On Thu, Feb 23, 2023 at 9:17 AM André Almeida <andrealmeid@xxxxxxxxxx> wrote: > > As it's done for zstd compression, enable multithread compression for > xz to speed up module installation. > > Signed-off-by: André Almeida <andrealmeid@xxxxxxxxxx> > --- > > On my setup xz is a bottleneck during module installation. Here are the > numbers to install it in a local directory, before and after this patch: > > $ time make INSTALL_MOD_PATH=/home/tonyk/codes/.kernel_deploy/ modules_install -j16 > Executed in 100.08 secs > > $ time make INSTALL_MOD_PATH=/home/tonyk/codes/.kernel_deploy/ modules_install -j16 > Executed in 28.60 secs Heh, this is an interesting benchmark. Without this patch, you ran 16 processes of 'xz' in parallel since you gave -j16. You created multi-threads in each xz process, then you got 3x faster. What made it happen? How many threads can your system run? I did not get such an improvement in my testing. In my machine $(nproc) is 24. [Without this patch] $ time make INSTALL_MOD_PATH=/tmp/inst1 modules_install -j$(nproc) real 0m33.965s user 10m6.118s sys 0m37.231s [With this patch] $ time make INSTALL_MOD_PATH=/tmp/inst1 modules_install -j$(nproc) real 0m32.568s user 10m4.472s sys 0m39.132s Given that GNU Make provides the parallel execution environment, you can control the number of processes of 'xz'. There is no point in forcing multi-threading, which the user did not ask or ever want. > --- > scripts/Makefile.modinst | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/scripts/Makefile.modinst b/scripts/Makefile.modinst > index 4815a8e32227..28dcc523d2ee 100644 > --- a/scripts/Makefile.modinst > +++ b/scripts/Makefile.modinst > @@ -99,7 +99,7 @@ endif > quiet_cmd_gzip = GZIP $@ > cmd_gzip = $(KGZIP) -n -f $< > quiet_cmd_xz = XZ $@ > - cmd_xz = $(XZ) --lzma2=dict=2MiB -f $< > + cmd_xz = $(XZ) --lzma2=dict=2MiB -f -T0 $< > quiet_cmd_zstd = ZSTD $@ > cmd_zstd = $(ZSTD) -T0 --rm -f -q $< > > -- > 2.39.2 > -- Best Regards Masahiro Yamada
