path: root/Documentation/blockdev
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authorMinchan Kim <minchan@kernel.org>2014-10-09 15:29:53 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-10-09 22:26:02 -0400
commit9ada9da9573f3460b156b7755c093e30b258eacb (patch)
tree45d38673aa9bc81b99131a3a3c5e1e97292bb5f5 /Documentation/blockdev
parent722cdc17232f0f684011407f7cf3c40d39457971 (diff)
zram: zram memory size limitation
Since zram has no control feature to limit memory usage, it makes hard to manage system memrory. This patch adds new knob "mem_limit" via sysfs to set up the a limit so that zram could fail allocation once it reaches the limit. In addition, user could change the limit in runtime so that he could manage the memory more dynamically. Initial state is no limit so it doesn't break old behavior. [akpm@linux-foundation.org: fix typo, per Sergey] Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: <juno.choi@lge.com> Cc: <seungho1.park@lge.com> Cc: Luigi Semenzato <semenzato@google.com> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Seth Jennings <sjennings@variantweb.net> Cc: David Horner <ds2horner@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/blockdev')
1 files changed, 20 insertions, 4 deletions
diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt
index 0595c3f56ccf..82c6a41116db 100644
--- a/Documentation/blockdev/zram.txt
+++ b/Documentation/blockdev/zram.txt
@@ -74,14 +74,30 @@ 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.
-5) Activate:
+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
+6) Activate:
mkswap /dev/zram0
swapon /dev/zram0
mkfs.ext4 /dev/zram1
mount /dev/zram1 /tmp
-6) Stats:
+7) Stats:
Per-device statistics are exported as various nodes under
@@ -96,11 +112,11 @@ size of the disk when not in use so a huge zram is wasteful.
-7) Deactivate:
+8) Deactivate:
swapoff /dev/zram0
umount /dev/zram1
-8) Reset:
+9) Reset:
Write any positive value to 'reset' sysfs node
echo 1 > /sys/block/zram0/reset
echo 1 > /sys/block/zram1/reset

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