[PATCH chao/erofs-dev 1/2] staging: erofs: separate into init_once / always

[Chao Yu]

On 2018/10/19 14:41, Gao Xiang wrote:
> `z_erofs_vle_workgroup' is heavily generated in the decompression,
> for example, it resets 32 bytes redundantly for 64-bit platforms
> even through Z_EROFS_VLE_INLINE_PAGEVECS + Z_EROFS_CLUSTER_MAX_PAGES,
> default 4, pages are stored in `z_erofs_vle_workgroup'.
> 
> As an another example, `struct mutex' takes 72 bytes for our kirin
> 64-bit platforms, it's unnecessary to be reseted at first and
> be initialized each time.
> 
> Let's avoid filling all `z_erofs_vle_workgroup' with 0 at first
> since most fields are reinitialized to meaningful values later,
> and pagevec is no need to initialized at all.
> 
> Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
> ---
>  drivers/staging/erofs/unzip_vle.c | 34 +++++++++++++++++++++++++++++-----
>  1 file changed, 29 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c
> index 79d3ba62b298..7aa26818054a 100644
> --- a/drivers/staging/erofs/unzip_vle.c
> +++ b/drivers/staging/erofs/unzip_vle.c
> @@ -42,12 +42,38 @@ static inline int init_unzip_workqueue(void)
>  	return z_erofs_workqueue != NULL ? 0 : -ENOMEM;
>  }
>  
> +static void init_once(void *ptr)

How about rename it to init_vle_workgroup() for better readability?

> +{
> +	struct z_erofs_vle_workgroup *grp = ptr;
> +	struct z_erofs_vle_work *const work =
> +		z_erofs_vle_grab_primary_work(grp);
> +	unsigned int i;
> +
> +	mutex_init(&work->lock);
> +	work->nr_pages = 0;
> +	work->vcnt = 0;
> +	for (i = 0; i < Z_EROFS_CLUSTER_MAX_PAGES; ++i)
> +		grp->compressed_pages[i] = NULL;
> +}
> +
> +static void init_always(struct z_erofs_vle_workgroup *grp)

Ditto, maybe reset_vle_workgroup().

Otherwise, it looks good to me.

Reviewed-by: Chao Yu <yuchao0 at huawei.com>

Thanks,

> +{
> +	struct z_erofs_vle_work *const work =
> +		z_erofs_vle_grab_primary_work(grp);
> +
> +	atomic_set(&grp->obj.refcount, 1);
> +	grp->flags = 0;
> +
> +	DBG_BUGON(work->nr_pages);
> +	DBG_BUGON(work->vcnt);
> +}
> +
>  int __init z_erofs_init_zip_subsystem(void)
>  {
>  	z_erofs_workgroup_cachep =
>  		kmem_cache_create("erofs_compress",
>  		Z_EROFS_WORKGROUP_SIZE, 0,
> -		SLAB_RECLAIM_ACCOUNT, NULL);
> +		SLAB_RECLAIM_ACCOUNT, init_once);
>  
>  	if (z_erofs_workgroup_cachep != NULL) {
>  		if (!init_unzip_workqueue())
> @@ -369,10 +395,11 @@ z_erofs_vle_work_register(const struct z_erofs_vle_work_finder *f,
>  	BUG_ON(grp != NULL);
>  
>  	/* no available workgroup, let's allocate one */
> -	grp = kmem_cache_zalloc(z_erofs_workgroup_cachep, GFP_NOFS);
> +	grp = kmem_cache_alloc(z_erofs_workgroup_cachep, GFP_NOFS);
>  	if (unlikely(grp == NULL))
>  		return ERR_PTR(-ENOMEM);
>  
> +	init_always(grp);
>  	grp->obj.index = f->idx;
>  	grp->llen = map->m_llen;
>  
> @@ -380,7 +407,6 @@ z_erofs_vle_work_register(const struct z_erofs_vle_work_finder *f,
>  		(map->m_flags & EROFS_MAP_ZIPPED) ?
>  			Z_EROFS_VLE_WORKGRP_FMT_LZ4 :
>  			Z_EROFS_VLE_WORKGRP_FMT_PLAIN);
> -	atomic_set(&grp->obj.refcount, 1);
>  
>  	/* new workgrps have been claimed as type 1 */
>  	WRITE_ONCE(grp->next, *f->owned_head);
> @@ -393,8 +419,6 @@ z_erofs_vle_work_register(const struct z_erofs_vle_work_finder *f,
>  	work = z_erofs_vle_grab_primary_work(grp);
>  	work->pageofs = f->pageofs;
>  
> -	mutex_init(&work->lock);
> -
>  	if (gnew) {
>  		int err = erofs_register_workgroup(f->sb, &grp->obj, 0);
>  
>