> On Sep 29, 2020, at 11:53 PM, Nick Terrell <nickrterrell@xxxxxxxxx> wrote: > > From: Nick Terrell <terrelln@xxxxxx> It has been brought to my attention that patch 3 hasn’t made it to patchwork, likely because it is too large. I’ll include a pull request in the next cover letter, together with the patches (if needed). Please pull from git@xxxxxxxxxx:terrelln/linux.git tags/v4-zstd-1.4.6 to get these changes. > This patchset upgrades the zstd library to the latest upstream release. The > current zstd version in the kernel is a modified version of upstream zstd-1.3.1. > At the time it was integrated, zstd wasn't ready to be used in the kernel as-is. > But, it is now possible to use upstream zstd directly in the kernel. > > I have not yet release zstd-1.4.6 upstream. I want the zstd version in the kernel > to match up with a known upstream release, so we know exactly what code is > running. Whenever this patchset is ready for merge, I will cut a release at the > upstream commit that gets merged. This should not be necessary for future > releases. > > The kernel zstd library is automatically generated from upstream zstd. A script > makes the necessary changes and imports it into the kernel. The changes are: > > 1. Replace all libc dependencies with kernel replacements and rewrite includes. > 2. Remove unncessary portability macros like: #if defined(_MSC_VER). > 3. Use the kernel xxhash instead of bundling it. > > This automation gets tested every commit by upstream's continuous integration. > When we cut a new zstd release, we will submit a patch to the kernel to update > the zstd version in the kernel. > > I've updated zstd to upstream with one big patch because every commit must build, > so that precludes partial updates. Since the commit is 100% generated, I hope the > review burden is lightened. I considered replaying upstream commits, but that is > not possible because there have been ~3500 upstream commits since the last zstd > import, and the commits don't all build individually. 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. After this big switch in how the kernel consumes zstd, future patches > will be smaller, because they will only have one upstream release worth of > changes each. > > This patchset changes the zstd API from a custom kernel API to the upstream API. > I considered wrapping the upstream API with a wrapper that is closer to the > kernel style guide. Following advise from https://lkml.org/lkml/2020/9/17/814 > I've chosen to use the upstream API directly, to minimize opportunities to > introduce bugs, and because using the upstream API directly makes debugging and > communication with upstream easier. > > This patchset comes in 3 parts: > 1. The first 2 patches prepare for the zstd upgrade. The first patch adds a > compatibility wrapper so zstd can be upgraded without modifying any callers. > The second patch adds an indirection for the lib/decompress_unzstd.c including > of all decompression source files. > 2. Import zstd-1.4.6. This patch is completely generated from upstream using > automated tooling. > 3. Update all callers to the zstd-1.4.6 API then delete the compatibility > wrapper. > > I tested every caller of zstd on x86_64. I tested both after the 1.4.6 upgrade > using the compatibility wrapper, and after the final patch in this series. > > I tested kernel and initramfs decompression in i386 and arm. > > I ran benchmarks to compare the current zstd in the kernel with zstd-1.4.6. > I benchmarked on x86_64 using QEMU with KVM enabled on an Intel i9-9900k. > I found: > * BtrFS zstd compression at levels 1 and 3 is 5% faster > * BtrFS zstd decompression+read is 15% faster > * SquashFS zstd decompression+read is 15% faster > * F2FS zstd compression+write at level 3 is 8% faster > * F2FS zstd decompression+read is 20% faster > * ZRAM decompression+read is 30% faster > * Kernel zstd decompression is 35% faster > * Initramfs zstd decompression+build is 5% faster > > The latest zstd also offers bug fixes and a 1 KB reduction in stack uage during > compression. For example the recent problem with large kernel decompression has > been fixed upstream for over 2 years https://lkml.org/lkml/2020/9/29/27. > > Please let me know if there is anything that I can do to ease the way for these > patches. I think it is important because it gets large performance improvements, > contains bug fixes, and is switching to a more maintainable model of consuming > upstream zstd directly, making it easy to keep up to date. > > Best, > Nick Terrell > > v1 -> v2: > * Successfully tested F2FS with help from Chao Yu to fix my test. > * (1/9) Fix ZSTD_initCStream() wrapper to handle pledged_src_size=0 means unknown. > This fixes F2FS with the zstd-1.4.6 compatibility wrapper, exposed by the test. > > v2 -> v3: > * (3/9) Silence warnings by Kernel Test Robot: > https://github.com/facebook/zstd/pull/2324 > Stack size warnings remain, but these aren't new, and the functions it warns on > are either unused or not in the maximum stack path. This patchset reduces zstd > compression stack usage by 1 KB overall. I've gotten the low hanging fruit, and > more stack reduction would require significant changes that have the potential > to introduce new bugs. However, I do hope to continue to reduce zstd stack > usage in future versions. > > v3 -> v4: > * (3/9) Fix errors and warnings reported by Kernel Test Robot: > https://github.com/facebook/zstd/pull/2326 > - Replace mem.h with a custom kernel implementation that matches the current > lib/zstd/mem.h in the kernel. This avoids calls to __builtin_bswap*() which > don't work on certain architectures, as exposed by the Kernel Test Robot. > - Remove ASAN/MSAN (un)poisoning code which doesn't work in the kernel, as > exposed by the Kernel Test Robot. > - I've fixed all of the valid cppcheck warnings reported, but there were many > false positives, where cppcheck was incorrectly analyzing the situation, > which I did not fix. I don't believe it is reasonable to expect that upstream > zstd silences all the static analyzer false positives. Upstream zstd uses > clang scan-build for its static analysis. We find that supporting multiple > static analysis tools multiplies the burden of silencing false positives, > without providing enough marginal value over running a single static analysis > tool. > > Nick Terrell (9): > lib: zstd: Add zstd compatibility wrapper > lib: zstd: Add decompress_sources.h for decompress_unzstd > lib: zstd: Upgrade to latest upstream zstd version 1.4.6 > crypto: zstd: Switch to zstd-1.4.6 API > btrfs: zstd: Switch to the zstd-1.4.6 API > f2fs: zstd: Switch to the zstd-1.4.6 API > squashfs: zstd: Switch to the zstd-1.4.6 API > lib: unzstd: Switch to the zstd-1.4.6 API > lib: zstd: Remove zstd compatibility wrapper > > crypto/zstd.c | 22 +- > fs/btrfs/zstd.c | 46 +- > fs/f2fs/compress.c | 100 +- > fs/squashfs/zstd_wrapper.c | 7 +- > include/linux/zstd.h | 3021 ++++++++---- > include/linux/zstd_errors.h | 76 + > lib/decompress_unzstd.c | 44 +- > lib/zstd/Makefile | 35 +- > lib/zstd/bitstream.h | 379 -- > lib/zstd/common/bitstream.h | 437 ++ > lib/zstd/common/compiler.h | 150 + > lib/zstd/common/cpu.h | 194 + > lib/zstd/common/debug.c | 24 + > lib/zstd/common/debug.h | 101 + > lib/zstd/common/entropy_common.c | 355 ++ > lib/zstd/common/error_private.c | 55 + > lib/zstd/common/error_private.h | 66 + > lib/zstd/common/fse.h | 709 +++ > lib/zstd/common/fse_decompress.c | 380 ++ > lib/zstd/common/huf.h | 352 ++ > lib/zstd/common/mem.h | 258 + > lib/zstd/common/zstd_common.c | 83 + > lib/zstd/common/zstd_deps.h | 124 + > lib/zstd/common/zstd_internal.h | 438 ++ > lib/zstd/compress.c | 3485 -------------- > lib/zstd/compress/fse_compress.c | 625 +++ > lib/zstd/compress/hist.c | 165 + > lib/zstd/compress/hist.h | 75 + > lib/zstd/compress/huf_compress.c | 764 +++ > lib/zstd/compress/zstd_compress.c | 4157 +++++++++++++++++ > lib/zstd/compress/zstd_compress_internal.h | 1103 +++++ > lib/zstd/compress/zstd_compress_literals.c | 158 + > lib/zstd/compress/zstd_compress_literals.h | 29 + > lib/zstd/compress/zstd_compress_sequences.c | 433 ++ > lib/zstd/compress/zstd_compress_sequences.h | 54 + > lib/zstd/compress/zstd_compress_superblock.c | 849 ++++ > lib/zstd/compress/zstd_compress_superblock.h | 32 + > lib/zstd/compress/zstd_cwksp.h | 465 ++ > lib/zstd/compress/zstd_double_fast.c | 521 +++ > lib/zstd/compress/zstd_double_fast.h | 32 + > lib/zstd/compress/zstd_fast.c | 496 ++ > lib/zstd/compress/zstd_fast.h | 31 + > lib/zstd/compress/zstd_lazy.c | 1138 +++++ > lib/zstd/compress/zstd_lazy.h | 61 + > lib/zstd/compress/zstd_ldm.c | 619 +++ > lib/zstd/compress/zstd_ldm.h | 104 + > lib/zstd/compress/zstd_opt.c | 1200 +++++ > lib/zstd/compress/zstd_opt.h | 50 + > lib/zstd/decompress.c | 2531 ---------- > lib/zstd/decompress/huf_decompress.c | 1205 +++++ > lib/zstd/decompress/zstd_ddict.c | 241 + > lib/zstd/decompress/zstd_ddict.h | 44 + > lib/zstd/decompress/zstd_decompress.c | 1836 ++++++++ > lib/zstd/decompress/zstd_decompress_block.c | 1540 ++++++ > lib/zstd/decompress/zstd_decompress_block.h | 62 + > .../decompress/zstd_decompress_internal.h | 195 + > lib/zstd/decompress_sources.h | 18 + > lib/zstd/entropy_common.c | 243 - > lib/zstd/error_private.h | 53 - > lib/zstd/fse.h | 575 --- > lib/zstd/fse_compress.c | 795 ---- > lib/zstd/fse_decompress.c | 325 -- > lib/zstd/huf.h | 212 - > lib/zstd/huf_compress.c | 772 --- > lib/zstd/huf_decompress.c | 960 ---- > lib/zstd/mem.h | 151 - > lib/zstd/zstd_common.c | 75 - > lib/zstd/zstd_compress_module.c | 79 + > lib/zstd/zstd_decompress_module.c | 79 + > lib/zstd/zstd_internal.h | 273 -- > lib/zstd/zstd_opt.h | 1014 ---- > 71 files changed, 24368 insertions(+), 13012 deletions(-) > create mode 100644 include/linux/zstd_errors.h > delete mode 100644 lib/zstd/bitstream.h > create mode 100644 lib/zstd/common/bitstream.h > create mode 100644 lib/zstd/common/compiler.h > create mode 100644 lib/zstd/common/cpu.h > create mode 100644 lib/zstd/common/debug.c > create mode 100644 lib/zstd/common/debug.h > create mode 100644 lib/zstd/common/entropy_common.c > create mode 100644 lib/zstd/common/error_private.c > create mode 100644 lib/zstd/common/error_private.h > create mode 100644 lib/zstd/common/fse.h > create mode 100644 lib/zstd/common/fse_decompress.c > create mode 100644 lib/zstd/common/huf.h > create mode 100644 lib/zstd/common/mem.h > create mode 100644 lib/zstd/common/zstd_common.c > create mode 100644 lib/zstd/common/zstd_deps.h > create mode 100644 lib/zstd/common/zstd_internal.h > delete mode 100644 lib/zstd/compress.c > create mode 100644 lib/zstd/compress/fse_compress.c > create mode 100644 lib/zstd/compress/hist.c > create mode 100644 lib/zstd/compress/hist.h > create mode 100644 lib/zstd/compress/huf_compress.c > create mode 100644 lib/zstd/compress/zstd_compress.c > create mode 100644 lib/zstd/compress/zstd_compress_internal.h > create mode 100644 lib/zstd/compress/zstd_compress_literals.c > create mode 100644 lib/zstd/compress/zstd_compress_literals.h > create mode 100644 lib/zstd/compress/zstd_compress_sequences.c > create mode 100644 lib/zstd/compress/zstd_compress_sequences.h > create mode 100644 lib/zstd/compress/zstd_compress_superblock.c > create mode 100644 lib/zstd/compress/zstd_compress_superblock.h > create mode 100644 lib/zstd/compress/zstd_cwksp.h > create mode 100644 lib/zstd/compress/zstd_double_fast.c > create mode 100644 lib/zstd/compress/zstd_double_fast.h > create mode 100644 lib/zstd/compress/zstd_fast.c > create mode 100644 lib/zstd/compress/zstd_fast.h > create mode 100644 lib/zstd/compress/zstd_lazy.c > create mode 100644 lib/zstd/compress/zstd_lazy.h > create mode 100644 lib/zstd/compress/zstd_ldm.c > create mode 100644 lib/zstd/compress/zstd_ldm.h > create mode 100644 lib/zstd/compress/zstd_opt.c > create mode 100644 lib/zstd/compress/zstd_opt.h > delete mode 100644 lib/zstd/decompress.c > create mode 100644 lib/zstd/decompress/huf_decompress.c > create mode 100644 lib/zstd/decompress/zstd_ddict.c > create mode 100644 lib/zstd/decompress/zstd_ddict.h > create mode 100644 lib/zstd/decompress/zstd_decompress.c > create mode 100644 lib/zstd/decompress/zstd_decompress_block.c > create mode 100644 lib/zstd/decompress/zstd_decompress_block.h > create mode 100644 lib/zstd/decompress/zstd_decompress_internal.h > create mode 100644 lib/zstd/decompress_sources.h > delete mode 100644 lib/zstd/entropy_common.c > delete mode 100644 lib/zstd/error_private.h > delete mode 100644 lib/zstd/fse.h > delete mode 100644 lib/zstd/fse_compress.c > delete mode 100644 lib/zstd/fse_decompress.c > delete mode 100644 lib/zstd/huf.h > delete mode 100644 lib/zstd/huf_compress.c > delete mode 100644 lib/zstd/huf_decompress.c > delete mode 100644 lib/zstd/mem.h > delete mode 100644 lib/zstd/zstd_common.c > create mode 100644 lib/zstd/zstd_compress_module.c > create mode 100644 lib/zstd/zstd_decompress_module.c > delete mode 100644 lib/zstd/zstd_internal.h > delete mode 100644 lib/zstd/zstd_opt.h > > -- > 2.28.0 >
