Disable ASM in the kernel for now. It requires a few changes & setup to
get working. Instead of doing it in a zstd version update, I'd prefer to
package that change as a single patch, and propose it separately from
the version update. This makes the version update easier, and reduces
some risk.
Use a switch statement to select the search function instead of an
indirect function call. This results in a sizable performance win.
This PR is a modification of the approach taken in PR #2828.
When I measured performance for that commit, it was neutral.
However, I now see a performance regression on gcc, but still
neutral on clang. I'm measuring on the same platform, but with
newer compilers. The new approach beats both the current dev
branch and the baseline before PR #2828 was merged.
This PR is necessary for Issue #3275, to update zstd in the kernel.
Without this PR there is a large regression in greedy - btlazy2
compression speed. With this PR it is about neutral.
gcc version: 12.2.0
clang version: 14.0.6
dataset: silesia.tar
| Compiler | Level | Dev Speed (MB/s) | PR Speed (MB/s) | Delta |
|----------|-------|------------------|-----------------|--------|
| gcc | 5 | 102.6 | 113.7 | +10.8% |
| gcc | 7 | 66.6 | 74.8 | +12.3% |
| gcc | 9 | 51.5 | 58.9 | +14.3% |
| gcc | 13 | 14.3 | 14.3 | +0.0% |
| clang | 5 | 108.1 | 114.8 | +6.2% |
| clang | 7 | 68.5 | 72.3 | +5.5% |
| clang | 9 | 53.2 | 56.2 | +5.6% |
| clang | 13 | 14.3 | 14.7 | +2.8% |
The binary size stays just about the same for clang and gcc, measured
using the `size` command:
| Compiler | Branch | Text | Data | BSS | Total |
|----------|--------|---------|------|-----|---------|
| gcc | dev | 1127950 | 3312 | 280 | 1131542 |
| gcc | PR | 1123422 | 2512 | 280 | 1126214 |
| clang | dev | 1046254 | 3256 | 216 | 1049726 |
| clang | PR | 1048198 | 2296 | 216 | 1050710 |
Add a `--spdx` option to the freestanding script to prefix
files with a line like (for `.c` files):
// SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
or (for `.h` and `.S` files):
/* SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause */
Given the style of the line to be used depends on the extension,
a simple `sed` insert command would not work.
It also skips the file if an existing SPDX line is there,
as well as raising an error if an unexpected SPDX line appears
anywhere else in the file, as well as for unexpected
file extensions.
I double-checked that all currently generated files appear
to be license as expected with:
grep -LRF 'This source code is licensed under both the BSD-style license (found in the' linux/lib/zstd
grep -LRF 'LICENSE file in the root directory of this source tree) and the GPLv2 (found' linux/lib/zstd
but somebody knowledgable on the licensing of the project should
double-check this is the intended case.
Fixes: https://github.com/facebook/zstd/issues/3293
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Currently this function actually reads the dict ID from the dictionary's
header, via `ZSTD_getDictID_fromDict()`. But during decompression the decomp-
ressor actually compares the dict ID in the frame header with the dict ID in
the DDict. Now of course the dict ID in the dictionary contents and the dict
ID in the DDict struct *should* be the same. But in cases of memory corrupt-
ion, where they can drift out of sync, it's misleading for this function to
read it again from the dict buffer rather then return the dict ID that will
actually be used.
Also doing it this way avoids rechecking the magic and so on and so it is a
tiny bit more efficient.
Since your Makefile uses obj/$(HASH_DIR) for object files, this code does not work correctly for GCC. Because profiles are saved in one directory, and are expected in another when reading.
`$(RM) zstd *.o` - this line doesn't delete object files.
Clang stores profiles in the current directory, so the problem doesn't appear when compiling with Clang.
Also this code will work if BUILD_DIR is set.
Clang doesn't allow [[deprecated(...)]] attribute after __attribute__.
Move [[deprecated(...)]] before __attribute__ to fix C++14/C++17 uses
with Clang.
Fix#3250
