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[PATCH] mm/vmalloc: terminate searching since one node found

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  [PATCH] mm/vmalloc: terminate searching since one node found Zhaoyang Huang <huangzhaoyang@gmail.com> - 2017-07-16 09:30 +0200
    Re: [PATCH] mm/vmalloc: terminate searching since one node found Michal Hocko <mhocko@kernel.org> - 2017-07-17 09:10 +0200

#1688146 — [PATCH] mm/vmalloc: terminate searching since one node found

It is no need to find the very beginning of the area within
alloc_vmap_area, which can be done by judging each node during the process

Signed-off-by: Zhaoyang Huang <zhaoyang.huang@spreadtrum.com>
Signed-off-by: Zhaoyang Huang <huangzhaoyang@gmail.com>
---
 mm/vmalloc.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 34a1c3e..f833e07 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -459,9 +459,16 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
 
 		while (n) {
 			struct vmap_area *tmp;
+			struct vmap_area *tmp_next;
 			tmp = rb_entry(n, struct vmap_area, rb_node);
+			tmp_next = list_next_entry(tmp, list);
 			if (tmp->va_end >= addr) {
 				first = tmp;
+				if (ALIGN(tmp->va_end, align) + size
+						< tmp_next->va_start) {
+					addr = ALIGN(tmp->va_end, align);
+					goto found;
+				}
 				if (tmp->va_start <= addr)
 					break;
 				n = n->rb_left;
-- 
1.9.1

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#1688709

On Sun 16-07-17 15:28:27, Zhaoyang Huang wrote:
> It is no need to find the very beginning of the area within
> alloc_vmap_area, which can be done by judging each node during the process

Please describe _why_ the patch is needed. I suspect this is an
optimization but for which workloads it matters and how much.

> Signed-off-by: Zhaoyang Huang <zhaoyang.huang@spreadtrum.com>
> Signed-off-by: Zhaoyang Huang <huangzhaoyang@gmail.com>

no need to to make your s-o-b twice. Just use the same one as the From
(author of the patch).

> ---
>  mm/vmalloc.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 34a1c3e..f833e07 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -459,9 +459,16 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
>  
>  		while (n) {
>  			struct vmap_area *tmp;
> +			struct vmap_area *tmp_next;
>  			tmp = rb_entry(n, struct vmap_area, rb_node);
> +			tmp_next = list_next_entry(tmp, list);
>  			if (tmp->va_end >= addr) {
>  				first = tmp;
> +				if (ALIGN(tmp->va_end, align) + size
> +						< tmp_next->va_start) {
> +					addr = ALIGN(tmp->va_end, align);
> +					goto found;
> +				}
>  				if (tmp->va_start <= addr)
>  					break;
>  				n = n->rb_left;
> -- 
> 1.9.1
> 

-- 
Michal Hocko
SUSE Labs

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