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Date: Thu, 7 Feb 2013 11:27:54 +0900
From: Chanho Min <chanho.min@....com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Cong Wang <amwang@...hat.com>,
Nicolas Pitre <nicolas.pitre@...aro.org>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH] vmalloc: Remove alloc_map from vmap_block.
There is no reason to maintain alloc_map in the vmap_block.
The use of alloc_map may require heavy bitmap operation sometimes.
In the worst-case, We need 1024 for-loops to find 1 free bit and
thus cause overhead. vmap_block is fragmented unnecessarily by
2 order alignment as well.
Instead we can map by using vb->free in order. When It is freed,
Its corresponding bit will be set in the dirty_map and all
free/purge operations are carried out in the dirty_map.
vmap_block is not fragmented sporadically anymore and thus
purge_fragmented_blocks_thiscpu in the vb_alloc can be removed.
Signed-off-by: Chanho Min <chanho.min@....com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
---
mm/vmalloc.c | 23 +----------------------
1 file changed, 1 insertion(+), 22 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 5123a16..4fd3555 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -744,7 +744,6 @@ struct vmap_block {
struct vmap_area *va;
struct vmap_block_queue *vbq;
unsigned long free, dirty;
- DECLARE_BITMAP(alloc_map, VMAP_BBMAP_BITS);
DECLARE_BITMAP(dirty_map, VMAP_BBMAP_BITS);
struct list_head free_list;
struct rcu_head rcu_head;
@@ -810,7 +809,6 @@ static struct vmap_block *new_vmap_block(gfp_t gfp_mask)
vb->va = va;
vb->free = VMAP_BBMAP_BITS;
vb->dirty = 0;
- bitmap_zero(vb->alloc_map, VMAP_BBMAP_BITS);
bitmap_zero(vb->dirty_map, VMAP_BBMAP_BITS);
INIT_LIST_HEAD(&vb->free_list);
@@ -863,7 +861,6 @@ static void purge_fragmented_blocks(int cpu)
if (vb->free + vb->dirty == VMAP_BBMAP_BITS && vb->dirty !=
VMAP_BBMAP_BITS) {
vb->free = 0; /* prevent further allocs after releasing lock */
vb->dirty = VMAP_BBMAP_BITS; /* prevent purging it again */
- bitmap_fill(vb->alloc_map, VMAP_BBMAP_BITS);
bitmap_fill(vb->dirty_map, VMAP_BBMAP_BITS);
spin_lock(&vbq->lock);
list_del_rcu(&vb->free_list);
@@ -881,11 +878,6 @@ static void purge_fragmented_blocks(int cpu)
}
}
-static void purge_fragmented_blocks_thiscpu(void)
-{
- purge_fragmented_blocks(smp_processor_id());
-}
-
static void purge_fragmented_blocks_allcpus(void)
{
int cpu;
@@ -900,7 +892,6 @@ static void *vb_alloc(unsigned long size, gfp_t gfp_mask)
struct vmap_block *vb;
unsigned long addr = 0;
unsigned int order;
- int purge = 0;
BUG_ON(size & ~PAGE_MASK);
BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);
@@ -924,17 +915,8 @@ again:
if (vb->free < 1UL << order)
goto next;
- i = bitmap_find_free_region(vb->alloc_map,
- VMAP_BBMAP_BITS, order);
+ i = VMAP_BBMAP_BITS - vb->free;
- if (i < 0) {
- if (vb->free + vb->dirty == VMAP_BBMAP_BITS) {
- /* fragmented and no outstanding allocations */
- BUG_ON(vb->dirty != VMAP_BBMAP_BITS);
- purge = 1;
- }
- goto next;
- }
addr = vb->va->va_start + (i << PAGE_SHIFT);
BUG_ON(addr_to_vb_idx(addr) !=
addr_to_vb_idx(vb->va->va_start));
@@ -950,9 +932,6 @@ next:
spin_unlock(&vb->lock);
}
- if (purge)
- purge_fragmented_blocks_thiscpu();
-
put_cpu_var(vmap_block_queue);
rcu_read_unlock();
--
1.7.9.5
--
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