| Message ID | 20201103060535.8460-1-nickrterrell@gmail.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Update to zstd-1.4.6 | expand |
On 11/3/20 1:05 AM, Nick Terrell wrote: > From: Nick Terrell <terrelln@fb.com> > > Please pull from > > git@github.com:terrelln/linux.git tags/v5-zstd-1.4.6 > > to get these changes. Alternatively the patchset is included. > Where did we come down on the code formatting question? Personally I'm of the mind that as long as the consumers themselves adhere to the proper coding style I'm fine not maintaining the code style as long as we get the benefit of easily syncing in code from the upstream project. Thanks, Josef
> On Nov 6, 2020, at 9:15 AM, Josef Bacik <josef@toxicpanda.com> wrote: > > On 11/3/20 1:05 AM, Nick Terrell wrote: >> From: Nick Terrell <terrelln@fb.com> >> Please pull from >> git@github.com:terrelln/linux.git tags/v5-zstd-1.4.6 >> to get these changes. Alternatively the patchset is included. > > Where did we come down on the code formatting question? Personally I'm of the mind that as long as the consumers themselves adhere to the proper coding style I'm fine not maintaining the code style as long as we get the benefit of easily syncing in code from the upstream project. Thanks, The general consensus of everyone who has been involved in the discussion so far, seems to be that the benefits of keeping zstd in-sync with upstream outweigh the cost of accepting upstream’s API, though not everyone agrees. The alternative is to provide a wrapper around upstream’s API, but this makes it slightly harder to debug, since you have to go through the wrapper whose only purpose is to adapt to the coding style, and allows bugs to sneak into the kernel implementation, which aren’t present upstream. Additionally, in 2017 LZ4 switched to using upstream LZ4’s API in order to stay up to date with upstream, which sets precedent. I also help maintain LZ4, and once the zstd update is merged, I plan to work on making it easier to update LZ4 in the kernel when upstream updates. That will be a much smaller change, since LZ4 is already nearly using upstream’s code directly. Best, Nick
From: Nick Terrell <terrelln@fb.com> Please pull from git@github.com:terrelln/linux.git tags/v5-zstd-1.4.6 to get these changes. Alternatively the patchset is included. 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. v4 -> v5: * Rebase onto v5.10-rc2 * (6/9) Merge with other F2FS changes (no functional change in patch). 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 | 99 +- 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, 24367 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