From: Zeev Tarantov <zeev.tarantov@xxxxxxxxx>
Zram currently uses LZO compression. With Snappy, it uses less CPU time and is
thus more useful. The sacrifice in compression ratio is small.
Zram's LZO and Snappy support can be independently enabled at compile time and
each zram device can switch between compression methods when unused.
When only a single compression method was enabled at compile time, no idirection
penalty is incurred.
Signed-off-by: Zeev Tarantov <zeev.tarantov@xxxxxxxxx>
---
drivers/staging/zram/Kconfig | 14 ++++-
drivers/staging/zram/zram_drv.c | 103 ++++++++++++++++++++++++++++++++-----
drivers/staging/zram/zram_drv.h | 30 +++++++++++
drivers/staging/zram/zram_sysfs.c | 58 +++++++++++++++++++++
4 files changed, 189 insertions(+), 16 deletions(-)
diff --git a/drivers/staging/zram/Kconfig b/drivers/staging/zram/Kconfig
index 3bec4db..9ad4716 100644
--- a/drivers/staging/zram/Kconfig
+++ b/drivers/staging/zram/Kconfig
@@ -6,8 +6,6 @@ config ZRAM
tristate "Compressed RAM block device support"
depends on BLOCK && SYSFS
select XVMALLOC
- select LZO_COMPRESS
- select LZO_DECOMPRESS
default n
help
Creates virtual block devices called /dev/zramX (X = 0, 1, ...).
@@ -28,3 +26,15 @@ config ZRAM_DEBUG
help
This option adds additional debugging code to the compressed
RAM block device driver.
+
+config ZRAM_LZO
+ bool "LZO compression"
+ default y
+ depends on ZRAM
+ select LZO_COMPRESS
+ select LZO_DECOMPRESS
+config ZRAM_SNAPPY
+ bool "Snappy compression"
+ depends on ZRAM
+ select SNAPPY_COMPRESS
+ select SNAPPY_DECOMPRESS
diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index aab4ec4..8c9da73 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -29,12 +29,90 @@
#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"
+#if defined(CONFIG_ZRAM_LZO)
+#include <linux/lzo.h>
+#ifdef MULTIPLE_COMPRESSORS
+static const struct zram_compressor lzo_compressor = {
+ .name = "LZO",
+ .workmem_bytes = LZO1X_MEM_COMPRESS,
+ .compress = &lzo1x_1_compress,
+ .decompress = &lzo1x_decompress_safe
+};
+#else /* !MULTIPLE_COMPRESSORS */
+#define WMSIZE LZO1X_MEM_COMPRESS
+#define COMPRESS(s, sl, d, dl, wm) \
+ lzo1x_1_compress(s, sl, d, dl, wm)
+#define DECOMPRESS(s, sl, d, dl) \
+ lzo1x_decompress_safe(s, sl, d, dl)
+#endif /* !MULTIPLE_COMPRESSORS */
+#endif /* defined(CONFIG_ZRAM_LZO) */
+
+#if defined(CONFIG_ZRAM_SNAPPY)
+#include "../snappy/csnappy.h" /* if built in drivers/staging */
+#define WMSIZE_ORDER ((PAGE_SHIFT > 14) ? (15) : (PAGE_SHIFT+1))
+static int
+snappy_compress_(
+ const unsigned char *src,
+ size_t src_len,
+ unsigned char *dst,
+ size_t *dst_len,
+ void *workmem)
+{
+ const unsigned char *end = csnappy_compress_fragment(
+ src, (uint32_t)src_len, dst, workmem, WMSIZE_ORDER);
+ *dst_len = end - dst;
+ return 0;
+}
+static int
+snappy_decompress_(
+ const unsigned char *src,
+ size_t src_len,
+ unsigned char *dst,
+ size_t *dst_len)
+{
+ uint32_t dst_len_ = (uint32_t)*dst_len;
+ int ret = csnappy_decompress_noheader(src, src_len, dst, &dst_len_);
+ *dst_len = (size_t)dst_len_;
+ return ret;
+}
+#ifdef MULTIPLE_COMPRESSORS
+static const struct zram_compressor snappy_compressor = {
+ .name = "SNAPPY",
+ .workmem_bytes = (1 << WMSIZE_ORDER),
+ .compress = &snappy_compress_,
+ .decompress = &snappy_decompress_
+};
+#else /* !MULTIPLE_COMPRESSORS */
+#define WMSIZE (1 << WMSIZE_ORDER)
+#define COMPRESS(s, sl, d, dl, wm) \
+ snappy_compress_(s, sl, d, dl, wm)
+#define DECOMPRESS(s, sl, d, dl) \
+ snappy_decompress_(s, sl, d, dl)
+#endif /* !MULTIPLE_COMPRESSORS */
+#endif /* defined(CONFIG_ZRAM_SNAPPY) */
+
+#ifdef MULTIPLE_COMPRESSORS
+const struct zram_compressor * const zram_compressors[] = {
+#if defined(CONFIG_ZRAM_LZO)
+ &lzo_compressor,
+#endif
+#if defined(CONFIG_ZRAM_SNAPPY)
+ &snappy_compressor,
+#endif
+ NULL
+};
+#define WMSIZE (zram->compressor->workmem_bytes)
+#define COMPRESS(s, sl, d, dl, wm) \
+ (zram->compressor->compress(s, sl, d, dl, wm))
+#define DECOMPRESS(s, sl, d, dl) \
+ (zram->compressor->decompress(s, sl, d, dl))
+#endif /* MULTIPLE_COMPRESSORS */
+
/* Globals */
static int zram_major;
struct zram *devices;
@@ -251,7 +329,7 @@ static void zram_read(struct zram *zram, struct bio *bio)
cmem = kmap_atomic(zram->table[index].page, KM_USER1) +
zram->table[index].offset;
- ret = lzo1x_decompress_safe(
+ ret = DECOMPRESS(
cmem + sizeof(*zheader),
xv_get_object_size(cmem) - sizeof(*zheader),
user_mem, &clen);
@@ -260,7 +338,7 @@ static void zram_read(struct zram *zram, struct bio *bio)
kunmap_atomic(cmem, KM_USER1);
/* 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);
zram_stat64_inc(zram, &zram->stats.failed_reads);
@@ -289,7 +367,6 @@ static void zram_write(struct zram *zram, struct bio *bio)
index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
bio_for_each_segment(bvec, bio, i) {
- int ret;
u32 offset;
size_t clen;
struct zobj_header *zheader;
@@ -319,18 +396,11 @@ static void zram_write(struct zram *zram, struct bio *bio)
continue;
}
- ret = lzo1x_1_compress(user_mem, PAGE_SIZE, src, &clen,
- zram->compress_workmem);
+ COMPRESS(user_mem, PAGE_SIZE, src, &clen,
+ zram->compress_workmem);
kunmap_atomic(user_mem, KM_USER0);
- if (unlikely(ret != LZO_E_OK)) {
- mutex_unlock(&zram->lock);
- pr_err("Compression failed! err=%d\n", ret);
- zram_stat64_inc(zram, &zram->stats.failed_writes);
- goto out;
- }
-
/*
* Page is incompressible. Store it as-is (uncompressed)
* since we do not want to return too many disk write
@@ -511,7 +581,7 @@ int zram_init_device(struct zram *zram)
zram_set_disksize(zram, totalram_pages << PAGE_SHIFT);
- zram->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
+ zram->compress_workmem = kzalloc(WMSIZE, GFP_KERNEL);
if (!zram->compress_workmem) {
pr_err("Error allocating compressor working memory!\n");
ret = -ENOMEM;
@@ -614,6 +684,11 @@ static int create_device(struct zram *zram, int device_id)
/* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
set_capacity(zram->disk, 0);
+ /* Can be changed using sysfs (/sys/block/zram<id>/compressor) */
+#ifdef MULTIPLE_COMPRESSORS
+ zram->compressor = zram_compressors[0];
+#endif
+
/*
* To ensure that we always get PAGE_SIZE aligned
* and n*PAGE_SIZED sized I/O requests.
diff --git a/drivers/staging/zram/zram_drv.h b/drivers/staging/zram/zram_drv.h
index 408b2c0..147df44 100644
--- a/drivers/staging/zram/zram_drv.h
+++ b/drivers/staging/zram/zram_drv.h
@@ -63,6 +63,13 @@ static const unsigned max_zpage_size = PAGE_SIZE / 4 * 3;
#define SECTORS_PER_PAGE (1 << SECTORS_PER_PAGE_SHIFT)
#define ZRAM_LOGICAL_BLOCK_SIZE 4096
+#if defined(CONFIG_ZRAM_LZO) + defined(CONFIG_ZRAM_SNAPPY) == 0
+#error At least one of CONFIG_ZRAM_LZO, CONFIG_ZRAM_SNAPPY must be defined!
+#endif
+#if defined(CONFIG_ZRAM_LZO) + defined(CONFIG_ZRAM_SNAPPY) > 1
+#define MULTIPLE_COMPRESSORS
+#endif
+
/* Flags for zram pages (table[page_no].flags) */
enum zram_pageflags {
/* Page is stored uncompressed */
@@ -100,6 +107,9 @@ struct zram_stats {
struct zram {
struct xv_pool *mem_pool;
+#ifdef MULTIPLE_COMPRESSORS
+ const struct zram_compressor *compressor;
+#endif
void *compress_workmem;
void *compress_buffer;
struct table *table;
@@ -129,4 +139,24 @@ extern struct attribute_group zram_disk_attr_group;
extern int zram_init_device(struct zram *zram);
extern void zram_reset_device(struct zram *zram);
+#ifdef MULTIPLE_COMPRESSORS
+struct zram_compressor {
+ const char *name;
+ int (*compress)(
+ const unsigned char *src,
+ size_t src_len,
+ unsigned char *dst,
+ size_t *dst_len,
+ void *workmem);
+ int (*decompress)(
+ const unsigned char *src,
+ size_t src_len,
+ unsigned char *dst,
+ size_t *dst_len);
+ unsigned workmem_bytes;
+};
+
+extern const struct zram_compressor * const zram_compressors[];
+#endif
+
#endif
diff --git a/drivers/staging/zram/zram_sysfs.c b/drivers/staging/zram/zram_sysfs.c
index a70cc01..6398fc6 100644
--- a/drivers/staging/zram/zram_sysfs.c
+++ b/drivers/staging/zram/zram_sysfs.c
@@ -72,6 +72,57 @@ static ssize_t disksize_store(struct device *dev,
return len;
}
+#ifdef MULTIPLE_COMPRESSORS
+static ssize_t compressor_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ char * const buf_base = buf;
+ const struct zram_compressor *p, *curr;
+ unsigned int i = 0;
+ struct zram *zram = dev_to_zram(dev);
+ curr = zram->compressor;
+ p = zram_compressors[i];
+ while (p) {
+ if (curr == p)
+ buf += sprintf(buf, "*");
+ buf += sprintf(buf, "%u - %s\n", i, p->name);
+ p = zram_compressors[++i];
+ }
+ return buf - buf_base;
+}
+
+static ssize_t compressor_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t len)
+{
+ const struct zram_compressor *p;
+ unsigned long requested;
+ unsigned int i = 0;
+ int ret;
+ struct zram *zram = dev_to_zram(dev);
+
+ if (zram->init_done) {
+ pr_info("Cannot change compressor for initialized device\n");
+ return -EBUSY;
+ }
+
+ ret = strict_strtoul(buf, 10, &requested);
+ if (ret)
+ return ret;
+
+ p = zram_compressors[i];
+ while (p && (i < requested))
+ p = zram_compressors[++i];
+
+ if (!p) {
+ pr_info("No compressor with index #%lu\n", requested);
+ return -EINVAL;
+ }
+
+ zram->compressor = p;
+ return len;
+}
+#endif /* MULTIPLE_COMPRESSORS */
+
static ssize_t initstate_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
@@ -188,6 +239,10 @@ static ssize_t mem_used_total_show(struct device *dev,
return sprintf(buf, "%llu\n", val);
}
+#ifdef MULTIPLE_COMPRESSORS
+static DEVICE_ATTR(compressor, S_IRUGO | S_IWUSR,
+ compressor_show, compressor_store);
+#endif
static DEVICE_ATTR(disksize, S_IRUGO | S_IWUSR,
disksize_show, disksize_store);
static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL);
@@ -202,6 +257,9 @@ static DEVICE_ATTR(compr_data_size, S_IRUGO, compr_data_size_show, NULL);
static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
static struct attribute *zram_disk_attrs[] = {
+#ifdef MULTIPLE_COMPRESSORS
+ &dev_attr_compressor.attr,
+#endif
&dev_attr_disksize.attr,
&dev_attr_initstate.attr,
&dev_attr_reset.attr,
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