[PATCH v2] Remove node's validity check in alloc_pages

[PATCH v2] Remove node's validity check in alloc_pages

[Minchan Kim]

V2
 * Add some reviewed-by

alloc_pages calls alloc_pages_node with numa_node_id().
alloc_pages_node can't see nid < 0.

So we can use alloc_pages_exact_node instead of alloc_pages_node.
It could avoid comparison and branch as 6484eb3e2a81807722 tried.

Reviewed-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujisu.com>
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
---
 include/linux/gfp.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 4c6d413..b65f003 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -308,7 +308,7 @@ extern struct page *alloc_page_vma(gfp_t gfp_mask,
 			struct vm_area_struct *vma, unsigned long addr);
 #else
 #define alloc_pages(gfp_mask, order) \
-		alloc_pages_node(numa_node_id(), gfp_mask, order)
+		alloc_pages_exact_node(numa_node_id(), gfp_mask, order)
 #define alloc_page_vma(gfp_mask, vma, addr) alloc_pages(gfp_mask, 0)
 #endif
 #define alloc_page(gfp_mask) alloc_pages(gfp_mask, 0)
-- 
1.7.0.5

[PATCH v2] Remove node's validity check in alloc_pages

[Minchan Kim]

V2
 * Add some reviewed-by

alloc_pages calls alloc_pages_node with numa_node_id().
alloc_pages_node can't see nid < 0.

So we can use alloc_pages_exact_node instead of alloc_pages_node.
It could avoid comparison and branch as 6484eb3e2a81807722 tried.

Reviewed-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujisu.com>
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
---
 include/linux/gfp.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 4c6d413..b65f003 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -308,7 +308,7 @@ extern struct page *alloc_page_vma(gfp_t gfp_mask,
 			struct vm_area_struct *vma, unsigned long addr);
 #else
 #define alloc_pages(gfp_mask, order) \
-		alloc_pages_node(numa_node_id(), gfp_mask, order)
+		alloc_pages_exact_node(numa_node_id(), gfp_mask, order)
 #define alloc_page_vma(gfp_mask, vma, addr) alloc_pages(gfp_mask, 0)
 #endif
 #define alloc_page(gfp_mask) alloc_pages(gfp_mask, 0)
-- 
1.7.0.5

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[PATCH] change alloc function in pcpu_alloc_pages

[Minchan Kim]

alloc_pages_node is called with cpu_to_node(cpu).
I think cpu_to_node(cpu) never returns -1.
(But I am not sure we need double check.)

So we can use alloc_pages_exact_node instead of alloc_pages_node.
It could avoid comparison and branch as 6484eb3e2a81807722 tried.

Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
---
 mm/percpu.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/percpu.c b/mm/percpu.c
index 768419d..ec3e671 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -720,7 +720,7 @@ static int pcpu_alloc_pages(struct pcpu_chunk *chunk,
 		for (i = page_start; i < page_end; i++) {
 			struct page **pagep = &pages[pcpu_page_idx(cpu, i)];
 
-			*pagep = alloc_pages_node(cpu_to_node(cpu), gfp, 0);
+			*pagep = alloc_pages_exact_node(cpu_to_node(cpu), gfp, 0);
 			if (!*pagep) {
 				pcpu_free_pages(chunk, pages, populated,
 						page_start, page_end);
-- 
1.7.0.5

[PATCH] change alloc function in pcpu_alloc_pages

[Minchan Kim]

alloc_pages_node is called with cpu_to_node(cpu).
I think cpu_to_node(cpu) never returns -1.
(But I am not sure we need double check.)

So we can use alloc_pages_exact_node instead of alloc_pages_node.
It could avoid comparison and branch as 6484eb3e2a81807722 tried.

Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
---
 mm/percpu.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/percpu.c b/mm/percpu.c
index 768419d..ec3e671 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -720,7 +720,7 @@ static int pcpu_alloc_pages(struct pcpu_chunk *chunk,
 		for (i = page_start; i < page_end; i++) {
 			struct page **pagep = &pages[pcpu_page_idx(cpu, i)];
 
-			*pagep = alloc_pages_node(cpu_to_node(cpu), gfp, 0);
+			*pagep = alloc_pages_exact_node(cpu_to_node(cpu), gfp, 0);
 			if (!*pagep) {
 				pcpu_free_pages(chunk, pages, populated,
 						page_start, page_end);
-- 
1.7.0.5

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[PATCH v2] change alloc function in alloc_slab_page

[Minchan Kim]

V2
* change changelog
* Add some reviewed-by 

alloc_slab_page always checks nid == -1, so alloc_page_node can't be
called with -1. 
It means node's validity check in alloc_pages_node is unnecessary. 
So we can use alloc_pages_exact_node instead of alloc_pages_node. 
It could avoid comparison and branch as 6484eb3e2a81807722 tried.

Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Mel Gorman <mel@csn.ul.ie>
---
 mm/slub.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index b364844..9984165 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1084,7 +1084,7 @@ static inline struct page *alloc_slab_page(gfp_t flags, int node,
 	if (node == -1)
 		return alloc_pages(flags, order);
 	else
-		return alloc_pages_node(node, flags, order);
+		return alloc_pages_exact_node(node, flags, order);
 }
 
 static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
-- 
1.7.0.5

[PATCH v2] change alloc function in alloc_slab_page

[Minchan Kim]

V2
* change changelog
* Add some reviewed-by 

alloc_slab_page always checks nid == -1, so alloc_page_node can't be
called with -1. 
It means node's validity check in alloc_pages_node is unnecessary. 
So we can use alloc_pages_exact_node instead of alloc_pages_node. 
It could avoid comparison and branch as 6484eb3e2a81807722 tried.

Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Mel Gorman <mel@csn.ul.ie>
---
 mm/slub.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index b364844..9984165 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1084,7 +1084,7 @@ static inline struct page *alloc_slab_page(gfp_t flags, int node,
 	if (node == -1)
 		return alloc_pages(flags, order);
 	else
-		return alloc_pages_node(node, flags, order);
+		return alloc_pages_exact_node(node, flags, order);
 }
 
 static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
-- 
1.7.0.5

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[PATCH v2] change alloc function in vmemmap_alloc_block

[Minchan Kim]

V2
* Add some reviewed-by

if node_state is N_HIGH_MEMORY, node doesn't have -1.
It means node's validity check is unnecessary.
So we can use alloc_pages_exact_node instead of alloc_pages_node.
It could avoid comparison and branch as 6484eb3e2a81807722 tried.

Cc: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
---
 mm/sparse-vmemmap.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index 392b9bb..7710ebc 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -53,7 +53,7 @@ void * __meminit vmemmap_alloc_block(unsigned long size, int node)
 		struct page *page;
 
 		if (node_state(node, N_HIGH_MEMORY))
-			page = alloc_pages_node(node,
+			page = alloc_pages_exact_node(node,
 				GFP_KERNEL | __GFP_ZERO, get_order(size));
 		else
 			page = alloc_pages(GFP_KERNEL | __GFP_ZERO,
-- 
1.7.0.5

[PATCH v2] change alloc function in vmemmap_alloc_block

[Minchan Kim]

V2
* Add some reviewed-by

if node_state is N_HIGH_MEMORY, node doesn't have -1.
It means node's validity check is unnecessary.
So we can use alloc_pages_exact_node instead of alloc_pages_node.
It could avoid comparison and branch as 6484eb3e2a81807722 tried.

Cc: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
---
 mm/sparse-vmemmap.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index 392b9bb..7710ebc 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -53,7 +53,7 @@ void * __meminit vmemmap_alloc_block(unsigned long size, int node)
 		struct page *page;
 
 		if (node_state(node, N_HIGH_MEMORY))
-			page = alloc_pages_node(node,
+			page = alloc_pages_exact_node(node,
 				GFP_KERNEL | __GFP_ZERO, get_order(size));
 		else
 			page = alloc_pages(GFP_KERNEL | __GFP_ZERO,
-- 
1.7.0.5

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[PATCH v2] change alloc function in __vmalloc_area_node

[Minchan Kim]

V2
* Add some reviewed-by

__vmalloc_area_node never pass -1 to alloc_pages_node.
It means node's validity check is unnecessary.
So we can use alloc_pages_exact_node instead of alloc_pages_node.
It could avoid comparison and branch as 6484eb3e2a81807722 tried.

Cc: Nick Piggin <npiggin@suse.de>
Reviewed-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
---
 mm/vmalloc.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index ae00746..7abf423 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1499,7 +1499,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
 		if (node < 0)
 			page = alloc_page(gfp_mask);
 		else
-			page = alloc_pages_node(node, gfp_mask, 0);
+			page = alloc_pages_exact_node(node, gfp_mask, 0);
 
 		if (unlikely(!page)) {
 			/* Successfully allocated i pages, free them in __vunmap() */
-- 
1.7.0.5

[PATCH v2] change alloc function in __vmalloc_area_node

[Minchan Kim]

V2
* Add some reviewed-by

__vmalloc_area_node never pass -1 to alloc_pages_node.
It means node's validity check is unnecessary.
So we can use alloc_pages_exact_node instead of alloc_pages_node.
It could avoid comparison and branch as 6484eb3e2a81807722 tried.

Cc: Nick Piggin <npiggin@suse.de>
Reviewed-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
---
 mm/vmalloc.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index ae00746..7abf423 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1499,7 +1499,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
 		if (node < 0)
 			page = alloc_page(gfp_mask);
 		else
-			page = alloc_pages_node(node, gfp_mask, 0);
+			page = alloc_pages_exact_node(node, gfp_mask, 0);
 
 		if (unlikely(!page)) {
 			/* Successfully allocated i pages, free them in __vunmap() */
-- 
1.7.0.5

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[PATCH v2] Add comment in alloc_pages_exact_node

[Minchan Kim]

V2
 o modify comment by suggestion. (Thanks to Mel)

alloc_pages_exact_node naming makes some people misleading.
They considered it following as.
"This function will allocate pages from node which I wanted
exactly".
But it can allocate pages from fallback list if page allocator
can't find free page from node user wanted.

So let's comment this NOTE.

Actually I wanted to change naming with better.
ex) alloc_pages_explict_node.
But I changed my mind since the comment would be enough.

If anybody suggests better name, I will do with pleasure.

Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Bob Liu <lliubbo@gmail.com>
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
---
 include/linux/gfp.h |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index b65f003..56b5fe6 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -288,6 +288,12 @@ static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask,
 	return __alloc_pages(gfp_mask, order, node_zonelist(nid, gfp_mask));
 }
 
+/*
+ * Use this instead of alloc_pages_node when the caller knows
+ * exactly which node they need (as opposed to passing in -1
+ * for current). Fallback to other nodes will still occur
+ * unless __GFP_THISNODE is specified.
+ */
 static inline struct page *alloc_pages_exact_node(int nid, gfp_t gfp_mask,
 						unsigned int order)
 {
-- 
1.7.0.5

[PATCH v2] Add comment in alloc_pages_exact_node

[Minchan Kim]

V2
 o modify comment by suggestion. (Thanks to Mel)

alloc_pages_exact_node naming makes some people misleading.
They considered it following as.
"This function will allocate pages from node which I wanted
exactly".
But it can allocate pages from fallback list if page allocator
can't find free page from node user wanted.

So let's comment this NOTE.

Actually I wanted to change naming with better.
ex) alloc_pages_explict_node.
But I changed my mind since the comment would be enough.

If anybody suggests better name, I will do with pleasure.

Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Bob Liu <lliubbo@gmail.com>
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
---
 include/linux/gfp.h |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index b65f003..56b5fe6 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -288,6 +288,12 @@ static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask,
 	return __alloc_pages(gfp_mask, order, node_zonelist(nid, gfp_mask));
 }
 
+/*
+ * Use this instead of alloc_pages_node when the caller knows
+ * exactly which node they need (as opposed to passing in -1
+ * for current). Fallback to other nodes will still occur
+ * unless __GFP_THISNODE is specified.
+ */
 static inline struct page *alloc_pages_exact_node(int nid, gfp_t gfp_mask,
 						unsigned int order)
 {
-- 
1.7.0.5

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Re: [PATCH v2] change alloc function in alloc_slab_page

[Pekka Enberg]

Minchan Kim wrote:
> V2
> * change changelog
> * Add some reviewed-by 
> 
> alloc_slab_page always checks nid == -1, so alloc_page_node can't be
> called with -1. 
> It means node's validity check in alloc_pages_node is unnecessary. 
> So we can use alloc_pages_exact_node instead of alloc_pages_node. 
> It could avoid comparison and branch as 6484eb3e2a81807722 tried.
> 
> Cc: Pekka Enberg <penberg@cs.helsinki.fi>
> Cc: Christoph Lameter <cl@linux-foundation.org>
> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Reviewed-by: Mel Gorman <mel@csn.ul.ie>
> ---
>  mm/slub.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index b364844..9984165 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1084,7 +1084,7 @@ static inline struct page *alloc_slab_page(gfp_t flags, int node,
>  	if (node == -1)
>  		return alloc_pages(flags, order);
>  	else
> -		return alloc_pages_node(node, flags, order);
> +		return alloc_pages_exact_node(node, flags, order);
>  }
>  
>  static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)

Applied, thanks!

Re: [PATCH v2] change alloc function in alloc_slab_page

[Pekka Enberg]

Minchan Kim wrote:
> V2
> * change changelog
> * Add some reviewed-by 
> 
> alloc_slab_page always checks nid == -1, so alloc_page_node can't be
> called with -1. 
> It means node's validity check in alloc_pages_node is unnecessary. 
> So we can use alloc_pages_exact_node instead of alloc_pages_node. 
> It could avoid comparison and branch as 6484eb3e2a81807722 tried.
> 
> Cc: Pekka Enberg <penberg@cs.helsinki.fi>
> Cc: Christoph Lameter <cl@linux-foundation.org>
> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Reviewed-by: Mel Gorman <mel@csn.ul.ie>
> ---
>  mm/slub.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index b364844..9984165 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1084,7 +1084,7 @@ static inline struct page *alloc_slab_page(gfp_t flags, int node,
>  	if (node == -1)
>  		return alloc_pages(flags, order);
>  	else
> -		return alloc_pages_node(node, flags, order);
> +		return alloc_pages_exact_node(node, flags, order);
>  }
>  
>  static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)

Applied, thanks!

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