Linux-libre 4.8.2-gnupck-4.8.2-gnu

1 files changed, 46 insertions, 36 deletions

diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt
index 13100fb3c..0535ae1f7 100644
--- a/Documentation/blockdev/zram.txt
+++ b/Documentation/blockdev/zram.txt
@@ -59,23 +59,23 @@ num_devices parameter is optional and tells zram how many devices should be
 pre-created. Default: 1.
 
 2) Set max number of compression streams
-	Regardless the value passed to this attribute, ZRAM will always
-	allocate multiple compression streams - one per online CPUs - thus
-	allowing several concurrent compression operations. The number of
-	allocated compression streams goes down when some of the CPUs
-	become offline. There is no single-compression-stream mode anymore,
-	unless you are running a UP system or has only 1 CPU online.
-
-	To find out how many streams are currently available:
+Regardless the value passed to this attribute, ZRAM will always
+allocate multiple compression streams - one per online CPUs - thus
+allowing several concurrent compression operations. The number of
+allocated compression streams goes down when some of the CPUs
+become offline. There is no single-compression-stream mode anymore,
+unless you are running a UP system or has only 1 CPU online.
+
+To find out how many streams are currently available:
 	cat /sys/block/zram0/max_comp_streams
 
 3) Select compression algorithm
-	Using comp_algorithm device attribute one can see available and
-	currently selected (shown in square brackets) compression algorithms,
-	change selected compression algorithm (once the device is initialised
-	there is no way to change compression algorithm).
+Using comp_algorithm device attribute one can see available and
+currently selected (shown in square brackets) compression algorithms,
+change selected compression algorithm (once the device is initialised
+there is no way to change compression algorithm).
 
-	Examples:
+Examples:
 	#show supported compression algorithms
 	cat /sys/block/zram0/comp_algorithm
 	lzo [lz4]
@@ -83,17 +83,27 @@ pre-created. Default: 1.
 	#select lzo compression algorithm
 	echo lzo > /sys/block/zram0/comp_algorithm
 
+For the time being, the `comp_algorithm' content does not necessarily
+show every compression algorithm supported by the kernel. We keep this
+list primarily to simplify device configuration and one can configure
+a new device with a compression algorithm that is not listed in
+`comp_algorithm'. The thing is that, internally, ZRAM uses Crypto API
+and, if some of the algorithms were built as modules, it's impossible
+to list all of them using, for instance, /proc/crypto or any other
+method. This, however, has an advantage of permitting the usage of
+custom crypto compression modules (implementing S/W or H/W compression).
+
 4) 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:
-            # Initialize /dev/zram0 with 50MB disksize
-            echo $((50*1024*1024)) > /sys/block/zram0/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:
+	# Initialize /dev/zram0 with 50MB disksize
+	echo $((50*1024*1024)) > /sys/block/zram0/disksize
 
-            # Using mem suffixes
-            echo 256K > /sys/block/zram0/disksize
-            echo 512M > /sys/block/zram0/disksize
-            echo 1G > /sys/block/zram0/disksize
+	# Using mem suffixes
+	echo 256K > /sys/block/zram0/disksize
+	echo 512M > /sys/block/zram0/disksize
+	echo 1G > /sys/block/zram0/disksize
 
 Note:
 There is little point creating a zram of greater than twice the size of memory
@@ -101,20 +111,20 @@ 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.
 
 5) Set memory limit: Optional
-	Set memory limit by writing the value to sysfs node 'mem_limit'.
-	The value can be either in bytes or you can use mem suffixes.
-	In addition, you could change the value in runtime.
-	Examples:
-	    # limit /dev/zram0 with 50MB memory
-	    echo $((50*1024*1024)) > /sys/block/zram0/mem_limit
-
-	    # Using mem suffixes
-	    echo 256K > /sys/block/zram0/mem_limit
-	    echo 512M > /sys/block/zram0/mem_limit
-	    echo 1G > /sys/block/zram0/mem_limit
-
-	    # To disable memory limit
-	    echo 0 > /sys/block/zram0/mem_limit
+Set memory limit by writing the value to sysfs node 'mem_limit'.
+The value can be either in bytes or you can use mem suffixes.
+In addition, you could change the value in runtime.
+Examples:
+	# limit /dev/zram0 with 50MB memory
+	echo $((50*1024*1024)) > /sys/block/zram0/mem_limit
+
+	# Using mem suffixes
+	echo 256K > /sys/block/zram0/mem_limit
+	echo 512M > /sys/block/zram0/mem_limit
+	echo 1G > /sys/block/zram0/mem_limit
+
+	# To disable memory limit
+	echo 0 > /sys/block/zram0/mem_limit
 
 6) Activate:
 	mkswap /dev/zram0