diff options
| author | David Rientjes <rientjes@google.com> | 2009-09-22 02:04:31 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-22 16:17:47 +0200 |
| commit | 4af5a2f770cc8575840ccb1514ec76ecb592985c (patch) | |
| tree | 7af18234d7d171a946925e65e987fd51648be3aa | |
| parent | flex_array: poison free elements (diff) | |
| download | linux-4af5a2f770cc8575840ccb1514ec76ecb592985c.tar.xz linux-4af5a2f770cc8575840ccb1514ec76ecb592985c.zip | |
flex_array: add flex_array_shrink function
Add a new function to the flex_array API:
int flex_array_shrink(struct flex_array *fa)
This function will free all unused second-level pages. Since elements are
now poisoned if they are not allocated with __GFP_ZERO, it's possible to
identify parts that consist solely of unused elements.
flex_array_shrink() returns the number of pages freed.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | include/linux/flex_array.h | 1 | ||||
| -rw-r--r-- | lib/flex_array.c | 40 |
2 files changed, 41 insertions, 0 deletions
diff --git a/include/linux/flex_array.h b/include/linux/flex_array.h index 3887b21f883f..f12401e485fe 100644 --- a/include/linux/flex_array.h +++ b/include/linux/flex_array.h @@ -46,5 +46,6 @@ int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src, gfp_t flags); int flex_array_clear(struct flex_array *fa, unsigned int element_nr); void *flex_array_get(struct flex_array *fa, unsigned int element_nr); +int flex_array_shrink(struct flex_array *fa); #endif /* _FLEX_ARRAY_H */ diff --git a/lib/flex_array.c b/lib/flex_array.c index e22d0e9776aa..1b03bb553410 100644 --- a/lib/flex_array.c +++ b/lib/flex_array.c @@ -291,3 +291,43 @@ void *flex_array_get(struct flex_array *fa, unsigned int element_nr) } return &part->elements[index_inside_part(fa, element_nr)]; } + +static int part_is_free(struct flex_array_part *part) +{ + int i; + + for (i = 0; i < sizeof(struct flex_array_part); i++) + if (part->elements[i] != FLEX_ARRAY_FREE) + return 0; + return 1; +} + +/** + * flex_array_shrink - free unused second-level pages + * + * Frees all second-level pages that consist solely of unused + * elements. Returns the number of pages freed. + * + * Locking must be provided by the caller. + */ +int flex_array_shrink(struct flex_array *fa) +{ + struct flex_array_part *part; + int max_part = nr_base_part_ptrs(); + int part_nr; + int ret = 0; + + if (elements_fit_in_base(fa)) + return ret; + for (part_nr = 0; part_nr < max_part; part_nr++) { + part = fa->parts[part_nr]; + if (!part) + continue; + if (part_is_free(part)) { + fa->parts[part_nr] = NULL; + kfree(part); + ret++; + } + } + return ret; +} |