Prev: [PATCH 00/10] zram: various improvements and cleanups
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From: Nitin Gupta on 9 Aug 2010 13:30
- xvmalloc: Remove unnecessary stat_{inc,dec} and increment
pages_stored directly
- xvmalloc: Initialize pointers with NULL instead of 0
- zram: Remove verbose message when use sets insane disksize
- zram: Mark some messages as pr_debug
- zram: Refine some comments

Signed-off-by: Nitin Gupta <ngupta(a)vflare.org>
---
drivers/staging/zram/xvmalloc.c | 22 ++++-------------
drivers/staging/zram/zram_drv.c | 49 +++++++++++++-------------------------
drivers/staging/zram/zram_drv.h | 26 ++++----------------
3 files changed, 28 insertions(+), 69 deletions(-)

diff --git a/drivers/staging/zram/xvmalloc.c b/drivers/staging/zram/xvmalloc.c
index 3fdbb8a..6268f65 100644
--- a/drivers/staging/zram/xvmalloc.c
+++ b/drivers/staging/zram/xvmalloc.c
@@ -20,16 +20,6 @@
#include "xvmalloc.h"
#include "xvmalloc_int.h"

-static void stat_inc(u64 *value)
-{
- *value = *value + 1;
-}
-
-static void stat_dec(u64 *value)
-{
- *value = *value - 1;
-}
-
static int test_flag(struct block_header *block, enum blockflags flag)
{
return block->prev & BIT(flag);
@@ -187,7 +177,7 @@ static void insert_block(struct xv_pool *pool, struct page *page, u32 offset,
slindex = get_index_for_insert(block->size);
flindex = slindex / BITS_PER_LONG;

- block->link.prev_page = 0;
+ block->link.prev_page = NULL;
block->link.prev_offset = 0;
block->link.next_page = pool->freelist[slindex].page;
block->link.next_offset = pool->freelist[slindex].offset;
@@ -217,7 +207,7 @@ static void remove_block_head(struct xv_pool *pool,

pool->freelist[slindex].page = block->link.next_page;
pool->freelist[slindex].offset = block->link.next_offset;
- block->link.prev_page = 0;
+ block->link.prev_page = NULL;
block->link.prev_offset = 0;

if (!pool->freelist[slindex].page) {
@@ -232,7 +222,7 @@ static void remove_block_head(struct xv_pool *pool,
*/
tmpblock = get_ptr_atomic(pool->freelist[slindex].page,
pool->freelist[slindex].offset, KM_USER1);
- tmpblock->link.prev_page = 0;
+ tmpblock->link.prev_page = NULL;
tmpblock->link.prev_offset = 0;
put_ptr_atomic(tmpblock, KM_USER1);
}
@@ -284,7 +274,7 @@ static int grow_pool(struct xv_pool *pool, gfp_t flags)
if (unlikely(!page))
return -ENOMEM;

- stat_inc(&pool->total_pages);
+ pool->total_pages++;

spin_lock(&pool->lock);
block = get_ptr_atomic(page, 0, KM_USER0);
@@ -361,8 +351,6 @@ int xv_malloc(struct xv_pool *pool, u32 size, struct page **page,

if (!*page) {
spin_unlock(&pool->lock);
- if (flags & GFP_NOWAIT)
- return -ENOMEM;
error = grow_pool(pool, flags);
if (unlikely(error))
return error;
@@ -472,7 +460,7 @@ void xv_free(struct xv_pool *pool, struct page *page, u32 offset)
spin_unlock(&pool->lock);

__free_page(page);
- stat_dec(&pool->total_pages);
+ pool->total_pages--;
return;
}

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index 0f9785f..42aa271 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -9,7 +9,7 @@
* Released under the terms of 3-clause BSD License
* Released under the terms of GNU General Public License Version 2.0
*
- * Project home: http://compcache.googlecode.com
+ * Project home: http://compcache.googlecode.com/
*/

#define KMSG_COMPONENT "zram"
@@ -130,33 +130,15 @@ static void zram_insert_obj(struct zram *zram, u32 index, struct page *page,
zram->table[index].addr = addr;
}

-static void zram_set_disksize(struct zram *zram, size_t totalram_bytes)
+static u64 zram_default_disksize(void)
{
- if (!zram->disksize) {
- pr_info(
- "disk size not provided. You can use disksize_kb module "
- "param to specify size.\nUsing default: (%u%% of RAM).\n",
- default_disksize_perc_ram
- );
- zram->disksize = default_disksize_perc_ram *
- (totalram_bytes / 100);
- }
+ u64 disksize;

- if (zram->disksize > 2 * (totalram_bytes)) {
- pr_info(
- "There is little point creating a zram of greater than "
- "twice the size of memory since we expect a 2:1 compression "
- "ratio. Note that zram uses about 0.1%% of the size of "
- "the disk when not in use so a huge zram is "
- "wasteful.\n"
- "\tMemory Size: %zu kB\n"
- "\tSize you selected: %llu kB\n"
- "Continuing anyway ...\n",
- totalram_bytes >> 10, zram->disksize
- );
- }
+ disksize = default_disksize_perc_ram *
+ (totalram_pages / 100);
+ disksize = (disksize << PAGE_SHIFT) & PAGE_MASK;

- zram->disksize &= PAGE_MASK;
+ return disksize;
}

static void zram_free_page(struct zram *zram, size_t index)
@@ -459,7 +441,7 @@ static int zram_make_request(struct request_queue *queue, struct bio *bio)
int ret = 0;
struct zram *zram = queue->queuedata;

- if (!valid_io_request(zram, bio)) {
+ if (unlikely(!valid_io_request(zram, bio))) {
zram_inc_stat(zram, ZRAM_STAT_INVALID_IO);
bio_io_error(bio);
return 0;
@@ -504,7 +486,7 @@ void zram_reset_device(struct zram *zram)
/* Reset stats */
memset(&zram->stats, 0, sizeof(zram->stats));

- zram->disksize = 0;
+ zram->disksize = zram_default_disksize();
mutex_unlock(&zram->init_lock);
}

@@ -520,7 +502,8 @@ int zram_init_device(struct zram *zram)
return 0;
}

- zram_set_disksize(zram, totalram_pages << PAGE_SHIFT);
+ if (!zram->disksize)
+ zram->disksize = zram_default_disksize();

num_pages = zram->disksize >> PAGE_SHIFT;
zram->table = vmalloc(num_pages * sizeof(*zram->table));
@@ -566,7 +549,8 @@ fail:
return ret;
}

-void zram_slot_free_notify(struct block_device *bdev, unsigned long index)
+static void zram_slot_free_notify(struct block_device *bdev,
+ unsigned long index)
{
struct zram *zram;

@@ -614,8 +598,9 @@ static int create_device(struct zram *zram, int device_id)
zram->disk->private_data = zram;
snprintf(zram->disk->disk_name, 16, "zram%d", device_id);

- /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
- set_capacity(zram->disk, 0);
+ /* Custom size can be set using syfs (/sys/block/zram<id>/disksize) */
+ zram->disksize = zram_default_disksize();
+ set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);

/*
* To ensure that we always get PAGE_SIZE aligned
@@ -739,7 +724,7 @@ static int __init zram_init(void)
}

/* Allocate the device array and initialize each one */
- pr_info("Creating %u devices ...\n", num_devices);
+ pr_debug("Creating %u devices ...\n", num_devices);
devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
if (!devices) {
ret = -ENOMEM;
diff --git a/drivers/staging/zram/zram_drv.h b/drivers/staging/zram/zram_drv.h
index bcc51ea..2cf36db 100644
--- a/drivers/staging/zram/zram_drv.h
+++ b/drivers/staging/zram/zram_drv.h
@@ -9,7 +9,7 @@
* Released under the terms of 3-clause BSD License
* Released under the terms of GNU General Public License Version 2.0
*
- * Project home: http://compcache.googlecode.com
+ * Project home: http://compcache.googlecode.com/
*/

#ifndef _ZRAM_DRV_H_
@@ -26,18 +26,6 @@
*/
static const unsigned max_num_devices = 32;

-/*
- * Stored at beginning of each compressed object.
- *
- * It stores back-reference to table entry which points to this
- * object. This is required to support memory defragmentation.
- */
-struct zobj_header {
-#if 0
- u32 table_idx;
-#endif
-};
-
/*-- Configurable parameters */

/* Default zram disk size: 25% of total RAM */
@@ -50,8 +38,7 @@ static const unsigned default_disksize_perc_ram = 25;
static const unsigned max_zpage_size = PAGE_SIZE / 8 * 7;

/*
- * NOTE: max_zpage_size must be less than or equal to:
- * XV_MAX_ALLOC_SIZE - sizeof(struct zobj_header)
+ * NOTE: max_zpage_size must be less than or equal to XV_MAX_ALLOC_SIZE
* otherwise, xv_malloc() would always return failure.
*/

@@ -92,16 +79,15 @@ struct zram {
struct table *table;
struct request_queue *queue;
struct gendisk *disk;
- int init_done;
+ unsigned int init_done;
/* Prevent concurrent execution of device init and reset */
struct mutex init_lock;
/*
* This is the limit on amount of *uncompressed* worth of data
- * we can store in a disk.
+ * we can store in a disk (in bytes).
*/
- u64 disksize; /* bytes */
-
- struct zram_stats_cpu *stats;
+ u64 disksize;
+ struct zram_stats_cpu *stats; /* percpu stats */
};

extern struct zram *devices;
--
1.7.2.1

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Prev: [PATCH 00/10] zram: various improvements and cleanups
Next: rcu,debug_core: allow the kernel debugger to reset the rcu stall timer