Re: [PATCHv4 4/9] zsmalloc: make huge class watermark zs_pool member

Minchan Kim
2022-11-10T22:25:42Z

On Mon, Oct 31, 2022 at 02:41:03PM +0900, Sergey Senozhatsky wrote:
> We will permit per-pool configuration of pages per-zspage value,
> which changes characteristics of the classes and moves around
> huge class size watermark. Thus huge class size needs to be
> a per-pool variable.

I think part of code in previous patch should move here since
you are creating the feature in this patch:

BTW, I am wondering we really need to jump the per-pool config
option over global general golden ratio and/or smarter approach
to optimize transparently depending on how much memory we have
wasted.

>
> Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> ---
> mm/zsmalloc.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 5f79223e7bfe..d329bd673baa 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -178,7 +178,6 @@ static struct dentry *zs_stat_root;
> * (see: fix_fullness_group())
> */
> static const int fullness_threshold_frac = 4;
> -static size_t huge_class_size;
>
> struct size_class {
> spinlock_t lock;
> @@ -227,6 +226,7 @@ struct zs_pool {
>
> u32 num_size_classes;
> u32 min_alloc_size;
> + size_t huge_class_size;
>
> struct zs_pool_stats stats;
>
> @@ -1350,7 +1350,7 @@ EXPORT_SYMBOL_GPL(zs_unmap_object);
> */
> size_t zs_huge_class_size(struct zs_pool *pool)
> {
> - return huge_class_size;
> + return pool->huge_class_size;
> }
> EXPORT_SYMBOL_GPL(zs_huge_class_size);
>
> @@ -2262,8 +2262,8 @@ struct zs_pool *zs_create_pool(const char *name)
> * endup in the huge class.
> */
> if (pages_per_zspage != 1 && objs_per_zspage != 1 &&
> - !huge_class_size) {
> - huge_class_size = size;
> + !pool->huge_class_size) {
> + pool->huge_class_size = size;
> /*
> * The object uses ZS_HANDLE_SIZE bytes to store the
> * handle. We need to subtract it, because zs_malloc()
> @@ -2273,7 +2273,7 @@ struct zs_pool *zs_create_pool(const char *name)
> * class because it grows by ZS_HANDLE_SIZE extra bytes
> * right before class lookup.
> */
> - huge_class_size -= (ZS_HANDLE_SIZE - 1);
> + pool->huge_class_size -= (ZS_HANDLE_SIZE - 1);
> }
>
> /*
> --
> 2.38.1.273.g43a17bfeac-goog
>