projects / deliverable / linux.git / blame
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|---|---|---|
| 00ac9ba0 NG |
1 | zram: Compressed RAM based block devices |
| 2 | ---------------------------------------- | |
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3 | |
| 4 | Project home: http://compcache.googlecode.com/ | |
| 5 | ||
| 6 | * Introduction | |
| 7 | ||
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8 | The zram module creates RAM based block devices: /dev/ramX (X = 0, 1, ...). |
| 9 | Pages written to these disks are compressed and stored in memory itself. | |
| 10 | These disks allow very fast I/O and compression provides good amounts of | |
| 11 | memory savings. | |
| 47f9afb3 | 12 | |
| 00ac9ba0 NG |
13 | See project home for use cases, performance numbers and a lot more. |
| 14 | ||
| 15 | Individual zram devices are configured and initialized using zramconfig | |
| 16 | userspace utility as shown in examples below. See zramconfig man page for | |
| 17 | more details. | |
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18 | |
| 19 | * Usage | |
| 20 | ||
| 00ac9ba0 | 21 | Following shows a typical sequence of steps for using zram. |
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22 | |
| 23 | 1) Load Modules: | |
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24 | modprobe zram num_devices=4 |
| 25 | This creates 4 (uninitialized) devices: /dev/zram{0,1,2,3} | |
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26 | (num_devices parameter is optional. Default: 1) |
| 27 | ||
| 28 | 2) Initialize: | |
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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 | |
| 47f9afb3 | 33 | |
| 00ac9ba0 | 34 | *See zramconfig man page for more details and examples* |
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35 | |
| 36 | 3) Activate: | |
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37 | mkswap /dev/zram0 |
| 38 | swapon /dev/zram0 | |
| 39 | ||
| 40 | mkfs.ext4 /dev/zram1 | |
| 41 | mount /dev/zram1 /tmp | |
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42 | |
| 43 | 4) Stats: | |
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44 | zramconfig /dev/zram0 --stats |
| 45 | zramconfig /dev/zram1 --stats | |
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46 | |
| 47 | 5) Deactivate: | |
| 00ac9ba0 NG |
48 | swapoff /dev/zram0 |
| 49 | umount /dev/zram1 | |
| 47f9afb3 NG |
50 | |
| 51 | 6) Reset: | |
| 00ac9ba0 NG |
52 | zramconfig /dev/zram0 --reset |
| 53 | zramconfig /dev/zram1 --reset | |
| 54 | (This frees memory allocated for the given device). | |
| 47f9afb3 NG |
55 | |
| 56 | ||
| 57 | Please 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 | ||
| 61 | Nitin Gupta | |
| 62 | ngupta@vflare.org |