[PATCH] kbuild: modinst: Enable multithread xz compression

[André Almeida]

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
---
 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