On Fri, Dec 17, 2021 at 9:51 AM Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote: > > On Wed, Nov 24, 2021 at 4:30 PM Alex Xu (Hello71) <alex_y_xu@xxxxxxxx> wrote: > > > > Otherwise, it allocates 2 GB of memory at once. Even though the majority > > of this memory is never touched, the default heuristic overcommit > > refuses this request if less than 2 GB of RAM+swap is currently > > available. This results in "zstd: error 11 : Allocation error : not > > enough memory" and the kernel failing to build. > > > > When the size is specified, zstd will reduce the memory request > > appropriately. For typical kernel sizes of ~32 MB, the largest mmap > > request will be reduced to 512 MB, which will succeed on all but the > > smallest devices. > > > > For inputs around this size, --stream-size --no-content-size may > > slightly decrease the compressed size, or slightly increase it: > > https://github.com/facebook/zstd/issues/2848. > > > > Hi Alex and Nick T., > > some questions: > > Can I apply this patch as a single patch - without patch 1/2? > > Is there an impact also on the kernel's ZRAM/ZSWAP support plus using > ZSTD as (de)comp-algo? > > Here I have: > > $ grep -i zstd /boot/config-5.15.7-1-amd64-clang13-lto | egrep -i 'zram|zswap' > CONFIG_ZSWAP_COMPRESSOR_DEFAULT_ZSTD=y > CONFIG_ZSWAP_COMPRESSOR_DEFAULT="zstd" > CONFIG_ZRAM_DEF_COMP_ZSTD=y > CONFIG_ZRAM_DEF_COMP="zstd" > $ egrep 'stream-size' build-log_5.15.9-1-amd64-clang13-lto.txt 49360: { cat arch/x86/boot/compressed/vmlinux.bin arch/x86/boot/compressed/vmlinux.relocs | zstd --stream-size=53340760 --no-content-size -22 --ultra; printf \130\352 \055\003; } > arch/x86/boot/compressed/vmlinux.bin.zst Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx> - Sedat - > Thanks. > > Regards, > - Sedat - > > > Signed-off-by: Alex Xu (Hello71) <alex_y_xu@xxxxxxxx> > > --- > > scripts/Makefile.lib | 12 ++++++++++-- > > 1 file changed, 10 insertions(+), 2 deletions(-) > > > > diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib > > index ca901814986a..c98a82ca38e6 100644 > > --- a/scripts/Makefile.lib > > +++ b/scripts/Makefile.lib > > @@ -466,12 +466,20 @@ quiet_cmd_xzmisc = XZMISC $@ > > # single pass, so zstd doesn't need to allocate a window buffer. When streaming > > # decompression is used, like initramfs decompression, zstd22 should likely not > > # be used because it would require zstd to allocate a 128 MB buffer. > > +# > > +# --stream-size to reduce zstd memory usage (otherwise zstd -22 --ultra > > +# allocates, but does not use, 2 GB) and potentially improve compression. > > +# > > +# --no-content-size to save three bytes which we do not use (we use size_append). > > + > > +# zstd --stream-size is only supported since 1.4.4 > > +zstd_stream_size = $(shell $(ZSTD) -1c --stream-size=0 --no-content-size </dev/null >/dev/null 2>&1 && printf '%s' '--stream-size=$(total_size) --no-content-size') > > > > quiet_cmd_zstd = ZSTD $@ > > - cmd_zstd = { cat $(real-prereqs) | $(ZSTD) -19; $(size_append); } > $@ > > + cmd_zstd = { cat $(real-prereqs) | $(ZSTD) $(zstd_stream_size) -19; $(size_append); } > $@ > > > > quiet_cmd_zstd22 = ZSTD22 $@ > > - cmd_zstd22 = { cat $(real-prereqs) | $(ZSTD) -22 --ultra; $(size_append); } > $@ > > + cmd_zstd22 = { cat $(real-prereqs) | $(ZSTD) $(zstd_stream_size) -22 --ultra; $(size_append); } > $@ > > > > # ASM offsets > > # --------------------------------------------------------------------------- > > -- > > 2.34.0 > >
