diff options
| author | Nick Terrell <terrelln@fb.com> | 2021-11-17 02:11:39 +0300 |
|---|---|---|
| committer | Nick Terrell <terrelln@fb.com> | 2021-11-19 00:16:22 +0300 |
| commit | 7416cdc9b9c10968c57b1f73be5d48b3ecdaf3c8 (patch) | |
| tree | 7471cc914ded1973d5ded539aea86c5b3b46db50 /lib | |
| parent | 1974990cca43a6ba708a70b15862113eb9c2f399 (diff) | |
| download | linux-7416cdc9b9c10968c57b1f73be5d48b3ecdaf3c8.tar.xz | |
lib: zstd: Don't add -O3 to cflags
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>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/zstd/Makefile | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/lib/zstd/Makefile b/lib/zstd/Makefile index 65218ec5b8f2..fc45339fc3a3 100644 --- a/lib/zstd/Makefile +++ b/lib/zstd/Makefile @@ -11,8 +11,6 @@ obj-$(CONFIG_ZSTD_COMPRESS) += zstd_compress.o obj-$(CONFIG_ZSTD_DECOMPRESS) += zstd_decompress.o -ccflags-y += -O3 - zstd_compress-y := \ zstd_compress_module.o \ common/debug.o \ |