Re: [PATCH 1/2] mm: add context argument to shrinker callback

[Avi Kivity <avi@redhat.com>]

On 04/13/2010 03:24 AM, Dave Chinner wrote:
> From: Dave Chinner<dchinner@redhat.com>
>
> The current shrinker implementation requires the registered callback
> to have global state to work from. This makes it difficult to shrink
> caches that are not global (e.g. per-filesystem caches). Add a
> context argument to the shrinker callback so that it can easily be
> used in such situations.
>    

> @@ -995,7 +995,8 @@ static inline void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
>    * querying the cache size, so a fastpath for that case is appropriate.
>    */
>   struct shrinker {
> -	int (*shrink)(int nr_to_scan, gfp_t gfp_mask);
> +	int (*shrink)(void *ctx, int nr_to_scan, gfp_t gfp_mask);
> +	void *ctx;	/* user callback context */
>   	int seeks;	/* seeks to recreate an obj */
>    


It's nicer (and slightly cheaper) to have

   int (*shrink)(struct shrinker *shrinker, int nr_to_scan, gfp_t gfp_mask);
   /* no void *ctx; */

Clients can use container_of() to reach their context from the shrinker 
argument.

-- 
error compiling committee.c: too many arguments to function

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