-30 11:31 ` Wei Yang
2017-05-01 2:41 ` Matthew Wilcox
2017-04-30 11:31 ` [PATCH 3/3] mm/slub: wrap kmem_cache->cpu_partial in config CONFIG_SLUB_CPU_PARTIAL Wei Yang
2017-04-30 21:22 ` [PATCH 0/3] try to save some memory for kmem_cache in some cases Christoph Lameter
3 siblings, 1 reply; 11+ messages in thread
From: Wei Yang @ 2017-04-30 11:31 UTC (permalink / raw)
To: cl, penberg, rientjes, iamjoonsoo.kim, akpm
Cc: linux-mm, linux-kernel, Wei Yang
cpu_slab's field partial is used when CONFIG_SLUB_CPU_PARTIAL is set, which
means we can save a pointer's space on each cpu for every slub item.
This patch wrap cpu_slab->partial in CONFIG_SLUB_CPU_PARTIAL and wrap its
sysfs too.
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
---
include/linux/slub_def.h | 2 ++
mm/slub.c | 16 +++++++++++++++-
2 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index ec13aab32647..0debd8df1a7d 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -41,7 +41,9 @@ struct kmem_cache_cpu {
void **freelist; /* Pointer to next available object */
unsigned long tid; /* Globally unique transaction id */
struct page *page; /* The slab from which we are allocating */
+#ifdef CONFIG_SLUB_CPU_PARTIAL
struct page *partial; /* Partially allocated frozen slabs */
+#endif
#ifdef CONFIG_SLUB_STATS
unsigned stat[NR_SLUB_STAT_ITEMS];
#endif
diff --git a/mm/slub.c b/mm/slub.c
index 7f4bc7027ed5..fde499b6dad8 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2302,7 +2302,11 @@ static bool has_cpu_slab(int cpu, void *info)
struct kmem_cache *s = info;
struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
- return c->page || c->partial;
+ return c->page
+#ifdef CONFIG_SLUB_CPU_PARTIAL
+ || c->partial
+#endif
+ ;
}
static void flush_all(struct kmem_cache *s)
@@ -2511,7 +2515,9 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
page = c->page;
if (!page)
goto new_slab;
+#ifdef CONFIG_SLUB_CPU_PARTIAL
redo:
+#endif
if (unlikely(!node_match(page, node))) {
int searchnode = node;
@@ -2568,6 +2574,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
new_slab:
+#ifdef CONFIG_SLUB_CPU_PARTIAL
if (c->partial) {
page = c->page = c->partial;
c->partial = page->next;
@@ -2575,6 +2582,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
c->freelist = NULL;
goto redo;
}
+#endif
freelist = new_slab_objects(s, gfpflags, node, &c);
@@ -4760,6 +4768,7 @@ static ssize_t show_slab_objects(struct kmem_cache *s,
total += x;
nodes[node] += x;
+#ifdef CONFIG_SLUB_CPU_PARTIAL
page = READ_ONCE(c->partial);
if (page) {
node = page_to_nid(page);
@@ -4772,6 +4781,7 @@ static ssize_t show_slab_objects(struct kmem_cache *s,
total += x;
nodes[node] += x;
}
+#endif
}
}
@@ -4980,6 +4990,7 @@ static ssize_t objects_partial_show(struct kmem_cache *s, char *buf)
}
SLAB_ATTR_RO(objects_partial);
+#ifdef CONFIG_SLUB_CPU_PARTIAL
static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
{
int objects = 0;
@@ -5010,6 +5021,7 @@ static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
return len + sprintf(buf + len, "\n");
}
SLAB_ATTR_RO(slabs_cpu_partial);
+#endif
static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
{
@@ -5364,7 +5376,9 @@ static struct attribute *slab_attrs[] = {
&destroy_by_rcu_attr.attr,
&shrink_attr.attr,
&reserved_attr.attr,
+#ifdef CONFIG_SLUB_CPU_PARTIAL
&slabs_cpu_partial_attr.attr,
+#endif
#ifdef CONFIG_SLUB_DEBUG
&total_objects_attr.attr,
&slabs_attr.attr,
--
2.11.0
^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [PATCH 2/3] mm/slub: wrap cpu_slab->partial in CONFIG_SLUB_CPU_PARTIAL
2017-04-30 11:31 ` [PATCH 2/3] mm/slub: wrap cpu_slab->partial in CONFIG_SLUB_CPU_PARTIAL Wei Yang
@ 2017-05-01 2:41 ` Matthew Wilcox
2017-05-01 7:39 ` Wei Yang
2017-05-01 8:20 ` Wei Yang
0 siblings, 2 replies; 11+ messages in thread
From: Matthew Wilcox @ 2017-05-01 2:41 UTC (permalink / raw)
To: Wei Yang
Cc: cl, penberg, rientjes, iamjoonsoo.kim, akpm, linux-mm, linux-kernel
On Sun, Apr 30, 2017 at 07:31:51PM +0800, Wei Yang wrote:
> @@ -2302,7 +2302,11 @@ static bool has_cpu_slab(int cpu, void *info)
> struct kmem_cache *s = info;
> struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
>
> - return c->page || c->partial;
> + return c->page
> +#ifdef CONFIG_SLUB_CPU_PARTIAL
> + || c->partial
> +#endif
> + ;
> }
No. No way. This is disgusting.
The right way to do this is to create an accessor like this:
#ifdef CONFIG_SLUB_CPU_PARTIAL
#define slub_cpu_partial(c) ((c)->partial)
#else
#define slub_cpu_partial(c) 0
#endif
And then the above becomes:
- return c->page || c->partial;
+ return c->page || slub_cpu_partial(c);
All the other ifdefs go away, apart from these two:
> @@ -4980,6 +4990,7 @@ static ssize_t objects_partial_show(struct kmem_cache *s, char *buf)
> }
> SLAB_ATTR_RO(objects_partial);
>
> +#ifdef CONFIG_SLUB_CPU_PARTIAL
> static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
> {
> int objects = 0;
> @@ -5010,6 +5021,7 @@ static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
> return len + sprintf(buf + len, "\n");
> }
> SLAB_ATTR_RO(slabs_cpu_partial);
> +#endif
>
> static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
> {
> @@ -5364,7 +5376,9 @@ static struct attribute *slab_attrs[] = {
> &destroy_by_rcu_attr.attr,
> &shrink_attr.attr,
> &reserved_attr.attr,
> +#ifdef CONFIG_SLUB_CPU_PARTIAL
> &slabs_cpu_partial_attr.attr,
> +#endif
> #ifdef CONFIG_SLUB_DEBUG
> &total_objects_attr.attr,
> &slabs_attr.attr,
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 2/3] mm/slub: wrap cpu_slab->partial in CONFIG_SLUB_CPU_PARTIAL
2017-05-01 2:41 ` Matthew Wilcox
@ 2017-05-01 7:39 ` Wei Yang
2017-05-01 8:20 ` Wei Yang
1 sibling, 0 replies; 11+ messages in thread
From: Wei Yang @ 2017-05-01 7:39 UTC (permalink / raw)
To: Matthew Wilcox
Cc: Wei Yang, cl, penberg, rientjes, iamjoonsoo.kim, akpm, linux-mm,
linux-kernel
[-- Attachment #1: Type: text/plain, Size: 2151 bytes --]
On Sun, Apr 30, 2017 at 07:41:03PM -0700, Matthew Wilcox wrote:
>On Sun, Apr 30, 2017 at 07:31:51PM +0800, Wei Yang wrote:
>> @@ -2302,7 +2302,11 @@ static bool has_cpu_slab(int cpu, void *info)
>> struct kmem_cache *s = info;
>> struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
>>
>> - return c->page || c->partial;
>> + return c->page
>> +#ifdef CONFIG_SLUB_CPU_PARTIAL
>> + || c->partial
>> +#endif
>> + ;
>> }
>
>No. No way. This is disgusting.
>
Thanks for your comment. I believe you are right.
>The right way to do this is to create an accessor like this:
>
>#ifdef CONFIG_SLUB_CPU_PARTIAL
>#define slub_cpu_partial(c) ((c)->partial)
>#else
>#define slub_cpu_partial(c) 0
Since partial is a pointer to a page, would this be more proper?
#define slub_cpu_partial(c) NULL
>#endif
>
>And then the above becomes:
>
>- return c->page || c->partial;
>+ return c->page || slub_cpu_partial(c);
>
>All the other ifdefs go away, apart from these two:
Looks most of the ifdefs could be replaced by this format, while not all of
them. For example, the sysfs entry.
I would form another version with your suggestion.
Welcome any other comments :-)
>
>> @@ -4980,6 +4990,7 @@ static ssize_t objects_partial_show(struct kmem_cache *s, char *buf)
>> }
>> SLAB_ATTR_RO(objects_partial);
>>
>> +#ifdef CONFIG_SLUB_CPU_PARTIAL
>> static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
>> {
>> int objects = 0;
>> @@ -5010,6 +5021,7 @@ static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
>> return len + sprintf(buf + len, "\n");
>> }
>> SLAB_ATTR_RO(slabs_cpu_partial);
>> +#endif
>>
>> static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
>> {
>> @@ -5364,7 +5376,9 @@ static struct attribute *slab_attrs[] = {
>> &destroy_by_rcu_attr.attr,
>> &shrink_attr.attr,
>> &reserved_attr.attr,
>> +#ifdef CONFIG_SLUB_CPU_PARTIAL
>> &slabs_cpu_partial_attr.attr,
>> +#endif
>> #ifdef CONFIG_SLUB_DEBUG
>> &total_objects_attr.attr,
>> &slabs_attr.attr,
--
Wei Yang
Help you, Help me
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 819 bytes --]
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 2/3] mm/slub: wrap cpu_slab->partial in CONFIG_SLUB_CPU_PARTIAL
2017-05-01 2:41 ` Matthew Wilcox
2017-05-01 7:39 ` Wei Yang
@ 2017-05-01 8:20 ` Wei Yang
2017-05-01 14:39 ` Matthew Wilcox
1 sibling, 1 reply; 11+ messages in thread
From: Wei Yang @ 2017-05-01 8:20 UTC (permalink / raw)
To: Matthew Wilcox
Cc: Wei Yang, cl, penberg, rientjes, iamjoonsoo.kim, akpm, linux-mm,
linux-kernel
[-- Attachment #1: Type: text/plain, Size: 2072 bytes --]
On Sun, Apr 30, 2017 at 07:41:03PM -0700, Matthew Wilcox wrote:
>On Sun, Apr 30, 2017 at 07:31:51PM +0800, Wei Yang wrote:
>> @@ -2302,7 +2302,11 @@ static bool has_cpu_slab(int cpu, void *info)
>> struct kmem_cache *s = info;
>> struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
>>
>> - return c->page || c->partial;
>> + return c->page
>> +#ifdef CONFIG_SLUB_CPU_PARTIAL
>> + || c->partial
>> +#endif
>> + ;
>> }
>
>No. No way. This is disgusting.
>
>The right way to do this is to create an accessor like this:
>
>#ifdef CONFIG_SLUB_CPU_PARTIAL
>#define slub_cpu_partial(c) ((c)->partial)
>#else
>#define slub_cpu_partial(c) 0
>#endif
>
>And then the above becomes:
>
>- return c->page || c->partial;
>+ return c->page || slub_cpu_partial(c);
>
>All the other ifdefs go away, apart from these two:
>
Matthew
I have tried to replace the code with slub_cpu_partial(), it works fine on
most of cases except two:
1. slub_cpu_partial(c) = page->next;
2. page = READ_ONCE(slub_cpu_partial(c));
The sysfs part works fine.
So if you agree, I would leave these two parts as v1.
>> @@ -4980,6 +4990,7 @@ static ssize_t objects_partial_show(struct kmem_cache *s, char *buf)
>> }
>> SLAB_ATTR_RO(objects_partial);
>>
>> +#ifdef CONFIG_SLUB_CPU_PARTIAL
>> static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
>> {
>> int objects = 0;
>> @@ -5010,6 +5021,7 @@ static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
>> return len + sprintf(buf + len, "\n");
>> }
>> SLAB_ATTR_RO(slabs_cpu_partial);
>> +#endif
>>
>> static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
>> {
>> @@ -5364,7 +5376,9 @@ static struct attribute *slab_attrs[] = {
>> &destroy_by_rcu_attr.attr,
>> &shrink_attr.attr,
>> &reserved_attr.attr,
>> +#ifdef CONFIG_SLUB_CPU_PARTIAL
>> &slabs_cpu_partial_attr.attr,
>> +#endif
>> #ifdef CONFIG_SLUB_DEBUG
>> &total_objects_attr.attr,
>> &slabs_attr.attr,
--
Wei Yang
Help you, Help me
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 819 bytes --]
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 2/3] mm/slub: wrap cpu_slab->partial in CONFIG_SLUB_CPU_PARTIAL
2017-05-01 8:20 ` Wei Yang
@ 2017-05-01 14:39 ` Matthew Wilcox
2017-05-01 15:15 ` Wei Yang
0 siblings, 1 reply; 11+ messages in thread
From: Matthew Wilcox @ 2017-05-01 14:39 UTC (permalink / raw)
To: Wei Yang
Cc: cl, penberg, rientjes, iamjoonsoo.kim, akpm, linux-mm, linux-kernel
On Mon, May 01, 2017 at 04:20:05PM +0800, Wei Yang wrote:
> I have tried to replace the code with slub_cpu_partial(), it works fine on
> most of cases except two:
>
> 1. slub_cpu_partial(c) = page->next;
New accessor: slub_set_cpu_partial(c, p)
> 2. page = READ_ONCE(slub_cpu_partial(c));
OK, that one I haven't seen an existing pattern for yet.
slub_cpu_partial_read_once(c)?
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 2/3] mm/slub: wrap cpu_slab->partial in CONFIG_SLUB_CPU_PARTIAL
2017-05-01 14:39 ` Matthew Wilcox
@ 2017-05-01 15:15 ` Wei Yang
0 siblings, 0 replies; 11+ messages in thread
From: Wei Yang @ 2017-05-01 15:15 UTC (permalink / raw)
To: Matthew Wilcox
Cc: Wei Yang, cl, penberg, rientjes, iamjoonsoo.kim, akpm, linux-mm,
linux-kernel
[-- Attachment #1: Type: text/plain, Size: 542 bytes --]
On Mon, May 01, 2017 at 07:39:30AM -0700, Matthew Wilcox wrote:
>On Mon, May 01, 2017 at 04:20:05PM +0800, Wei Yang wrote:
>> I have tried to replace the code with slub_cpu_partial(), it works fine on
>> most of cases except two:
>>
>> 1. slub_cpu_partial(c) = page->next;
>
>New accessor: slub_set_cpu_partial(c, p)
>
>> 2. page = READ_ONCE(slub_cpu_partial(c));
>
>OK, that one I haven't seen an existing pattern for yet.
>slub_cpu_partial_read_once(c)?
Thanks~ You are really a genius.
--
Wei Yang
Help you, Help me
[-- Attachment #2: signature.asc --]
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^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH 3/3] mm/slub: wrap kmem_cache->cpu_partial in config CONFIG_SLUB_CPU_PARTIAL
2017-04-30 11:31 [PATCH 0/3] try to save some memory for kmem_cache in some cases Wei Yang
2017-04-30 11:31 ` [PATCH 1/3] mm/slub: pack red_left_pad with another int to save a word Wei Yang
2017-04-30 11:31 ` [PATCH 2/3] mm/slub: wrap cpu_slab->partial in CONFIG_SLUB_CPU_PARTIAL Wei Yang
@ 2017-04-30 11:31 ` Wei Yang
2017-05-01 15:37 ` Wei Yang
2017-04-30 21:22 ` [PATCH 0/3] try to save some memory for kmem_cache in some cases Christoph Lameter
3 siblings, 1 reply; 11+ messages in thread
From: Wei Yang @ 2017-04-30 11:31 UTC (permalink / raw)
To: cl, penberg, rientjes, iamjoonsoo.kim, akpm
Cc: linux-mm, linux-kernel, Wei Yang
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@gmail.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;
}
@@ -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
^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [PATCH 3/3] mm/slub: wrap kmem_cache->cpu_partial in config CONFIG_SLUB_CPU_PARTIAL
2017-04-30 11:31 ` [PATCH 3/3] mm/slub: wrap kmem_cache->cpu_partial in config CONFIG_SLUB_CPU_PARTIAL Wei Yang
@ 2017-05-01 15:37 ` Wei Yang
0 siblings, 0 replies; 11+ messages in thread
From: Wei Yang @ 2017-05-01 15:37 UTC (permalink / raw)
Cc: cl, penberg, rientjes, iamjoonsoo.kim, akpm, linux-mm,
linux-kernel, Wei Yang
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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@gmail.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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^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 0/3] try to save some memory for kmem_cache in some cases
2017-04-30 11:31 [PATCH 0/3] try to save some memory for kmem_cache in some cases Wei Yang
` (2 preceding siblings ...)
2017-04-30 11:31 ` [PATCH 3/3] mm/slub: wrap kmem_cache->cpu_partial in config CONFIG_SLUB_CPU_PARTIAL Wei Yang
@ 2017-04-30 21:22 ` Christoph Lameter
3 siblings, 0 replies; 11+ messages in thread
From: Christoph Lameter @ 2017-04-30 21:22 UTC (permalink / raw)
To: Wei Yang; +Cc: penberg, rientjes, iamjoonsoo.kim, akpm, linux-mm, linux-kernel
On Sun, 30 Apr 2017, Wei Yang wrote:
> kmem_cache is a frequently used data in kernel. During the code reading, I
> found maybe we could save some space in some cases.
>
> 1. On 64bit arch, type int will occupy a word if it doesn't sit well.
> 2. cpu_slab->partial is just used when CONFIG_SLUB_CPU_PARTIAL is set
> 3. cpu_partial is just used when CONFIG_SLUB_CPU_PARTIAL is set, while just
> save some space on 32bit arch.
This looks fine. But do we really want to add that amount of ifdeffery?
How much memory does this save?
^ permalink raw reply [flat|nested] 11+ messages in thread