On 07/03/2012 06:15 AM, Seth Jennings wrote:
> Improve zs_unmap_object() performance by adding a fast path for
> objects that don't span pages.
>
> Signed-off-by: Seth Jennings <sjenn...@linux.vnet.ibm.com>
> ---
> drivers/staging/zsmalloc/zsmalloc-main.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c
> b/drivers/staging/zsmalloc/zsmalloc-main.c
> index a7a6f22..4942d41 100644
> --- a/drivers/staging/zsmalloc/zsmalloc-main.c
> +++ b/drivers/staging/zsmalloc/zsmalloc-main.c
> @@ -774,6 +774,7 @@ void *zs_map_object(struct zs_pool *pool, unsigned long
> handle)
> }
>
> zs_copy_map_object(area->vm_buf, page, off, class->size);
> + area->vm_addr = NULL;
> return area->vm_buf;
> }
> EXPORT_SYMBOL_GPL(zs_map_object);
> @@ -788,6 +789,14 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long
> handle)
> struct size_class *class;
> struct mapping_area *area;
>
> + area = &__get_cpu_var(zs_map_area);
> + if (area->vm_addr) {
> + /* single-page object fastpath */
> + kunmap_atomic(area->vm_addr);
> + put_cpu_var(zs_map_area);
> + return;
> + }
> +
Please locate this after below BUG_ON.
The BUG check is still effective regardless of your fast path patch.
> BUG_ON(!handle);
>
> obj_handle_to_location(handle, &page, &obj_idx);
> @@ -795,11 +804,7 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long
> handle)
> class = &pool->size_class[class_idx];
> off = obj_idx_to_offset(page, obj_idx, class->size);
>
> - area = &__get_cpu_var(zs_map_area);
> - if (off + class->size <= PAGE_SIZE)
> - kunmap_atomic(area->vm_addr);
> - else
> - zs_copy_unmap_object(area->vm_buf, page, off, class->size);
> + zs_copy_unmap_object(area->vm_buf, page, off, class->size);
> put_cpu_var(zs_map_area);
> }
> EXPORT_SYMBOL_GPL(zs_unmap_object);
>
--
Kind regards,
Minchan Kim
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