Follow the steps: https://github.com/facebook/zstd/blob/v1.5.7/contrib/linux-kernel/README.md
The following committed changes are also preserved:
70168143b302378ccff178bf28cb140c783dac88 zstd: merge optimization from Samsung <DevriesL>
0b893588096921a258f8ca27d6005da4201c9b58 lib: zstd: Don't inline functions in zstd_opt.c <Nick Terrell>
Signed-off-by: Sorayukii <sorayukii69@gmail.com>
Pzqqtauthored and Sorayukiicommited 2026-05-15 18:07:07 +07:00
Follow the steps: https://github.com/facebook/zstd/blob/v1.5.6/contrib/linux-kernel/README.md
The following committed changes are also preserved:
c97320470b510a90bac077842630bd49c7cce95e zstd: merge optimization from Samsung <DevriesL>
9df1909b60b40fc7450ebff9b45d7cd2ac70225d lib: zstd: Don't inline functions in zstd_opt.c <Nick Terrell>
Signed-off-by: Sorayukii <sorayukii69@gmail.com>
Pzqqtauthored and Sorayukiicommited 2026-05-15 18:07:07 +07:00
- ZSTD_resetDstream() is deprecated hence it is wise to make zstd_reset_dstream() functionally identical to ZSTD_resetDstream() as we have done for the compression stream in [1].
- Also make ZSTD_startingInputLength() visible for the decompression driver to be able to use it.
- This fixes the below warning:
../lib/zstd/zstd_decompress_module.c: In function 'zstd_reset_dstream':
../lib/zstd/zstd_decompress_module.c:80:9: warning: 'ZSTD_resetDStream' is deprecated [-Wdeprecated-declarations]
80 | return ZSTD_resetDStream(dstream);
| ^~~~~~
In file included from ../include/linux/zstd.h:26,
from ../lib/zstd/zstd_decompress_module.c:15:
../include/linux/zstd_lib.h:2569:27: note: declared here
2569 | ZSTDLIB_STATIC_API size_t ZSTD_resetDStream(ZSTD_DStream* zds);
| ^~~~~~~~~~~~~~~~~
[1]: https://github.com/facebook/zstd/pull/3088
Signed-off-by: Cyber Knight <cyberknight755@gmail.com>
Signed-off-by: Sorayukii <sorayukii69@gmail.com>
Cyber Knightauthored and Sorayukiicommited 2026-05-15 18:07:07 +07:00
ld.lld: error: duplicate symbol: ZSTD_isError
>>> defined at error_private.h:47 (../../../../../../src/kernel/xiaomi/rova/lib/zstd/common/error_private.h:47)
>>> lib/zstd/zstd_compress.o:(ZSTD_isError)
>>> defined at error_private.h:47 (../../../../../../src/kernel/xiaomi/rova/lib/zstd/common/error_private.h:47)
>>> lib/zstd/zstd_decompress.o:(.text+0x2570)
and many more...
Signed-off-by: iusmac <iusico.maxim@libero.it>
Signed-off-by: Sorayukii <sorayukii69@gmail.com>
iusmacauthored and Sorayukiicommited 2026-05-15 18:07:06 +07:00
CC lib/zstd/compress/zstd_compress_sequences.o
In file included from ../../../../../../src/kernel/xiaomi/rova/lib/zstd/compress/zstd_compress_sequences.c:14:
In file included from ../../../../../../src/kernel/xiaomi/rova/lib/zstd/compress/zstd_compress_sequences.h:14:
../../../../../../src/kernel/xiaomi/rova/lib/zstd/compress/../common/fse.h:64:16: error: unknown type name 'size_t'
FSE_PUBLIC_API size_t FSE_compress(void* dst, size_t dstCapacity,
^
Signed-off-by: iusmac <iusico.maxim@libero.it>
Signed-off-by: Sorayukii <sorayukii69@gmail.com>
iusmacauthored and Sorayukiicommited 2026-05-15 18:07:06 +07:00
After the update to zstd-1.4.10 passing -O3 is no longer necessary to
get good performance from zstd. Using the default optimization level -O2
is sufficient to get good performance.
I've measured no significant change to compression speed, and a ~1%
decompression speed loss, which is acceptable.
This fixes the reported parisc -Wframe-larger-than=1536 errors [0]. The
gcc-8-hppa-linux-gnu compiler performed very poorly with -O3, generating
stacks that are ~3KB. With -O2 these same functions generate stacks in
the < 100B, completely fixing the problem. Function size deltas are
listed below:
ZSTD_compressBlock_fast_extDict_generic: 3800 -> 68
ZSTD_compressBlock_fast: 2216 -> 40
ZSTD_compressBlock_fast_dictMatchState: 1848 -> 64
ZSTD_compressBlock_doubleFast_extDict_generic: 3744 -> 76
ZSTD_fillDoubleHashTable: 3252 -> 0
ZSTD_compressBlock_doubleFast: 5856 -> 36
ZSTD_compressBlock_doubleFast_dictMatchState: 5380 -> 84
ZSTD_copmressBlock_lazy2: 2420 -> 72
Additionally, this improves the reported code bloat [1]. With gcc-11
bloat-o-meter shows an 80KB code size improvement:
```
> ../scripts/bloat-o-meter vmlinux.old vmlinux
add/remove: 31/8 grow/shrink: 24/155 up/down: 25734/-107924 (-82190)
Total: Before=6418562, After=6336372, chg -1.28%
```
Compared to before the zstd-1.4.10 update we see a total code size
regression of 105KB, down from 374KB at v5.16-rc1:
```
> ../scripts/bloat-o-meter vmlinux.old vmlinux
add/remove: 292/62 grow/shrink: 56/88 up/down: 235009/-127487 (107522)
Total: Before=6228850, After=6336372, chg +1.73%
```
[0] https://lkml.org/lkml/2021/11/15/710
[1] https://lkml.org/lkml/2021/11/14/189
Link: https://lore.kernel.org/r/20211117014949.1169186-4-nickrterrell@gmail.com/
Link: https://lore.kernel.org/r/20211117201459.1194876-4-nickrterrell@gmail.com/
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Nick Terrell <terrelln@fb.com>
Signed-off-by: Sorayukii <sorayukii69@gmail.com>
Nick Terrellauthored and Sorayukiicommited 2026-05-15 18:07:06 +07:00
`zstd_opt.c` contains the match finder for the highest compression
levels. These levels are already very slow, and are unlikely to be used
in the kernel. If they are used, they shouldn't be used in latency
sensitive workloads, so slowing them down shouldn't be a big deal.
This saves 188 KB of the 288 KB regression reported by Geert Uytterhoeven [0].
I've also opened an issue upstream [1] so that we can properly tackle
the code size issue in `zstd_opt.c` for all users, and can hopefully
remove this hack in the next zstd version we import.
Bloat-o-meter output on x86-64:
```
> ../scripts/bloat-o-meter vmlinux.old vmlinux
add/remove: 6/5 grow/shrink: 1/9 up/down: 16673/-209939 (-193266)
Function old new delta
ZSTD_compressBlock_opt_generic.constprop - 7559 +7559
ZSTD_insertBtAndGetAllMatches - 6304 +6304
ZSTD_insertBt1 - 1731 +1731
ZSTD_storeSeq - 693 +693
ZSTD_BtGetAllMatches - 255 +255
ZSTD_updateRep - 128 +128
ZSTD_updateTree 96 99 +3
ZSTD_insertAndFindFirstIndexHash3 81 - -81
ZSTD_setBasePrices.constprop 98 - -98
ZSTD_litLengthPrice.constprop 138 - -138
ZSTD_count 362 181 -181
ZSTD_count_2segments 1407 938 -469
ZSTD_insertBt1.constprop 2689 - -2689
ZSTD_compressBlock_btultra2 19990 423 -19567
ZSTD_compressBlock_btultra 19633 15 -19618
ZSTD_initStats_ultra 19825 - -19825
ZSTD_compressBlock_btopt 20374 12 -20362
ZSTD_compressBlock_btopt_extDict 29984 12 -29972
ZSTD_compressBlock_btultra_extDict 30718 15 -30703
ZSTD_compressBlock_btopt_dictMatchState 32689 12 -32677
ZSTD_compressBlock_btultra_dictMatchState 33574 15 -33559
Total: Before=6611828, After=6418562, chg -2.92%
```
[0] https://lkml.org/lkml/2021/11/14/189
[1] https://github.com/facebook/zstd/issues/2862
Link: https://lore.kernel.org/r/20211117014949.1169186-3-nickrterrell@gmail.com/
Link: https://lore.kernel.org/r/20211117201459.1194876-3-nickrterrell@gmail.com/
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Nick Terrell <terrelln@fb.com>
Signed-off-by: Sorayukii <sorayukii69@gmail.com>
Nick Terrellauthored and Sorayukiicommited 2026-05-15 18:07:06 +07:00
The variable `litLengthSum` is only used by an `assert()`, so when
asserts are disabled the compiler doesn't see any usage and warns.
This issue is already fixed upstream by PR #2838 [0]. It was reported
by the Kernel test robot in [1].
Another approach would be to change zstd's disabled `assert()`
definition to use the argument in a disabled branch, instead of
ignoring the argument. I've avoided this approach because there are
some small changes necessary to get zstd to build, and I would
want to thoroughly re-test for performance, since that is slightly
changing the code in every function in zstd. It seems like a
trivial change, but some functions are pretty sensitive to small
changes. However, I think it is a valid approach that I would
like to see upstream take, so I've opened Issue #2868 to attempt
this upstream.
Lastly, I've chosen not to use __maybe_unused because all code
in lib/zstd/ must eventually be upstreamed. Upstream zstd can't
use __maybe_unused because it isn't portable across all compilers.
[0] https://github.com/facebook/zstd/pull/2838
[1] https://lore.kernel.org/linux-mm/202111120312.833wII4i-lkp@intel.com/T/
[2] https://github.com/facebook/zstd/issues/2868
Link: https://lore.kernel.org/r/20211117014949.1169186-2-nickrterrell@gmail.com/
Link: https://lore.kernel.org/r/20211117201459.1194876-2-nickrterrell@gmail.com/
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Nick Terrell <terrelln@fb.com>
Signed-off-by: Sorayukii <sorayukii69@gmail.com>
Nick Terrellauthored and Sorayukiicommited 2026-05-15 18:07:06 +07:00
A new warning in clang warns that there is an instance where boolean
expressions are being used with bitwise operators instead of logical
ones:
lib/zstd/decompress/huf_decompress.c:890:25: warning: use of bitwise '&' with boolean operands [-Wbitwise-instead-of-logical]
(BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished)
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
zstd does this frequently to help with performance, as logical operators
have branches whereas bitwise ones do not.
To fix this warning in other cases, the expressions were placed on
separate lines with the '&=' operator; however, this particular instance
was moved away from that so that it could be surrounded by LIKELY, which
is a macro for __builtin_expect(), to help with a performance
regression, according to upstream zstd pull #1973.
Aside from switching to logical operators, which is likely undesirable
in this instance, or disabling the warning outright, the solution is
casting one of the expressions to an integer type to make it clear to
clang that the author knows what they are doing. Add a cast to U32 to
silence the warning. The first U32 cast is to silence an instance of
-Wshorten-64-to-32 because __builtin_expect() returns long so it cannot
be moved.
Link: https://github.com/ClangBuiltLinux/linux/issues/1486
Link: https://github.com/facebook/zstd/pull/1973
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Nick Terrell <terrelln@fb.com>
Signed-off-by: Sorayukii <sorayukii69@gmail.com>
Nathan Chancellorauthored and Sorayukiicommited 2026-05-15 18:07:05 +07:00
Upgrade to the latest upstream zstd version 1.4.10.
This patch is 100% generated from upstream zstd commit 20821a46f412 [0].
This patch is very large because it is transitioning from the custom
kernel zstd to using upstream directly. The new zstd follows upstreams
file structure which is different. Future update patches will be much
smaller because they will only contain the changes from one upstream
zstd release.
As an aid for review I've created a commit [1] that shows the diff
between upstream zstd as-is (which doesn't compile), and the zstd
code imported in this patch. The verion of zstd in this patch is
generated from upstream with changes applied by automation to replace
upstreams libc dependencies, remove unnecessary portability macros,
replace `/**` comments with `/*` comments, and use the kernel's xxhash
instead of bundling it.
The benefits of this patch are as follows:
1. Using upstream directly with automated script to generate kernel
code. This allows us to update the kernel every upstream release, so
the kernel gets the latest bug fixes and performance improvements,
and doesn't get 3 years out of date again. The automation and the
translated code are tested every upstream commit to ensure it
continues to work.
2. Upgrades from a custom zstd based on 1.3.1 to 1.4.10, getting 3 years
of performance improvements and bug fixes. On x86_64 I've measured
15% faster BtrFS and SquashFS decompression+read speeds, 35% faster
kernel decompression, and 30% faster ZRAM decompression+read speeds.
3. Zstd-1.4.10 supports negative compression levels, which allow zstd to
match or subsume lzo's performance.
4. Maintains the same kernel-specific wrapper API, so no callers have to
be modified with zstd version updates.
One concern that was brought up was stack usage. Upstream zstd had
already removed most of its heavy stack usage functions, but I just
removed the last functions that allocate arrays on the stack. I've
measured the high water mark for both compression and decompression
before and after this patch. Decompression is approximately neutral,
using about 1.2KB of stack space. Compression levels up to 3 regressed
from 1.4KB -> 1.6KB, and higher compression levels regressed from 1.5KB
-> 2KB. We've added unit tests upstream to prevent further regression.
I believe that this is a reasonable increase, and if it does end up
causing problems, this commit can be cleanly reverted, because it only
touches zstd.
I chose the bulk update instead of replaying upstream commits because
there have been ~3500 upstream commits since the 1.3.1 release, zstd
wasn't ready to be used in the kernel as-is before a month ago, and not
all upstream zstd commits build. The bulk update preserves bisectablity
because bugs can be bisected to the zstd version update. At that point
the update can be reverted, and we can work with upstream to find and
fix the bug.
Note that upstream zstd release 1.4.10 doesn't exist yet. I have cut a
staging branch at 20821a46f412 [0] and will apply any changes requested
to the staging branch. Once we're ready to merge this update I will cut
a zstd release at the commit we merge, so we have a known zstd release
in the kernel.
The implementation of the kernel API is contained in
zstd_compress_module.c and zstd_decompress_module.c.
[0] 20821a46f4
[1] e0fa481d0e
Signed-off-by: Nick Terrell <terrelln@fb.com>
Tested By: Paul Jones <paul@pauljones.id.au>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang v13.0.0 on x86-64
Tested-by: Jean-Denis Girard <jd.girard@sysnux.pf>
Signed-off-by: Sorayukii <sorayukii69@gmail.com>
Nick Terrellauthored and Sorayukiicommited 2026-05-15 18:07:05 +07:00
This patch:
- Moves `include/linux/zstd.h` -> `include/linux/zstd_lib.h`
- Updates modified zstd headers to yearless copyright
- Adds a new API in `include/linux/zstd.h` that is functionally
equivalent to the in-use subset of the current API. Functions are
renamed to avoid symbol collisions with zstd, to make it clear it is
not the upstream zstd API, and to follow the kernel style guide.
- Updates all callers to use the new API.
There are no functional changes in this patch. Since there are no
functional change, I felt it was okay to update all the callers in a
single patch. Once the API is approved, the callers are mechanically
changed.
This patch is preparing for the 3rd patch in this series, which updates
zstd to version 1.4.10. Since the upstream zstd API is no longer exposed
to callers, the update can happen transparently.
Signed-off-by: Nick Terrell <terrelln@fb.com>
Tested By: Paul Jones <paul@pauljones.id.au>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang v13.0.0 on x86-64
Tested-by: Jean-Denis Girard <jd.girard@sysnux.pf>
Signed-off-by: Sorayukii <sorayukii69@gmail.com>
Nick Terrellauthored and Sorayukiicommited 2026-05-15 18:07:05 +07:00
Add zstd compression and decompression kernel modules.
zstd offers a wide varity of compression speed and quality trade-offs.
It can compress at speeds approaching lz4, and quality approaching lzma.
zstd decompressions at speeds more than twice as fast as zlib, and
decompression speed remains roughly the same across all compression levels.
The code was ported from the upstream zstd source repository. The
`linux/zstd.h` header was modified to match linux kernel style.
The cross-platform and allocation code was stripped out. Instead zstd
requires the caller to pass a preallocated workspace. The source files
were clang-formatted [1] to match the Linux Kernel style as much as
possible. Otherwise, the code was unmodified. We would like to avoid
as much further manual modification to the source code as possible, so it
will be easier to keep the kernel zstd up to date.
I benchmarked zstd compression as a special character device. I ran zstd
and zlib compression at several levels, as well as performing no
compression, which measure the time spent copying the data to kernel space.
Data is passed to the compresser 4096 B at a time. The benchmark file is
located in the upstream zstd source repository under
`contrib/linux-kernel/zstd_compress_test.c` [2].
I ran the benchmarks on a Ubuntu 14.04 VM with 2 cores and 4 GiB of RAM.
The VM is running on a MacBook Pro with a 3.1 GHz Intel Core i7 processor,
16 GB of RAM, and a SSD. I benchmarked using `silesia.tar` [3], which is
211,988,480 B large. Run the following commands for the benchmark:
sudo modprobe zstd_compress_test
sudo mknod zstd_compress_test c 245 0
sudo cp silesia.tar zstd_compress_test
The time is reported by the time of the userland `cp`.
The MB/s is computed with
1,536,217,008 B / time(buffer size, hash)
which includes the time to copy from userland.
The Adjusted MB/s is computed with
1,536,217,088 B / (time(buffer size, hash) - time(buffer size, none)).
The memory reported is the amount of memory the compressor requests.
| Method | Size (B) | Time (s) | Ratio | MB/s | Adj MB/s | Mem (MB) |
|----------|----------|----------|-------|---------|----------|----------|
| none | 11988480 | 0.100 | 1 | 2119.88 | - | - |
| zstd -1 | 73645762 | 1.044 | 2.878 | 203.05 | 224.56 | 1.23 |
| zstd -3 | 66988878 | 1.761 | 3.165 | 120.38 | 127.63 | 2.47 |
| zstd -5 | 65001259 | 2.563 | 3.261 | 82.71 | 86.07 | 2.86 |
| zstd -10 | 60165346 | 13.242 | 3.523 | 16.01 | 16.13 | 13.22 |
| zstd -15 | 58009756 | 47.601 | 3.654 | 4.45 | 4.46 | 21.61 |
| zstd -19 | 54014593 | 102.835 | 3.925 | 2.06 | 2.06 | 60.15 |
| zlib -1 | 77260026 | 2.895 | 2.744 | 73.23 | 75.85 | 0.27 |
| zlib -3 | 72972206 | 4.116 | 2.905 | 51.50 | 52.79 | 0.27 |
| zlib -6 | 68190360 | 9.633 | 3.109 | 22.01 | 22.24 | 0.27 |
| zlib -9 | 67613382 | 22.554 | 3.135 | 9.40 | 9.44 | 0.27 |
I benchmarked zstd decompression using the same method on the same machine.
The benchmark file is located in the upstream zstd repo under
`contrib/linux-kernel/zstd_decompress_test.c` [4]. The memory reported is
the amount of memory required to decompress data compressed with the given
compression level. If you know the maximum size of your input, you can
reduce the memory usage of decompression irrespective of the compression
level.
| Method | Time (s) | MB/s | Adjusted MB/s | Memory (MB) |
|----------|----------|---------|---------------|-------------|
| none | 0.025 | 8479.54 | - | - |
| zstd -1 | 0.358 | 592.15 | 636.60 | 0.84 |
| zstd -3 | 0.396 | 535.32 | 571.40 | 1.46 |
| zstd -5 | 0.396 | 535.32 | 571.40 | 1.46 |
| zstd -10 | 0.374 | 566.81 | 607.42 | 2.51 |
| zstd -15 | 0.379 | 559.34 | 598.84 | 4.61 |
| zstd -19 | 0.412 | 514.54 | 547.77 | 8.80 |
| zlib -1 | 0.940 | 225.52 | 231.68 | 0.04 |
| zlib -3 | 0.883 | 240.08 | 247.07 | 0.04 |
| zlib -6 | 0.844 | 251.17 | 258.84 | 0.04 |
| zlib -9 | 0.837 | 253.27 | 287.64 | 0.04 |
Tested in userland using the test-suite in the zstd repo under
`contrib/linux-kernel/test/UserlandTest.cpp` [5] by mocking the kernel
functions. Fuzz tested using libfuzzer [6] with the fuzz harnesses under
`contrib/linux-kernel/test/{RoundTripCrash.c,DecompressCrash.c}` [7] [8]
with ASAN, UBSAN, and MSAN. Additionaly, it was tested while testing the
BtrFS and SquashFS patches coming next.
[1] https://clang.llvm.org/docs/ClangFormat.html
[2] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/zstd_compress_test.c
[3] http://sun.aei.polsl.pl/~sdeor/index.php?page=silesia
[4] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/zstd_decompress_test.c
[5] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/test/UserlandTest.cpp
[6] http://llvm.org/docs/LibFuzzer.html
[7] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/test/RoundTripCrash.c
[8] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/test/DecompressCrash.c
zstd source repository: https://github.com/facebook/zstd
Signed-off-by: Nick Terrell <terrelln@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
(cherry picked from commit 73f3d1b48f5069d46ba48aa28c2898dc93185560)
Signed-off-by: Peter Kalauskas <peskal@google.com>
Bug: 112488418
Change-Id: I6321071707a322683a4b35d047e7410c5a67acdc
Nick Terrellauthored and Peter Kalauskascommited 2018-08-23 12:05:06 -07:00
Pzqqt
authored and
Sorayukii
commited 
Cyber Knight
authored and
iusmac
authored and
tarsin
authored and
Nick Terrell
authored and
Nathan Chancellor
authored and
Peter Kalauskas
commited