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[PATCH] change gen_pool allocator to not touch managed memory

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Modify the gen_pool allocator (lib/genalloc.c) to utilize a bitmap scheme
instead of the buddy scheme.  The purpose of this change is to eliminate
the touching of the actual memory being allocated.

Since the change modifies the interface, a change to the uncached allocator
(arch/ia64/kernel/uncached.c) is also required.

Both Andrey Volkov and Jes Sorenson have expressed a desire that the
gen_pool allocator not write to the memory being managed. See the
following:

  http://marc.theaimsgroup.com/?l=linux-kernel&m=113518602713125&w=2
  http://marc.theaimsgroup.com/?l=linux-kernel&m=113533568827916&w=2

Signed-off-by: Dean Nelson <dcn@sgi.com>
Cc: Andrey Volkov <avolkov@varma-el.com>
Acked-by: Jes Sorensen <jes@trained-monkey.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Dean Nelson 2006-06-23 02:03:21 -07:00 • committed by Linus Torvalds
parent 833423143c
commit 929f97276b
4 changed files with 252 additions and 261 deletions
Download patch file Download diff file Expand all files Collapse all files

43
include/linux/genalloc.h
View file

@ -4,37 +4,32 @@
* Uses for this includes on-device special memory, uncached memory
* etc.
*
* This code is based on the buddy allocator found in the sym53c8xx_2
* driver, adapted for general purpose use.
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*/
#include <linux/spinlock.h>
#define ALLOC_MIN_SHIFT 5 /* 32 bytes minimum */
/*
* Link between free memory chunks of a given size.
*/
struct gen_pool_link {
struct gen_pool_link *next;
};
/*
* Memory pool descriptor.
* General purpose special memory pool descriptor.
*/
struct gen_pool {
spinlock_t lock;
unsigned long (*get_new_chunk)(struct gen_pool *);
struct gen_pool *next;
struct gen_pool_link *h;
unsigned long private;
int max_chunk_shift;
rwlock_t lock;
struct list_head chunks; /* list of chunks in this pool */
int min_alloc_order; /* minimum allocation order */
};
unsigned long gen_pool_alloc(struct gen_pool *poolp, int size);
void gen_pool_free(struct gen_pool *mp, unsigned long ptr, int size);
struct gen_pool *gen_pool_create(int nr_chunks, int max_chunk_shift,
unsigned long (*fp)(struct gen_pool *),
unsigned long data);
/*
* General purpose special memory pool chunk descriptor.
*/
struct gen_pool_chunk {
spinlock_t lock;
struct list_head next_chunk; /* next chunk in pool */
unsigned long start_addr; /* starting address of memory chunk */
unsigned long end_addr; /* ending address of memory chunk */
unsigned long bits[0]; /* bitmap for allocating memory chunk */
};
extern struct gen_pool *gen_pool_create(int, int);
extern int gen_pool_add(struct gen_pool *, unsigned long, size_t, int);
extern unsigned long gen_pool_alloc(struct gen_pool *, size_t);
extern void gen_pool_free(struct gen_pool *, unsigned long, size_t);