aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorNitin Gupta <ngupta@vflare.org>2010-08-09 22:56:55 +0530
committerGreg Kroah-Hartman <gregkh@suse.de>2010-08-31 15:36:36 -0700
commit9b9913d80b2896ecd9e0a1a8f167ccad66fac79c (patch)
treeccebe583386a80c80cdf91324886f94b9878aa2a
parent484875adbc473041b7cf4ef0cb3f56a2ae44a448 (diff)
downloadmrst-s0i3-test-9b9913d80b2896ecd9e0a1a8f167ccad66fac79c.tar.gz
mrst-s0i3-test-9b9913d80b2896ecd9e0a1a8f167ccad66fac79c.tar.xz
mrst-s0i3-test-9b9913d80b2896ecd9e0a1a8f167ccad66fac79c.zip
Staging: zram: Update zram documentation
Update zram documentation to reflect transition form ioctl to sysfs interface. Signed-off-by: Nitin Gupta <ngupta@vflare.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/staging/zram/zram.txt58
1 files changed, 36 insertions, 22 deletions
diff --git a/drivers/staging/zram/zram.txt b/drivers/staging/zram/zram.txt
index 520edc1bea7..5f75d298756 100644
--- a/drivers/staging/zram/zram.txt
+++ b/drivers/staging/zram/zram.txt
@@ -5,33 +5,35 @@ Project home: http://compcache.googlecode.com/
* Introduction
-The zram module creates RAM based block devices: /dev/ramX (X = 0, 1, ...).
-Pages written to these disks are compressed and stored in memory itself.
-These disks allow very fast I/O and compression provides good amounts of
-memory savings.
+The zram module creates RAM based block devices named /dev/zram<id>
+(<id> = 0, 1, ...). Pages written to these disks are compressed and stored
+in memory itself. These disks allow very fast I/O and compression provides
+good amounts of memory savings. Some of the usecases include /tmp storage,
+use as swap disks, various caches under /var and maybe many more :)
-See project home for use cases, performance numbers and a lot more.
-
-Individual zram devices are configured and initialized using zramconfig
-userspace utility as shown in examples below. See zramconfig man page for
-more details.
+Statistics for individual zram devices are exported through sysfs nodes at
+/sys/block/zram<id>/
* Usage
Following shows a typical sequence of steps for using zram.
-1) Load Modules:
+1) Load Module:
modprobe zram num_devices=4
- This creates 4 (uninitialized) devices: /dev/zram{0,1,2,3}
+ This creates 4 devices: /dev/zram{0,1,2,3}
(num_devices parameter is optional. Default: 1)
-2) Initialize:
- Use zramconfig utility to configure and initialize individual
- zram devices. For example:
- zramconfig /dev/zram0 --init # uses default value of disksize_kb
- zramconfig /dev/zram1 --disksize_kb=102400 # 100MB /dev/zram1
+2) Set Disksize (Optional):
+ Set disk size by writing the value to sysfs node 'disksize'
+ (in bytes). If disksize is not given, default value of 25%
+ of RAM is used.
+
+ # Initialize /dev/zram0 with 50MB disksize
+ echo $((50*1024*1024)) > /sys/block/zram0/disksize
- *See zramconfig man page for more details and examples*
+ NOTE: disksize cannot be changed if the disk contains any
+ data. So, for such a disk, you need to issue 'reset' (see below)
+ before you can change its disksize.
3) Activate:
mkswap /dev/zram0
@@ -41,17 +43,29 @@ Following shows a typical sequence of steps for using zram.
mount /dev/zram1 /tmp
4) Stats:
- zramconfig /dev/zram0 --stats
- zramconfig /dev/zram1 --stats
+ Per-device statistics are exported as various nodes under
+ /sys/block/zram<id>/
+ disksize
+ num_reads
+ num_writes
+ invalid_io
+ notify_free
+ discard
+ zero_pages
+ orig_data_size
+ compr_data_size
+ mem_used_total
5) Deactivate:
swapoff /dev/zram0
umount /dev/zram1
6) Reset:
- zramconfig /dev/zram0 --reset
- zramconfig /dev/zram1 --reset
- (This frees memory allocated for the given device).
+ Write any positive value to 'reset' sysfs node
+ echo 1 > /sys/block/zram0/reset
+ echo 1 > /sys/block/zram1/reset
+
+ (This frees all the memory allocated for the given device).
Please report any problems at: