diff --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI/testing/sysfs-block-zram
index 8aa0468416255bb85c2a97b1900f62d15ed2a5f3..0da9ed6b82ea91320926ce5e17f9777f185f84af 100644
--- a/Documentation/ABI/testing/sysfs-block-zram
+++ b/Documentation/ABI/testing/sysfs-block-zram
@@ -50,7 +50,6 @@ Description:
The failed_reads file is read-only and specifies the number of
failed reads happened on this device.
-
What: /sys/block/zram<id>/failed_writes
Date: February 2014
Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
@@ -58,6 +57,14 @@ Description:
The failed_writes file is read-only and specifies the number of
failed writes happened on this device.
+What: /sys/block/zram<id>/max_comp_streams
+Date: February 2014
+Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+ The max_comp_streams file is read-write and specifies the
+ number of backend's zcomp_strm compression streams (number of
+ concurrent compress operations).
+
What: /sys/block/zram<id>/notify_free
Date: August 2010
Contact: Nitin Gupta <ngupta@vflare.org>
diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt
index b31ac5e5d4b9291d741fb37a5b82e380bc4d2d70..aadfe60391b74643150b9a911f9fde8da8746abe 100644
--- a/Documentation/blockdev/zram.txt
+++ b/Documentation/blockdev/zram.txt
@@ -21,7 +21,28 @@ Following shows a typical sequence of steps for using zram.
This creates 4 devices: /dev/zram{0,1,2,3}
(num_devices parameter is optional. Default: 1)
-2) Set Disksize
+2) Set max number of compression streams
+ Compression backend may use up to max_comp_streams compression streams,
+ thus allowing up to max_comp_streams concurrent compression operations.
+ By default, compression backend uses single compression stream.
+
+ Examples:
+ #show max compression streams number
+ cat /sys/block/zram0/max_comp_streams
+
+ #set max compression streams number to 3
+ echo 3 > /sys/block/zram0/max_comp_streams
+
+Note:
+In order to enable compression backend's multi stream support max_comp_streams
+must be initially set to desired concurrency level before ZRAM device
+initialisation. Once the device initialised as a single stream compression
+backend (max_comp_streams equals to 0) changing the value of max_comp_streams
+will not take any effect, because single stream compression backend implemented
+as a special case and does not support dynamic max_comp_streams. Only multi
+stream backend supports dynamic max_comp_streams adjustment.
+
+3) Set Disksize
Set disk size by writing the value to sysfs node 'disksize'.
The value can be either in bytes or you can use mem suffixes.
Examples:
@@ -38,14 +59,14 @@ 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.
-3) Activate:
+4) Activate:
mkswap /dev/zram0
swapon /dev/zram0
mkfs.ext4 /dev/zram1
mount /dev/zram1 /tmp
-4) Stats:
+5) Stats:
Per-device statistics are exported as various nodes under
/sys/block/zram<id>/
disksize
@@ -60,11 +81,11 @@ size of the disk when not in use so a huge zram is wasteful.
compr_data_size
mem_used_total
-5) Deactivate:
+6) Deactivate:
swapoff /dev/zram0
umount /dev/zram1
-6) Reset:
+7) Reset:
Write any positive value to 'reset' sysfs node
echo 1 > /sys/block/zram0/reset
echo 1 > /sys/block/zram1/reset
diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
index 72e8071f9d73e1d74940bf2f06e89bfb1018fb3a..c06f75f547186a36346a1b89052c67aac0bbc81f 100644
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -24,6 +24,21 @@ struct zcomp_strm_single {
struct zcomp_strm *zstrm;
};
+/*
+ * multi zcomp_strm backend
+ */
+struct zcomp_strm_multi {
+ /* protect strm list */
+ spinlock_t strm_lock;
+ /* max possible number of zstrm streams */
+ int max_strm;
+ /* number of available zstrm streams */
+ int avail_strm;
+ /* list of available strms */
+ struct list_head idle_strm;
+ wait_queue_head_t strm_wait;
+};
+
static struct zcomp_backend *find_backend(const char *compress)
{
if (strncmp(compress, "lzo", 3) == 0)
@@ -62,6 +77,107 @@ static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp)
return zstrm;
}
+/*
+ * get idle zcomp_strm or wait until other process release
+ * (zcomp_strm_release()) one for us
+ */
+static struct zcomp_strm *zcomp_strm_multi_find(struct zcomp *comp)
+{
+ struct zcomp_strm_multi *zs = comp->stream;
+ struct zcomp_strm *zstrm;
+
+ while (1) {
+ spin_lock(&zs->strm_lock);
+ if (!list_empty(&zs->idle_strm)) {
+ zstrm = list_entry(zs->idle_strm.next,
+ struct zcomp_strm, list);
+ list_del(&zstrm->list);
+ spin_unlock(&zs->strm_lock);
+ return zstrm;
+ }
+ /* zstrm streams limit reached, wait for idle stream */
+ if (zs->avail_strm >= zs->max_strm) {
+ spin_unlock(&zs->strm_lock);
+ wait_event(zs->strm_wait, !list_empty(&zs->idle_strm));
+ continue;
+ }
+ /* allocate new zstrm stream */
+ zs->avail_strm++;
+ spin_unlock(&zs->strm_lock);
+
+ zstrm = zcomp_strm_alloc(comp);
+ if (!zstrm) {
+ spin_lock(&zs->strm_lock);
+ zs->avail_strm--;
+ spin_unlock(&zs->strm_lock);
+ wait_event(zs->strm_wait, !list_empty(&zs->idle_strm));
+ continue;
+ }
+ break;
+ }
+ return zstrm;
+}
+
+/* add stream back to idle list and wake up waiter or free the stream */
+static void zcomp_strm_multi_release(struct zcomp *comp, struct zcomp_strm *zstrm)
+{
+ struct zcomp_strm_multi *zs = comp->stream;
+
+ spin_lock(&zs->strm_lock);
+ if (zs->avail_strm <= zs->max_strm) {
+ list_add(&zstrm->list, &zs->idle_strm);
+ spin_unlock(&zs->strm_lock);
+ wake_up(&zs->strm_wait);
+ return;
+ }
+
+ zs->avail_strm--;
+ spin_unlock(&zs->strm_lock);
+ zcomp_strm_free(comp, zstrm);
+}
+
+static void zcomp_strm_multi_destroy(struct zcomp *comp)
+{
+ struct zcomp_strm_multi *zs = comp->stream;
+ struct zcomp_strm *zstrm;
+
+ while (!list_empty(&zs->idle_strm)) {
+ zstrm = list_entry(zs->idle_strm.next,
+ struct zcomp_strm, list);
+ list_del(&zstrm->list);
+ zcomp_strm_free(comp, zstrm);
+ }
+ kfree(zs);
+}
+
+static int zcomp_strm_multi_create(struct zcomp *comp, int max_strm)
+{
+ struct zcomp_strm *zstrm;
+ struct zcomp_strm_multi *zs;
+
+ comp->destroy = zcomp_strm_multi_destroy;
+ comp->strm_find = zcomp_strm_multi_find;
+ comp->strm_release = zcomp_strm_multi_release;
+ zs = kmalloc(sizeof(struct zcomp_strm_multi), GFP_KERNEL);
+ if (!zs)
+ return -ENOMEM;
+
+ comp->stream = zs;
+ spin_lock_init(&zs->strm_lock);
+ INIT_LIST_HEAD(&zs->idle_strm);
+ init_waitqueue_head(&zs->strm_wait);
+ zs->max_strm = max_strm;
+ zs->avail_strm = 1;
+
+ zstrm = zcomp_strm_alloc(comp);
+ if (!zstrm) {
+ kfree(zs);
+ return -ENOMEM;
+ }
+ list_add(&zstrm->list, &zs->idle_strm);
+ return 0;
+}
+
static struct zcomp_strm *zcomp_strm_single_find(struct zcomp *comp)
{
struct zcomp_strm_single *zs = comp->stream;
@@ -139,7 +255,7 @@ 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 max_strm)
{
struct zcomp *comp;
struct zcomp_backend *backend;
@@ -153,7 +269,11 @@ struct zcomp *zcomp_create(const char *compress)
return NULL;
comp->backend = backend;
- if (zcomp_strm_single_create(comp) != 0) {
+ if (max_strm > 1)
+ zcomp_strm_multi_create(comp, max_strm);
+ else
+ zcomp_strm_single_create(comp);
+ if (!comp->stream) {
kfree(comp);
return NULL;
}
diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h
index dc3500d842a37937c1178508e4dfb878a8afb4bc..2a36844461606a4f6616a37d81ada10f7d89d905 100644
--- a/drivers/block/zram/zcomp.h
+++ b/drivers/block/zram/zcomp.h
@@ -21,6 +21,8 @@ struct zcomp_strm {
* working memory)
*/
void *private;
+ /* used in multi stream backend, protected by backend strm_lock */
+ struct list_head list;
};
/* static compression backend */
@@ -47,7 +49,7 @@ struct zcomp {
void (*destroy)(struct zcomp *comp);
};
-struct zcomp *zcomp_create(const char *comp);
+struct zcomp *zcomp_create(const char *comp, int max_strm);
void zcomp_destroy(struct zcomp *comp);
struct zcomp_strm *zcomp_strm_find(struct zcomp *comp);
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 98823f9ca8b139cc14c52ef4191c663a89e63846..bdc7eb8c6df7474d61ac7f3ba930588733dbb9d0 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 */
@@ -537,7 +573,7 @@ static ssize_t disksize_store(struct device *dev,
goto out_free_meta;
}
- zram->comp = zcomp_create(default_compressor);
+ zram->comp = zcomp_create(default_compressor, zram->max_comp_streams);
if (!zram->comp) {
pr_info("Cannot initialise %s compressing backend\n",
default_compressor);
@@ -698,6 +734,8 @@ 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);
@@ -722,6 +760,7 @@ 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,
};
@@ -784,6 +823,7 @@ 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 45e04f7b713f791c63fea434f4a72ff84c7750eb..ccf36d11755ae751036904290bc07b913088dbf4 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