[PATCH 3/7] zram: Speed insertion of new pages with cached idx

Robert Jennings
2011-01-26T17:24:00Z

Calculate the first- and second-level indices for new page when the pool
is initialized rather than calculating them on each insertion.

Signed-off-by: Robert Jennings <rcj@linux.vnet.ibm.com>
---
drivers/staging/zram/xvmalloc.c | 13 +++++++++++--
drivers/staging/zram/xvmalloc_int.h | 4 ++++
2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/zram/xvmalloc.c b/drivers/staging/zram/xvmalloc.c
index 3fdbb8a..a507f95 100644
--- a/drivers/staging/zram/xvmalloc.c
+++ b/drivers/staging/zram/xvmalloc.c
@@ -184,8 +184,13 @@ static void insert_block(struct xv_pool *pool, struct page *page, u32 offset,
u32 flindex, slindex;
struct block_header *nextblock;

- slindex = get_index_for_insert(block->size);
- flindex = slindex / BITS_PER_LONG;
+ if (block->size >= (PAGE_SIZE - XV_ALIGN)) {
+ slindex = pagesize_slindex;
+ flindex = pagesize_flindex;
+ } else {
+ slindex = get_index_for_insert(block->size);
+ flindex = slindex / BITS_PER_LONG;
+ }

block->link.prev_page = 0;
block->link.prev_offset = 0;
@@ -316,6 +321,10 @@ struct xv_pool *xv_create_pool(void)
if (!pool)
return NULL;

+ /* cache the first/second-level indices for PAGE_SIZE allocations */
+ pagesize_slindex = get_index_for_insert(PAGE_SIZE);
+ pagesize_flindex = pagesize_slindex / BITS_PER_LONG;
+
spin_lock_init(&pool->lock);

return pool;
diff --git a/drivers/staging/zram/xvmalloc_int.h b/drivers/staging/zram/xvmalloc_int.h
index 051a49b..68db384 100644
--- a/drivers/staging/zram/xvmalloc_int.h
+++ b/drivers/staging/zram/xvmalloc_int.h
@@ -52,6 +52,10 @@

/* End of user params */

+/* Cache of the first/second-level indices for PAGE_SIZE allocations */
+static u32 pagesize_slindex;
+static u32 pagesize_flindex;
+
enum blockflags {
BLOCK_FREE,
PREV_FREE,
--
1.6.0.2