Root/drivers/staging/zram/zram.txt

Source at commit 8b74237fa21aee6caf700e5a23c89d67c999804e created 13 years 10 months ago.
By Nitin Gupta, Rename ramzswap to zram in documentation
1zram: Compressed RAM based block devices
2----------------------------------------
3
4Project home: http://compcache.googlecode.com/
5
6* Introduction
7
8The zram module creates RAM based block devices: /dev/ramX (X = 0, 1, ...).
9Pages written to these disks are compressed and stored in memory itself.
10These disks allow very fast I/O and compression provides good amounts of
11memory savings.
12
13See project home for use cases, performance numbers and a lot more.
14
15Individual zram devices are configured and initialized using zramconfig
16userspace utility as shown in examples below. See zramconfig man page for
17more details.
18
19* Usage
20
21Following shows a typical sequence of steps for using zram.
22
231) Load Modules:
24    modprobe zram num_devices=4
25    This creates 4 (uninitialized) devices: /dev/zram{0,1,2,3}
26    (num_devices parameter is optional. Default: 1)
27
282) Initialize:
29    Use zramconfig utility to configure and initialize individual
30    zram devices. For example:
31    zramconfig /dev/zram0 --init # uses default value of disksize_kb
32    zramconfig /dev/zram1 --disksize_kb=102400 # 100MB /dev/zram1
33
34    *See zramconfig man page for more details and examples*
35
363) Activate:
37    mkswap /dev/zram0
38    swapon /dev/zram0
39
40    mkfs.ext4 /dev/zram1
41    mount /dev/zram1 /tmp
42
434) Stats:
44    zramconfig /dev/zram0 --stats
45    zramconfig /dev/zram1 --stats
46
475) Deactivate:
48    swapoff /dev/zram0
49    umount /dev/zram1
50
516) Reset:
52    zramconfig /dev/zram0 --reset
53    zramconfig /dev/zram1 --reset
54    (This frees memory allocated for the given device).
55
56
57Please report any problems at:
58 - Mailing list: linux-mm-cc at laptop dot org
59 - Issue tracker: http://code.google.com/p/compcache/issues/list
60
61Nitin Gupta
62ngupta@vflare.org
63

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