On Thu, Jul 25, 2024 at 9:23 PM Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote:
>
> dileks@iniza:~/src/linux/git$ git grep zstd scripts/ | egrep '\-(19|22|T0)'
> scripts/Makefile.lib: cmd_zstd = cat $(real-prereqs) | $(ZSTD) -19 > $@
> scripts/Makefile.lib: cmd_zstd22 = cat $(real-prereqs) | $(ZSTD)
> -22 --ultra > $@
> scripts/Makefile.lib: cmd_zstd22_with_size = { cat
> $(real-prereqs) | $(ZSTD) -22 --ultra; $(size_append); } > $@
> scripts/Makefile.modinst: cmd_zstd = $(ZSTD) -T0 --rm -f -q $<
>
> -sed@-
>
> On Thu, Jul 25, 2024 at 9:09 PM Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote:
> >
> > Hi,
> >
> > I am a big fan of ZSTD - here version 1.5.6 on Debian/unstable AMD64.
> >
> > When playing with CONFIG_MODULE_COMPRESS_ZSTD=y I observed a 35MiB
> > greater linux-image Debian file.
> >
> > Debian: ~100MiB <--- CONFIG_MODULE_COMPRESS_XZ=y
> > Selfmade: ~135MiB <--- CONFIG_MODULE_COMPRESS_ZSTD=y
> >
> > So, I checked the used compression-level of ZSTD in the build-process:
> >
> > [ vmlinux.bin.zst ]
> > $ grep zstd build-log_6.10.1-1-amd64-clang18-kcfi.txt | grep vmlinux.bin.zst
> > { cat arch/x86/boot/compressed/vmlinux.bin
> > arch/x86/boot/compressed/vmlinux.relocs | zstd -22 --ultra; printf
> > \370\040\157\003; } > arch/x86/boot/compressed/vmlinux.
> > bin.zst
> >
> > [ amdgpu.ko.zst ]
> > $ grep zstd build-log_6.10.1-1-amd64-clang18-kcfi.txt | grep '\-T0' |
> > grep amdgpu
> > zstd -T0 --rm -f -q
> > debian/linux-image-6.10.1-1-amd64-clang18-kcfi/lib/modules/6.10.1-1-amd64-clang18-kcfi/kernel/drivers/gpu/drm/amd/amdgpu/amdgpu.ko
> >
> > Here some numbers:
> >
> > [ Values in KiB ]
> > $ du -k amdgpu.ko*
> > 29264 amdgpu.ko
> > 5672 amdgpu.ko.zst <--- XXX: -T0
> > 4264 amdgpu.ko.zst_T0-19 <--- XXX: -T0 -19
> > 4260 amdgpu.ko.zst_T0-22
> > 4308 amdgpu.ko.zst_T0-22-ultra
> >
> > $ time zstd -T0 -v amdgpu.ko
> > *** Zstandard CLI (64-bit) v1.5.6, by Yann Collet ***
> > Note: 2 physical core(s) detected
> > zstd: amdgpu.ko.zst already exists; overwrite (y/n) ? y
> > amdgpu.ko : 19.38% ( 28.6 MiB => 5.54 MiB, amdgpu.ko.zst)
> >
> > real 0m2,496s
> > user 0m0,448s
> > sys 0m0,064s
> >
> > $ time zstd -T0 -19 -v amdgpu.ko
> > *** Zstandard CLI (64-bit) v1.5.6, by Yann Collet ***
> > Note: 2 physical core(s) detected
> > amdgpu.ko : 14.56% ( 28.6 MiB => 4.16 MiB, amdgpu.ko.zst)
> >
> > real 0m22,821s
> > user 0m22,759s
> > sys 0m0,080s
> >
> > My wish is to use the zstd-option "-T0" (see vmlinux.bin.zst) everywhere.
> >
> > For CONFIG_MODULE_COMPRESS_ZSTD=y: Add compress-level = -19
> >
> > NOTE: -22 w/ or w/o ultra has no big effect here and increases even
> > more build-time.
> >
> > What do you think?
> >
> > Thanks.
> >
> > Best regards,
> > -Sedat-
[ Adding some more folks - kmod / authors of commit c3d7ef377eb2
("kbuild: add support for zstd compressed modules") ]
Debian/unstable AMD54 ships kmod version 32+20240611-1.
To use better/higher ZSTD compression-level for
CONFIG_MODULE_COMPRESS_ZSTD=y - do we need a newer KMOD version?
DIFF for Linux-6.10.1:
$ git diff scripts/Makefile.modinst
diff --git a/scripts/Makefile.modinst b/scripts/Makefile.modinst
index 0afd75472679..2a8b37c80cbf 100644
--- a/scripts/Makefile.modinst
+++ b/scripts/Makefile.modinst
@@ -146,7 +146,7 @@ quiet_cmd_gzip = GZIP $@
quiet_cmd_xz = XZ $@
cmd_xz = $(XZ) --check=crc32 --lzma2=dict=1MiB -f $<
quiet_cmd_zstd = ZSTD $@
- cmd_zstd = $(ZSTD) -T0 --rm -f -q $<
+ cmd_zstd = $(ZSTD) -T0 -19 --rm -f -q $<
$(dst)/%.ko.gz: $(dst)/%.ko FORCE
$(call cmd,gzip)
Thanks.
BR,
-sed@-
