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zram: remove max_comp_streams device attr

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max_comp_streams device attribute has been defunct since May 2016 when
zram switched to per-CPU compression streams, remove it.

Link: https://lkml.kernel.org/r/20250303022425.285971-5-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Kairui Song <ryncsn@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Yosry Ahmed <yosry.ahmed@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Sergey Senozhatsky
2025-03-03 11:03:13 +09:00
committed by Andrew Morton
parent be656187b8
commit 4127e13c93
3 changed files with 10 additions and 57 deletions
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36
Documentation/admin-guide/blockdev/zram.rst
View File

@@ -54,7 +54,7 @@ The list of possible return codes:
If you use 'echo', the returned value is set by the 'echo' utility,
and, in general case, something like::
echo 3 > /sys/block/zram0/max_comp_streams
echo foo > /sys/block/zram0/comp_algorithm
if [ $? -ne 0 ]; then
handle_error
fi
@@ -73,21 +73,7 @@ This creates 4 devices: /dev/zram{0,1,2,3}
num_devices parameter is optional and tells zram how many devices should be
pre-created. Default: 1.
2) Set max number of compression streams
========================================
Regardless of the value passed to this attribute, ZRAM will always
allocate multiple compression streams - one per online CPU - thus
allowing several concurrent compression operations. The number of
allocated compression streams goes down when some of the CPUs
become offline. There is no single-compression-stream mode anymore,
unless you are running a UP system or have only 1 CPU online.
To find out how many streams are currently available::
cat /sys/block/zram0/max_comp_streams
3) Select compression algorithm
2) Select compression algorithm
===============================
Using comp_algorithm device attribute one can see available and
@@ -107,7 +93,7 @@ Examples::
For the time being, the `comp_algorithm` content shows only compression
algorithms that are supported by zram.
4) Set compression algorithm parameters: Optional
3) Set compression algorithm parameters: Optional
=================================================
Compression algorithms may support specific parameters which can be
@@ -138,7 +124,7 @@ better the compression ratio, it even can take negatives values for some
algorithms), for other algorithms `level` is acceleration level (the higher
the value the lower the compression ratio).
5) Set Disksize
4) Set Disksize
===============
Set disk size by writing the value to sysfs node 'disksize'.
@@ -158,7 +144,7 @@ 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.
6) Set memory limit: Optional
5) Set memory limit: Optional
=============================
Set memory limit by writing the value to sysfs node 'mem_limit'.
@@ -177,7 +163,7 @@ Examples::
# To disable memory limit
echo 0 > /sys/block/zram0/mem_limit
7) Activate
6) Activate
===========
::
@@ -188,7 +174,7 @@ Examples::
mkfs.ext4 /dev/zram1
mount /dev/zram1 /tmp
8) Add/remove zram devices
7) Add/remove zram devices
==========================
zram provides a control interface, which enables dynamic (on-demand) device
@@ -208,7 +194,7 @@ execute::
echo X > /sys/class/zram-control/hot_remove
9) Stats
8) Stats
========
Per-device statistics are exported as various nodes under /sys/block/zram<id>/
@@ -228,8 +214,6 @@ mem_limit WO specifies the maximum amount of memory ZRAM can
writeback_limit WO specifies the maximum amount of write IO zram
can write out to backing device as 4KB unit
writeback_limit_enable RW show and set writeback_limit feature
max_comp_streams RW the number of possible concurrent compress
operations
comp_algorithm RW show and change the compression algorithm
algorithm_params WO setup compression algorithm parameters
compact WO trigger memory compaction
@@ -310,7 +294,7 @@ a single line of text and contains the following stats separated by whitespace:
Unit: 4K bytes
============== =============================================================
10) Deactivate
9) Deactivate
==============
::
@@ -318,7 +302,7 @@ a single line of text and contains the following stats separated by whitespace:
swapoff /dev/zram0
umount /dev/zram1
11) Reset
10) Reset
=========
Write any positive value to 'reset' sysfs node::