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Subject[PATCHv7 5/7] zram: enable multi stream compression support in zram
Date
1) Introduce zram device attribute max_comp_streams to show and store
current zcomp's max number of zcomp streams (num_strm).

2) Extend zcomp zcomp_create() with `num_strm' parameter. `num_strm'
limits the number of zcomp_strm structs in compression backend's idle
list (max_comp_streams).

max_comp_streams used during initialisation as follows:
-- passing to zcomp_create() num_strm equals to 1 will initialise zcomp
using single compression stream zcomp_strm_single (mutex-based locking).
-- passing to zcomp_create() num_strm greater than 1 will initialise zcomp
using multi compression stream zcomp_strm_multi (spinlock-based locking).

default max_comp_streams value is 1, meaning that zram with single stream
will be initialised.

Later patch will introduce configuration knob to change max_comp_streams
on already initialised and used zcomp.

iozone -t 3 -R -r 16K -s 60M -I +Z

test base 1 strm (mutex) 3 strm (spinlock)
-----------------------------------------------------------------------
Initial write 589286.78 583518.39 718011.05
Rewrite 604837.97 596776.38 1515125.72
Random write 584120.11 595714.58 1388850.25
Pwrite 535731.17 541117.38 739295.27
Fwrite 1418083.88 1478612.72 1484927.06

Usage example:
set max_comp_streams to 4
echo 4 > /sys/block/zram0/max_comp_streams

show current max_comp_streams (default value is 1).
cat /sys/block/zram0/max_comp_streams

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
drivers/block/zram/zcomp.c | 9 +++++++--
drivers/block/zram/zcomp.h | 2 +-
drivers/block/zram/zram_drv.c | 42 +++++++++++++++++++++++++++++++++++++++++-
drivers/block/zram/zram_drv.h | 2 +-
4 files changed, 50 insertions(+), 5 deletions(-)

diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
index 6f238f5..1bcb70e 100644
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -258,8 +258,9 @@ void zcomp_destroy(struct zcomp *comp)
* if requested algorithm is not supported or in case
* of init error
*/
-struct zcomp *zcomp_create(const char *compress)
+struct zcomp *zcomp_create(const char *compress, int num_strm)
{
+ int ret;
struct zcomp *comp;
struct zcomp_backend *backend;

@@ -272,7 +273,11 @@ struct zcomp *zcomp_create(const char *compress)
return NULL;

comp->backend = backend;
- if (zcomp_strm_single_create(comp) != 0) {
+ if (num_strm > 1)
+ ret = zcomp_strm_multi_create(comp, num_strm);
+ else
+ ret = zcomp_strm_single_create(comp);
+ if (ret != 0) {
zcomp_destroy(comp);
return NULL;
}
diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h
index 861e04d..5514509 100644
--- a/drivers/block/zram/zcomp.h
+++ b/drivers/block/zram/zcomp.h
@@ -42,7 +42,7 @@ struct zcomp {
void (*destroy)(struct zcomp *comp);
};

-struct zcomp *zcomp_create(const char *comp);
+struct zcomp *zcomp_create(const char *comp, int num_strm);
void zcomp_destroy(struct zcomp *comp);

struct zcomp_strm *zcomp_strm_get(struct zcomp *comp);
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 569ff58..42b9c7f 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -108,6 +108,40 @@ static ssize_t mem_used_total_show(struct device *dev,
return sprintf(buf, "%llu\n", val);
}

+static ssize_t max_comp_streams_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ int val;
+ struct zram *zram = dev_to_zram(dev);
+
+ down_read(&zram->init_lock);
+ val = zram->max_comp_streams;
+ up_read(&zram->init_lock);
+
+ return sprintf(buf, "%d\n", val);
+}
+
+static ssize_t max_comp_streams_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t len)
+{
+ int num;
+ struct zram *zram = dev_to_zram(dev);
+
+ if (kstrtoint(buf, 0, &num))
+ return -EINVAL;
+ if (num < 1)
+ return -EINVAL;
+ down_write(&zram->init_lock);
+ if (init_done(zram)) {
+ up_write(&zram->init_lock);
+ pr_info("Can't set max_comp_streams for initialized device\n");
+ return -EBUSY;
+ }
+ zram->max_comp_streams = num;
+ 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)
@@ -502,6 +536,8 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
}

zcomp_destroy(zram->comp);
+ zram->max_comp_streams = 1;
+
zram_meta_free(zram->meta);
zram->meta = NULL;
/* Reset stats */
@@ -530,7 +566,7 @@ static ssize_t disksize_store(struct device *dev,
return -EBUSY;
}

- zram->comp = zcomp_create(default_compressor);
+ zram->comp = zcomp_create(default_compressor, zram->max_comp_streams);
if (!zram->comp) {
up_write(&zram->init_lock);
pr_info("Cannot initialise %s compressing backend\n",
@@ -693,6 +729,8 @@ 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(max_comp_streams, S_IRUGO | S_IWUSR,
+ max_comp_streams_show, max_comp_streams_store);

ZRAM_ATTR_RO(num_reads);
ZRAM_ATTR_RO(num_writes);
@@ -717,6 +755,7 @@ static struct attribute *zram_disk_attrs[] = {
&dev_attr_orig_data_size.attr,
&dev_attr_compr_data_size.attr,
&dev_attr_mem_used_total.attr,
+ &dev_attr_max_comp_streams.attr,
NULL,
};

@@ -779,6 +818,7 @@ static int create_device(struct zram *zram, int device_id)
}

zram->meta = NULL;
+ zram->max_comp_streams = 1;
return 0;

out_free_disk:
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 45e04f7..ccf36d1 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -99,7 +99,7 @@ struct zram {
* we can store in a disk.
*/
u64 disksize; /* bytes */
-
+ int max_comp_streams;
struct zram_stats stats;
};
#endif
--
1.9.0.291.g027825b


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