xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

mm/zswap: allow setting default status, compressor and allocator in Kconfig

Browse Source 
The compressed cache for swap pages (zswap) currently needs from 1 to 3
extra kernel command line parameters in order to make it work: it has to
be enabled by adding a "zswap.enabled=1" command line parameter and if one
wants a different compressor or pool allocator than the default lzo / zbud
combination then these choices also need to be specified on the kernel
command line in additional parameters.

Using a different compressor and allocator for zswap is actually pretty
common as guides often recommend using the lz4 / z3fold pair instead of
the default one.  In such case it is also necessary to remember to enable
the appropriate compression algorithm and pool allocator in the kernel
config manually.

Let's avoid the need for adding these kernel command line parameters and
automatically pull in the dependencies for the selected compressor
algorithm and pool allocator by adding an appropriate default switches to
Kconfig.

The default values for these options match what the code was using
previously as its defaults.

Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Vitaly Wool <vitaly.wool@konsulko.com>
Link: http://lkml.kernel.org/r/20200202000112.456103-1-mail@maciej.szmigiero.name
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Maciej S. Szmigiero
2020-04-06 20:08:03 -07:00
committed by Linus Torvalds
parent 4708f31885
commit bb8b93b5b6
3 changed files with 141 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
Documentation/vm/zswap.rst
View File

@@ -35,9 +35,11 @@ Zswap evicts pages from compressed cache on an LRU basis to the backing swap
device when the compressed pool reaches its size limit. This requirement had
been identified in prior community discussions.
Zswap is disabled by default but can be enabled at boot time by setting
the ``enabled`` attribute to 1 at boot time. ie: ``zswap.enabled=1``. Zswap
can also be enabled and disabled at runtime using the sysfs interface.
Whether Zswap is enabled at the boot time depends on whether
the ``CONFIG_ZSWAP_DEFAULT_ON`` Kconfig option is enabled or not.
This setting can then be overridden by providing the kernel command line
``zswap.enabled=`` option, for example ``zswap.enabled=0``.
Zswap can also be enabled and disabled at runtime using the sysfs interface.
An example command to enable zswap at runtime, assuming sysfs is mounted
at ``/sys``, is::
@@ -64,9 +66,10 @@ allocation in zpool is not directly accessible by address. Rather, a handle is
returned by the allocation routine and that handle must be mapped before being
accessed. The compressed memory pool grows on demand and shrinks as compressed
pages are freed. The pool is not preallocated. By default, a zpool
of type zbud is created, but it can be selected at boot time by
setting the ``zpool`` attribute, e.g. ``zswap.zpool=zbud``. It can
also be changed at runtime using the sysfs ``zpool`` attribute, e.g.::
of type selected in ``CONFIG_ZSWAP_ZPOOL_DEFAULT`` Kconfig option is created,
but it can be overridden at boot time by setting the ``zpool`` attribute,
e.g. ``zswap.zpool=zbud``. It can also be changed at runtime using the sysfs
``zpool`` attribute, e.g.::
echo zbud > /sys/module/zswap/parameters/zpool
@@ -97,8 +100,9 @@ controlled policy:
* max_pool_percent - The maximum percentage of memory that the compressed
pool can occupy.
The default compressor is lzo, but it can be selected at boot time by
setting the ``compressor`` attribute, e.g. ``zswap.compressor=lzo``.
The default compressor is selected in ``CONFIG_ZSWAP_COMPRESSOR_DEFAULT``
Kconfig option, but it can be overridden at boot time by setting the
``compressor`` attribute, e.g. ``zswap.compressor=lzo``.
It can also be changed at runtime using the sysfs "compressor"
attribute, e.g.::