On Thu, Nov 20, 2014 at 8:08 AM, Mahendran Ganesh
<opensource.ganesh@xxxxxxxxx> wrote:
> In zs_create_pool(), prev_class is assigned (ZS_SIZE_CLASSES - 1)
> times. And the prev_class only references to the previous alloc
> size_class. So we do not need unnecessary assignement.
>
> This patch modifies *prev_class* to *prev_alloc_class*. And the
> *prev_alloc_class* will only be assigned when a new size_class
> structure is allocated.
>
> Signed-off-by: Mahendran Ganesh <opensource.ganesh@xxxxxxxxx>
> ---
> mm/zsmalloc.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index b3b57ef..ac2b396 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -970,7 +970,7 @@ struct zs_pool *zs_create_pool(gfp_t flags)
> int size;
> int pages_per_zspage;
> struct size_class *class;
> - struct size_class *prev_class;
> + struct size_class *uninitialized_var(prev_alloc_class);
+ struct size_class *prev_class = NULL;
Use the fact it's unset below, so set it to NULL here
>
> size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA;
> if (size > ZS_MAX_ALLOC_SIZE)
> @@ -987,9 +987,8 @@ struct zs_pool *zs_create_pool(gfp_t flags)
> * previous size_class if possible.
> */
> if (i < ZS_SIZE_CLASSES - 1) {
> - prev_class = pool->size_class[i + 1];
> - if (can_merge(prev_class, size, pages_per_zspage)) {
> - pool->size_class[i] = prev_class;
> + if (can_merge(prev_alloc_class, size, pages_per_zspage)) {
> + pool->size_class[i] = prev_alloc_class;
simplify more, we can check if this is the first iteration by looking
at prev_class, e.g.:
if (prev_class) {
if (can_merge(prev_class, size, pages_per_zspage)) {
pool->size_class[i] = prev_class;
> continue;
> }
> }
> @@ -1003,6 +1002,8 @@ struct zs_pool *zs_create_pool(gfp_t flags)
> class->pages_per_zspage = pages_per_zspage;
> spin_lock_init(&class->lock);
> pool->size_class[i] = class;
> +
> + prev_alloc_class = class;
> }
>
> pool->flags = flags;
> --
> 1.7.9.5
>
> --
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