zram: remove max_comp_streams device attr

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.o

zram: remove max_comp_streams device attr

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/[email protected]
Signed-off-by: Sergey Senozhatsky <[email protected]>
Cc: Hillf Danton <[email protected]>
Cc: Kairui Song <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Yosry Ahmed <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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Documentation: zram: fix dictionary spelling

Fixes a typo in the ZRAM documentation where 'dictioary' was
misspelled. Corrected it to 'dictionary' in the example usage
of 'algorithm_params'.

Signed

Documentation: zram: fix dictionary spelling

Fixes a typo in the ZRAM documentation where 'dictioary' was
misspelled. Corrected it to 'dictionary' in the example usage
of 'algorithm_params'.

Signed-off-by: Sarveshwaar SS <[email protected]>
Reviewed-by: Sergey Senozhatsky <[email protected]>
Signed-off-by: Jonathan Corbet <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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zram: permit only one post-processing operation at a time

Both recompress and writeback soon will unlock slots during processing,
which makes things too complex wrt possible race-conditions. We sti

zram: permit only one post-processing operation at a time

Both recompress and writeback soon will unlock slots during processing,
which makes things too complex wrt possible race-conditions. We still
want to clear PP_SLOT in slot_free, because this is how we figure out that
slot that was selected for post-processing has been released under us and
when we start post-processing we check if slot still has PP_SLOT set. At
the same time, theoretically, we can have something like this:

CPU0 CPU1

recompress
scan slots
set PP_SLOT
unlock slot
slot_free
clear PP_SLOT

allocate PP_SLOT
writeback
scan slots
set PP_SLOT
unlock slot
select PP-slot
test PP_SLOT

So recompress will not detect that slot has been re-used and re-selected
for concurrent writeback post-processing.

Make sure that we only permit on post-processing operation at a time. So
now recompress and writeback post-processing don't race against each
other, we only need to handle slot re-use (slot_free and write), which is
handled individually by each pp operation.

Having recompress and writeback competing for the same slots is not
exactly good anyway (can't imagine anyone doing that).

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Sergey Senozhatsky <[email protected]>
Cc: Minchan Kim <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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zram: support priority parameter in recompression

recompress device attribute supports alg=NAME parameter so that we can
specify only one particular algorithm we want to perform recompression
with.

zram: support priority parameter in recompression

recompress device attribute supports alg=NAME parameter so that we can
specify only one particular algorithm we want to perform recompression
with. However, with algo params we now can have several exactly same
secondary algorithms but each with its own params tuning (e.g. priority 1
configured to use more aggressive level, and priority 2 configured to use
a pre-trained dictionary). Support priority=NUM parameter so that we can
correctly determine which secondary algorithm we want to use.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Sergey Senozhatsky <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Nick Terrell <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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Documentation/zram: add documentation for algorithm parameters

Document brief description of compression algorithms' parameters:
compression level and pre-trained dictionary.

[senozhatsky@chromium.

Documentation/zram: add documentation for algorithm parameters

Document brief description of compression algorithms' parameters:
compression level and pre-trained dictionary.

[[email protected]: trivial fixup]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Sergey Senozhatsky <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Nick Terrell <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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zram: introduce algorithm_params device attribute

This attribute is used to setup compression algorithms' parameters, so we
can tweak algorithms' characteristics. At this point only 'level' is
supp

zram: introduce algorithm_params device attribute

This attribute is used to setup compression algorithms' parameters, so we
can tweak algorithms' characteristics. At this point only 'level' is
supported (to be extended in the future).

Each call sets up parameters for one particular algorithm, which should be
specified either by the algorithm's priority or algo name. This is
expected to be called after corresponding algorithm is selected via
comp_algorithm or recomp_algorithm.

echo "priority=0 level=1" > /sys/block/zram0/algorithm_params
or
echo "algo=zstd level=1" > /sys/block/zram0/algorithm_params

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Sergey Senozhatsky <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Nick Terrell <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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zram: introduce custom comp backends API

Moving to custom backends implementation gives us ability to have our own
minimalistic and extendable API, and algorithms tunings becomes possible.

The list

zram: introduce custom comp backends API

Moving to custom backends implementation gives us ability to have our own
minimalistic and extendable API, and algorithms tunings becomes possible.

The list of compression backends is empty at this point, we will add
backends in the followup patches.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Sergey Senozhatsky <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Nick Terrell <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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zram: add max_pages param to recompression

Introduce "max_pages" param to recompress device attribute which sets an
upper limit on the number of entries (pages) zram attempts to recompress
(in this

zram: add max_pages param to recompression

Introduce "max_pages" param to recompress device attribute which sets an
upper limit on the number of entries (pages) zram attempts to recompress
(in this particular recompression call). S/W recompression can be quite
expensive so limiting the number of pages recompress touches can be quite
helpful.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Sergey Senozhatsky <[email protected]>
Acked-by: Brian Geffon <[email protected]>
Cc: Minchan Kim <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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zram: split memory-tracking and ac-time tracking

ZRAM_MEMORY_TRACKING enables two features:
- per-entry ac-time tracking
- debugfs interface

The latter one is the reason why memory-tracking depends

zram: split memory-tracking and ac-time tracking

ZRAM_MEMORY_TRACKING enables two features:
- per-entry ac-time tracking
- debugfs interface

The latter one is the reason why memory-tracking depends on DEBUG_FS,
while the former one is used far beyond debugging these days. Namely
ac-time is used for fine grained writeback of idle entries (pages).

Move ac-time tracking under its own config option so that it can be
enabled (along with writeback) on systems without DEBUG_FS.

[[email protected]: ifdef fixup, per Dmytro]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Sergey Senozhatsky <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Dmytro Maluka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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zram: add incompressible flag to read_block_state()

Add a new flag to zram block state that shows if the page is
incompressible: that none of the algorithm (including secondary ones)
could compress

zram: add incompressible flag to read_block_state()

Add a new flag to zram block state that shows if the page is
incompressible: that none of the algorithm (including secondary ones)
could compress it.

Link: https://lkml.kernel.org/r/[email protected]
Suggested-by: Minchan Kim <[email protected]>
Signed-off-by: Sergey Senozhatsky <[email protected]>
Acked-by: Minchan Kim <[email protected]>
Cc: Alexey Romanov <[email protected]>
Cc: Nhat Pham <[email protected]>
Cc: Nitin Gupta <[email protected]>
Cc: Suleiman Souhlal <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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zram: add incompressible writeback

Add support for incompressible pages writeback:

echo incompressible > /sys/block/zramX/writeback

Link: https://lkml.kernel.org/r/20221109115047.2921851-13-seno

zram: add incompressible writeback

Add support for incompressible pages writeback:

echo incompressible > /sys/block/zramX/writeback

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Sergey Senozhatsky <[email protected]>
Acked-by: Minchan Kim <[email protected]>
Cc: Alexey Romanov <[email protected]>
Cc: Nhat Pham <[email protected]>
Cc: Nitin Gupta <[email protected]>
Cc: Suleiman Souhlal <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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documentation: add zram recompression documentation

Document user-space visible device attributes that are enabled by
ZRAM_MULTI_COMP.

Link: https://lkml.kernel.org/r/20221109115047.2921851-12-seno

documentation: add zram recompression documentation

Document user-space visible device attributes that are enabled by
ZRAM_MULTI_COMP.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Sergey Senozhatsky <[email protected]>
Acked-by: Minchan Kim <[email protected]>
Cc: Alexey Romanov <[email protected]>
Cc: Nhat Pham <[email protected]>
Cc: Nitin Gupta <[email protected]>
Cc: Suleiman Souhlal <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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zram: add recompress flag to read_block_state()

Add a new flag to zram block state that shows if the page was recompressed
(using alternative compression algorithm).

Link: https://lkml.kernel.org/r

zram: add recompress flag to read_block_state()

Add a new flag to zram block state that shows if the page was recompressed
(using alternative compression algorithm).

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Sergey Senozhatsky <[email protected]>
Acked-by: Minchan Kim <[email protected]>
Cc: Alexey Romanov <[email protected]>
Cc: Nhat Pham <[email protected]>
Cc: Nitin Gupta <[email protected]>
Cc: Suleiman Souhlal <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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zram: add a huge_idle writeback mode

Today it's only possible to write back as a page, idle, or huge. A user
might want to writeback pages which are huge and idle first as these idle
pages do not r

zram: add a huge_idle writeback mode

Today it's only possible to write back as a page, idle, or huge. A user
might want to writeback pages which are huge and idle first as these idle
pages do not require decompression and make a good first pass for
writeback.

Idle writeback specifically has the advantage that a refault is unlikely
given that the page has been swapped for some amount of time without being
refaulted.

Huge writeback has the advantage that you're guaranteed to get the maximum
benefit from a single page writeback, that is, you're reclaiming one full
page of memory. Pages which are compressed in zram being written back
result in some benefit which is always less than a page size because of
the fact that it was compressed.

The primary use of this is for minimizing refaults in situations where the
device has to be sensitive to storage endurance. On ChromeOS we have
devices with slow eMMC and repeated writes and refaults can negatively
affect performance and endurance.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Brian Geffon <[email protected]>
Acked-by: Minchan Kim <[email protected]>
Cc: Nitin Gupta <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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docs: Fix wording in optional zram feature docs

This fixes some simple grammar errors in the documentation for zram,
specifically errors in the optional feature section of the zram
documentation.

S

docs: Fix wording in optional zram feature docs

This fixes some simple grammar errors in the documentation for zram,
specifically errors in the optional feature section of the zram
documentation.

Signed-off-by: Ethan Dye <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jonathan Corbet <[email protected]>

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zram: introduce an aged idle interface

This change introduces an aged idle interface to the existing idle sysfs
file for zram.

When CONFIG_ZRAM_MEMORY_TRACKING is enabled the idle file now also
acc

zram: introduce an aged idle interface

This change introduces an aged idle interface to the existing idle sysfs
file for zram.

When CONFIG_ZRAM_MEMORY_TRACKING is enabled the idle file now also
accepts an integer argument. This integer is the age (in seconds) of
pages to mark as idle. The idle file still supports 'all' as it always
has. This new approach allows for much more control over which pages
get marked as idle.

[[email protected]: use IS_ENABLED and cleanup comment]
Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: Sergey's cleanup suggestions]
Link: https://lkml.kernel.org/r/[email protected]

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Brian Geffon <[email protected]>
Acked-by: Minchan Kim <[email protected]>
Reviewed-by: Sergey Senozhatsky <[email protected]>
Cc: Nitin Gupta <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Suleiman Souhlal <[email protected]>
Cc: Jesse Barnes <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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zram: add stat to gather incompressible pages since zram set up

Currently, zram supports the stat via /sys/block/zram/mm_stat to represent
how many of incompressible pages are stored at the moment b

zram: add stat to gather incompressible pages since zram set up

Currently, zram supports the stat via /sys/block/zram/mm_stat to represent
how many of incompressible pages are stored at the moment but it couldn't
show how many times incompressible pages were wrote down since zram set
up. It's also good indication to see how zram is effective in the system.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Minchan Kim <[email protected]>
Reviewed-by: Sergey Senozhatsky <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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zram: support page writeback

There is demand to writeback specific process pages to backing store
instead of all idles pages in the system due to storage wear out concerns
and to launching latency o

zram: support page writeback

There is demand to writeback specific process pages to backing store
instead of all idles pages in the system due to storage wear out concerns
and to launching latency of apps which are most of the time idle but are
critical for resume latency.

This patch extends the writeback knob to support a specific page
writeback.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Minchan Kim <[email protected]>
Reviewed-by: Sergey Senozhatsky <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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Documentation: fix typos found in admin-guide subdirectory

Fixed twelve typos in cppc_sysfs.rst, binderfs.rst, paride.rst,
zram.rst, bug-hunting.rst, introduction.rst, usage.rst, dm-crypt.rst

Signe

Documentation: fix typos found in admin-guide subdirectory

Fixed twelve typos in cppc_sysfs.rst, binderfs.rst, paride.rst,
zram.rst, bug-hunting.rst, introduction.rst, usage.rst, dm-crypt.rst

Signed-off-by: Andrew Klychkov <[email protected]>
Reviewed-by: Jonathan Corbet <[email protected]>
Reviewed-by: Randy Dunlap <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jonathan Corbet <[email protected]>

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Documentation: zram: fix the description about orig_data_size of mm_stat

orig_data_size counted the same_pages by commit 51f9f82c855d ("zram:
count same page write as page_stored"), so let's fix it.

Documentation: zram: fix the description about orig_data_size of mm_stat

orig_data_size counted the same_pages by commit 51f9f82c855d ("zram:
count same page write as page_stored"), so let's fix it.

Signed-off-by: Yue Hu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jonathan Corbet <[email protected]>

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zram: correct documentation about sysfs node of huge page writeback

sysfs node for huge page writeback is writeback rather than write.

Signed-off-by: Yue Hu <[email protected]>
Acked-by: Minchan Ki

zram: correct documentation about sysfs node of huge page writeback

sysfs node for huge page writeback is writeback rather than write.

Signed-off-by: Yue Hu <[email protected]>
Acked-by: Minchan Kim <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jonathan Corbet <[email protected]>

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Documentation: zram: various fixes in zram.rst

Fix various items in zram.rst:
- typos/spellos
- punctuation
- grammar
- shell syntax
- indentation
- sysfs file names

Signed-off-by: Randy Dunlap <rd

Documentation: zram: various fixes in zram.rst

Fix various items in zram.rst:
- typos/spellos
- punctuation
- grammar
- shell syntax
- indentation
- sysfs file names

Signed-off-by: Randy Dunlap <[email protected]>
Acked-by: Minchan Kim <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jonathan Corbet <[email protected]>

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docs: blockdev: add it to the admin-guide

The blockdev book basically contains user-faced documentation.

Signed-off-by: Mauro Carvalho Chehab <[email protected]>