[PATCHv2 2/2] zram: use zram_comp compressing backends

From: Sergey Senozhatsky
Date: Thu Jan 30 2014 - 14:32:04 EST

1) Use zram_comp in zram instead of direct LZO calls.

2) Introduce Kconfig ZRAM_LZO_COMPRESS and ZRAM_LZ4_COMPRESS
options to enable/disable LZO and LZ4 backends respectively.

3) Add compressor device attr that allows to list and select
compression algorithms.

usage example:
List available compression algorithms (currently selected
one is LZO):
cat /sys/block/zram0/compressor
<lzo> lz4

Change compression algorithm to LZ4:
echo lz4 > /sys/block/zram0/compressor
cat /sys/block/zram0/compressor
lzo <lz4>

iozone test `buffer_lock mutex' vs `single workmem and spinlock'
(each test was performed on cold, freashly created zram device,
ext4 file system, LZO):
./iozone -t -T -R -l 3 -u 3 -r 16K -s 60M -I +Z
test unpatÑhed patched
-------------------------------------------------
Initial write: 341274.03 | 465984.82
Rewrite: 527752.14 | 587844.27
Read: 2668083.00 | 3527865.95
Re-read: 2479428.12 | 3497152.56
Reverse Read: 1563745.16 | 2463020.33
Stride read: 1916311.84 | 2675575.14
Random read: 2099906.09 | 2758833.45
Mixed workload: 1631288.54 | 2439302.68
Random write: 428555.50 | 578720.39
Pwrite: 339857.66 | 415078.43
Pread: 1523965.55 | 1417191.77
Fwrite: 1571574.03 | 1447609.02
Fread: 5449851.44 | 5563909.53

./iozone -t -T -R -l 3 -u 3 -r 16K -s 60M -I +Z
test unpatÑhed patched
-------------------------------------------------
Initial write: 435205.70 | 513995.38
Rewrite: 617956.68 | 600445.49
Read: 3379175.66 | 3354820.31
Re-read: 3344446.66 | 3484581.59
Reverse Read: 2215915.09 | 2689347.80
Stride read: 2570020.28 | 2797849.55
Random read: 2751191.27 | 2830580.06
Mixed workload: 1647681.38 | 2382402.29
Random write: 591968.77 | 597967.23
Pwrite: 441869.31 | 526409.72
Pread: 1530294.05 | 1466025.38
Fwrite: 1634969.22 | 1757762.27
Fread: 4782938.06 | 5643076.25

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
---
drivers/block/zram/Kconfig | 20 ++++++++-
drivers/block/zram/Makefile | 6 ++-
drivers/block/zram/zram_drv.c | 96 ++++++++++++++++++++++++++++---------------
drivers/block/zram/zram_drv.h | 8 ++--
4 files changed, 90 insertions(+), 40 deletions(-)

diff --git a/drivers/block/zram/Kconfig b/drivers/block/zram/Kconfig
index 3450be8..4de410d 100644
--- a/drivers/block/zram/Kconfig
+++ b/drivers/block/zram/Kconfig
@@ -1,8 +1,6 @@
config ZRAM
tristate "Compressed RAM block device support"
depends on BLOCK && SYSFS && ZSMALLOC
- select LZO_COMPRESS
- select LZO_DECOMPRESS
default n
help
Creates virtual block devices called /dev/zramX (X = 0, 1, ...).
@@ -15,6 +13,24 @@ config ZRAM

See zram.txt for more information.

+config ZRAM_LZO_COMPRESS
+ bool "Compressed RAM LZO support"
+ depends on ZRAM
+ select LZO_COMPRESS
+ select LZO_DECOMPRESS
+ default y
+ help
+ This option adds LZO compression algorithm support.
+
+config ZRAM_LZ4_COMPRESS
+ bool "Compressed RAM LZ4 support"
+ depends on ZRAM
+ select LZ4_COMPRESS
+ select LZ4_DECOMPRESS
+ default n
+ help
+ This option adds LZ4 compression algorithm support.
+
config ZRAM_DEBUG
bool "Compressed RAM block device debug support"
depends on ZRAM
diff --git a/drivers/block/zram/Makefile b/drivers/block/zram/Makefile
index cb0f9ce..c649600 100644
--- a/drivers/block/zram/Makefile
+++ b/drivers/block/zram/Makefile
@@ -1,3 +1,7 @@
-zram-y := zram_drv.o
+zram-y := zram_comp.o zram_drv.o
+
+zram-$(CONFIG_ZRAM_LZO_COMPRESS) += zcomp_lzo.o
+
+zram-$(CONFIG_ZRAM_LZ4_COMPRESS) += zcomp_lz4.o

obj-$(CONFIG_ZRAM) += zram.o
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 9baac5b..46b1a44 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -29,15 +29,14 @@
#include <linux/genhd.h>
#include <linux/highmem.h>
#include <linux/slab.h>
-#include <linux/lzo.h>
#include <linux/string.h>
-#include <linux/vmalloc.h>

#include "zram_drv.h"

/* Globals */
static int zram_major;
static struct zram *zram_devices;
+static const char *default_compressor = "lzo";

/* Module params (documentation at end) */
static unsigned int num_devices = 1;
@@ -108,6 +107,39 @@ static ssize_t mem_used_total_show(struct device *dev,
return sprintf(buf, "%llu\n", val);
}

+static ssize_t compressor_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct zram *zram = dev_to_zram(dev);
+ ssize_t sz = 0;
+ down_read(&zram->init_lock);
+ sz = zcomp_available_show(zram->comp, buf);
+ up_read(&zram->init_lock);
+ return sz;
+}
+
+static ssize_t compressor_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t len)
+{
+ struct zram *zram = dev_to_zram(dev);
+
+ down_write(&zram->init_lock);
+ if (init_done(zram) || zram->comp) {
+ up_write(&zram->init_lock);
+ pr_info("Cannot change compressor for initialized device\n");
+ return -EBUSY;
+ }
+
+ zram->comp = zcomp_create(buf);
+ if (!zram->comp) {
+ up_write(&zram->init_lock);
+ pr_info("Cannot initialise compressing backend");
+ return -EINVAL;
+ }
+ up_write(&zram->init_lock);
+ return len;
+}
+
/* flag operations needs meta->tb_lock */
static int zram_test_flag(struct zram_meta *meta, u32 index,
enum zram_pageflags flag)
@@ -160,8 +192,6 @@ static inline int valid_io_request(struct zram *zram, struct bio *bio)
static void zram_meta_free(struct zram_meta *meta)
{
zs_destroy_pool(meta->mem_pool);
- kfree(meta->compress_workmem);
- free_pages((unsigned long)meta->compress_buffer, 1);
vfree(meta->table);
kfree(meta);
}
@@ -173,22 +203,11 @@ static struct zram_meta *zram_meta_alloc(u64 disksize)
if (!meta)
goto out;

- meta->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
- if (!meta->compress_workmem)
- goto free_meta;
-
- meta->compress_buffer =
- (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
- if (!meta->compress_buffer) {
- pr_err("Error allocating compressor buffer space\n");
- goto free_workmem;
- }
-
num_pages = disksize >> PAGE_SHIFT;
meta->table = vzalloc(num_pages * sizeof(*meta->table));
if (!meta->table) {
pr_err("Error allocating zram address table\n");
- goto free_buffer;
+ goto free_meta;
}

meta->mem_pool = zs_create_pool(GFP_NOIO | __GFP_HIGHMEM);
@@ -198,15 +217,10 @@ static struct zram_meta *zram_meta_alloc(u64 disksize)
}

rwlock_init(&meta->tb_lock);
- mutex_init(&meta->buffer_lock);
return meta;

free_table:
vfree(meta->table);
-free_buffer:
- free_pages((unsigned long)meta->compress_buffer, 1);
-free_workmem:
- kfree(meta->compress_workmem);
free_meta:
kfree(meta);
meta = NULL;
@@ -280,7 +294,7 @@ static void zram_free_page(struct zram *zram, size_t index)

static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
{
- int ret = LZO_E_OK;
+ int ret = 0;
size_t clen = PAGE_SIZE;
unsigned char *cmem;
struct zram_meta *meta = zram->meta;
@@ -301,12 +315,12 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
if (size == PAGE_SIZE)
copy_page(mem, cmem);
else
- ret = lzo1x_decompress_safe(cmem, size, mem, &clen);
+ ret = zram->comp->decompress(cmem, size, mem, &clen);
zs_unmap_object(meta->mem_pool, handle);
read_unlock(&meta->tb_lock);

/* Should NEVER happen. Return bio error if it does. */
- if (unlikely(ret != LZO_E_OK)) {
+ if (unlikely(ret)) {
pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
atomic64_inc(&zram->stats.failed_reads);
return ret;
@@ -349,7 +363,7 @@ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,

ret = zram_decompress_page(zram, uncmem, index);
/* Should NEVER happen. Return bio error if it does. */
- if (unlikely(ret != LZO_E_OK))
+ if (unlikely(ret))
goto out_cleanup;

if (is_partial_io(bvec))
@@ -374,11 +388,10 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
struct page *page;
unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
struct zram_meta *meta = zram->meta;
+ struct zcomp_workmem *wm;
bool locked = false;

page = bvec->bv_page;
- src = meta->compress_buffer;
-
if (is_partial_io(bvec)) {
/*
* This is a partial IO. We need to read the full page
@@ -394,7 +407,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
goto out;
}

- mutex_lock(&meta->buffer_lock);
+ wm = zram->comp->workmem_get(zram->comp);
+ src = wm->buf;
locked = true;
user_mem = kmap_atomic(page);

@@ -420,15 +434,14 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
goto out;
}

- ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
- meta->compress_workmem);
+ ret = zram->comp->compress(uncmem, PAGE_SIZE, src, &clen, wm->mem);
if (!is_partial_io(bvec)) {
kunmap_atomic(user_mem);
user_mem = NULL;
uncmem = NULL;
}

- if (unlikely(ret != LZO_E_OK)) {
+ if (unlikely(ret)) {
pr_err("Compression failed! err=%d\n", ret);
goto out;
}
@@ -457,6 +470,8 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
memcpy(cmem, src, clen);
}

+ zram->comp->workmem_put(zram->comp, wm);
+ locked = false;
zs_unmap_object(meta->mem_pool, handle);

/*
@@ -475,10 +490,9 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
atomic64_inc(&zram->stats.pages_stored);
out:
if (locked)
- mutex_unlock(&meta->buffer_lock);
+ zram->comp->workmem_put(zram->comp, wm);
if (is_partial_io(bvec))
kfree(uncmem);
-
if (ret)
atomic64_inc(&zram->stats.failed_writes);
return ret;
@@ -522,6 +536,10 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
zs_free(meta->mem_pool, handle);
}

+ if (zram->comp)
+ zcomp_destroy(zram->comp);
+ zram->comp = NULL;
+
zram_meta_free(zram->meta);
zram->meta = NULL;
/* Reset stats */
@@ -550,6 +568,14 @@ static ssize_t disksize_store(struct device *dev,
return -EBUSY;
}

+ if (!zram->comp)
+ zram->comp = zcomp_create(default_compressor);
+ if (!zram->comp) {
+ up_write(&zram->init_lock);
+ pr_info("Cannot initialise compressing backend\n");
+ return -EINVAL;
+ }
+
disksize = PAGE_ALIGN(disksize);
zram->meta = zram_meta_alloc(disksize);
if (!zram->meta) {
@@ -704,6 +730,8 @@ static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL);
static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store);
static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL);
static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
+static DEVICE_ATTR(compressor, S_IRUGO | S_IWUSR,
+ compressor_show, compressor_store);

ZRAM_ATTR_RO(num_reads);
ZRAM_ATTR_RO(num_writes);
@@ -718,6 +746,7 @@ static struct attribute *zram_disk_attrs[] = {
&dev_attr_disksize.attr,
&dev_attr_initstate.attr,
&dev_attr_reset.attr,
+ &dev_attr_compressor.attr,
&dev_attr_num_reads.attr,
&dev_attr_num_writes.attr,
&dev_attr_failed_reads.attr,
@@ -790,6 +819,7 @@ static int create_device(struct zram *zram, int device_id)
}

zram->meta = NULL;
+ zram->comp = NULL;
return 0;

out_free_disk:
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 1d5b1f5..a2e17d7 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -16,9 +16,10 @@
#define _ZRAM_DRV_H_

#include <linux/spinlock.h>
-#include <linux/mutex.h>
#include <linux/zsmalloc.h>

+#include "zram_comp.h"
+
/*
* Some arbitrary value. This is just to catch
* invalid value for num_devices module parameter.
@@ -81,17 +82,16 @@ struct zram_stats {

struct zram_meta {
rwlock_t tb_lock; /* protect table */
- void *compress_workmem;
- void *compress_buffer;
struct table *table;
struct zs_pool *mem_pool;
- struct mutex buffer_lock; /* protect compress buffers */
};

struct zram {
struct zram_meta *meta;
struct request_queue *queue;
struct gendisk *disk;
+ struct zram_comp *comp;
+
/* Prevent concurrent execution of device init, reset and R/W request */
struct rw_semaphore init_lock;
/*
--
1.9.rc1.183.g614c158

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