On Fri, Dec 18, 2020 at 06:55:37PM +0100, Christian König wrote:
> Useful for testing.
>
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> ---
> drivers/gpu/drm/ttm/ttm_pool.c | 50 ++++++++++++++++++++++------------
> 1 file changed, 32 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c
> index 1d61e8fc0e81..1cdacd58753a 100644
> --- a/drivers/gpu/drm/ttm/ttm_pool.c
> +++ b/drivers/gpu/drm/ttm/ttm_pool.c
> @@ -529,6 +529,28 @@ void ttm_pool_fini(struct ttm_pool *pool)
> }
> EXPORT_SYMBOL(ttm_pool_fini);
>
> +/* As long as pages are available make sure to release at least one */
> +static unsigned long ttm_pool_shrinker_scan(struct shrinker *shrink,
> + struct shrink_control *sc)
> +{
> + unsigned long num_freed = 0;
> +
> + do
> + num_freed += ttm_pool_shrink();
> + while (!num_freed && atomic_long_read(&allocated_pages));
> +
> + return num_freed;
> +}
> +
> +/* Return the number of pages available or SHRINK_EMPTY if we have none */
> +static unsigned long ttm_pool_shrinker_count(struct shrinker *shrink,
> + struct shrink_control *sc)
> +{
> + unsigned long num_pages = atomic_long_read(&allocated_pages);
> +
> + return num_pages ? num_pages : SHRINK_EMPTY;
> +}
> +
> #ifdef CONFIG_DEBUG_FS
> /* Count the number of pages available in a pool_type */
> static unsigned int ttm_pool_type_count(struct ttm_pool_type *pt)
> @@ -633,29 +655,19 @@ int ttm_pool_debugfs(struct ttm_pool *pool, struct seq_file *m)
> }
> EXPORT_SYMBOL(ttm_pool_debugfs);
>
> -#endif
> -
> -/* As long as pages are available make sure to release at least one */
> -static unsigned long ttm_pool_shrinker_scan(struct shrinker *shrink,
> - struct shrink_control *sc)
> +/* Test the shrinker functions and dump the result */
> +static int ttm_pool_debugfs_shrink_show(struct seq_file *m, void *data)
> {
> - unsigned long num_freed = 0;
> + struct shrink_control sc = { .gfp_mask = GFP_KERNEL };
>
> - do
> - num_freed += ttm_pool_shrink();
> - while (!num_freed && atomic_long_read(&allocated_pages));
Need to wrap this in fs_reclaim_acquire/release(), otherwise lockdep won't
connect the dots and the dedicated testing interface here isn't very
useful.
Also this is a bit a confusing interface, I'd expect the show function to
do the counting, and then the write function would try to write shrink as
many objects as requests with the _scan function.
Both should be annotated with fs_reclaim_acquire/release.
> + seq_printf(m, "%lu/%lu\n", ttm_pool_shrinker_count(&mm_shrinker, &sc),
> + ttm_pool_shrinker_scan(&mm_shrinker, &sc));
>
> - return num_freed;
> + return 0;
> }
> +DEFINE_SHOW_ATTRIBUTE(ttm_pool_debugfs_shrink);
>
> -/* Return the number of pages available or SHRINK_EMPTY if we have none */
> -static unsigned long ttm_pool_shrinker_count(struct shrinker *shrink,
> - struct shrink_control *sc)
> -{
> - unsigned long num_pages = atomic_long_read(&allocated_pages);
> -
> - return num_pages ? num_pages : SHRINK_EMPTY;
> -}
> +#endif
>
> /**
> * ttm_pool_mgr_init - Initialize globals
> @@ -688,6 +700,8 @@ int ttm_pool_mgr_init(unsigned long num_pages)
> #ifdef CONFIG_DEBUG_FS
> debugfs_create_file("page_pool", 0444, ttm_debugfs_root, NULL,
> &ttm_pool_debugfs_globals_fops);
> + debugfs_create_file("page_pool_shrink", 0400, ttm_debugfs_root, NULL,
> + &ttm_pool_debugfs_shrink_fops);
I think an interface per pool would make more sense for dedicated testing.
I'm kinda wondering whether we shouldn't do this in mm/ for all shrinkers
by default, it's really quite neat for being able to test stuff.
-Daniel
> #endif
>
> mm_shrinker.count_objects = ttm_pool_shrinker_count;
> --
> 2.25.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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