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author | Rusty Russell <rusty@rustcorp.com.au> | 2007-07-17 13:03:17 +0200 |
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committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-07-17 19:23:00 +0200 |
commit | 8e1f936b73150f5095448a0fee6d4f30a1f9001d (patch) | |
tree | 0996203e35c629e2ec243d128c7bd91ecd74d24a /include | |
parent | Lumpy Reclaim V4 (diff) | |
download | linux-8e1f936b73150f5095448a0fee6d4f30a1f9001d.tar.xz linux-8e1f936b73150f5095448a0fee6d4f30a1f9001d.zip |
mm: clean up and kernelify shrinker registration
I can never remember what the function to register to receive VM pressure
is called. I have to trace down from __alloc_pages() to find it.
It's called "set_shrinker()", and it needs Your Help.
1) Don't hide struct shrinker. It contains no magic.
2) Don't allocate "struct shrinker". It's not helpful.
3) Call them "register_shrinker" and "unregister_shrinker".
4) Call the function "shrink" not "shrinker".
5) Reduce the 17 lines of waffly comments to 13, but document it properly.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: David Chinner <dgc@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/mm.h | 38 |
1 files changed, 21 insertions, 17 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 97d0cddfd223..4c482a3ee870 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -810,27 +810,31 @@ extern unsigned long do_mremap(unsigned long addr, unsigned long flags, unsigned long new_addr); /* - * Prototype to add a shrinker callback for ageable caches. - * - * These functions are passed a count `nr_to_scan' and a gfpmask. They should - * scan `nr_to_scan' objects, attempting to free them. + * A callback you can register to apply pressure to ageable caches. * - * The callback must return the number of objects which remain in the cache. + * 'shrink' is passed a count 'nr_to_scan' and a 'gfpmask'. It should + * look through the least-recently-used 'nr_to_scan' entries and + * attempt to free them up. It should return the number of objects + * which remain in the cache. If it returns -1, it means it cannot do + * any scanning at this time (eg. there is a risk of deadlock). * - * The callback will be passed nr_to_scan == 0 when the VM is querying the - * cache size, so a fastpath for that case is appropriate. - */ -typedef int (*shrinker_t)(int nr_to_scan, gfp_t gfp_mask); - -/* - * Add an aging callback. The int is the number of 'seeks' it takes - * to recreate one of the objects that these functions age. + * The 'gfpmask' refers to the allocation we are currently trying to + * fulfil. + * + * Note that 'shrink' will be passed nr_to_scan == 0 when the VM is + * 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 seeks; /* seeks to recreate an obj */ -#define DEFAULT_SEEKS 2 -struct shrinker; -extern struct shrinker *set_shrinker(int, shrinker_t); -extern void remove_shrinker(struct shrinker *shrinker); + /* These are for internal use */ + struct list_head list; + long nr; /* objs pending delete */ +}; +#define DEFAULT_SEEKS 2 /* A good number if you don't know better. */ +extern void register_shrinker(struct shrinker *); +extern void unregister_shrinker(struct shrinker *); /* * Some shared mappigns will want the pages marked read-only |