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| author | Sergey Senozhatsky <sergey.senozhatsky@gmail.com> | 2014-04-07 15:38:17 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-04-07 16:36:01 -0700 |
| commit | e46b8a030d76d3c94156c545c3f4c3676d813435 (patch) | |
| tree | 9629389f89d3086a6428ec6a8e47bc59ddfcf3ec /Documentation | |
| parent | fe8eb122c82b2049c460fc6df6e8583a2f935cff (diff) | |
| download | lwn-e46b8a030d76d3c94156c545c3f4c3676d813435.tar.gz lwn-e46b8a030d76d3c94156c545c3f4c3676d813435.zip | |
zram: make compression algorithm selection possible
Add and document `comp_algorithm' device attribute. This attribute allows
to show supported compression and currently selected compression
algorithms:
cat /sys/block/zram0/comp_algorithm
[lzo] lz4
and change selected compression algorithm:
echo lzo > /sys/block/zram0/comp_algorithm
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-block-zram | 8 | ||||
| -rw-r--r-- | Documentation/blockdev/zram.txt | 24 |
2 files changed, 27 insertions, 5 deletions
diff --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI/testing/sysfs-block-zram index 0da9ed6b82ea..70ec992514d0 100644 --- a/Documentation/ABI/testing/sysfs-block-zram +++ b/Documentation/ABI/testing/sysfs-block-zram @@ -65,6 +65,14 @@ Description: number of backend's zcomp_strm compression streams (number of concurrent compress operations). +What: /sys/block/zram<id>/comp_algorithm +Date: February 2014 +Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> +Description: + The comp_algorithm file is read-write and lets to show + available and selected compression algorithms, change + compression algorithm selection. + 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 aadfe60391b7..2604ffed51db 100644 --- a/Documentation/blockdev/zram.txt +++ b/Documentation/blockdev/zram.txt @@ -42,7 +42,21 @@ 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 +3) Select compression algorithm + Using comp_algorithm device attribute one can see available and + currently selected (shown in square brackets) compression algortithms, + change selected compression algorithm (once the device is initialised + there is no way to change compression algorithm). + + Examples: + #show supported compression algorithms + cat /sys/block/zram0/comp_algorithm + lzo [lz4] + + #select lzo compression algorithm + echo lzo > /sys/block/zram0/comp_algorithm + +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: @@ -59,14 +73,14 @@ 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. -4) Activate: +5) Activate: mkswap /dev/zram0 swapon /dev/zram0 mkfs.ext4 /dev/zram1 mount /dev/zram1 /tmp -5) Stats: +6) Stats: Per-device statistics are exported as various nodes under /sys/block/zram<id>/ disksize @@ -81,11 +95,11 @@ size of the disk when not in use so a huge zram is wasteful. compr_data_size mem_used_total -6) Deactivate: +7) Deactivate: swapoff /dev/zram0 umount /dev/zram1 -7) Reset: +8) Reset: Write any positive value to 'reset' sysfs node echo 1 > /sys/block/zram0/reset echo 1 > /sys/block/zram1/reset |