[PATCH] package_rpm: use zstd instead of xz

[PATCH] package_rpm: use zstd instead of xz

[Alexander Kanavin]

zstd has similar time and space performance in compression but is
vastly faster in decompression, which benefits rootfs creation
(especially when installing very large packages) and on-target
package installation.

Also, ensure ZSTD_THREADS doesn't change sstate checksums. The
detailed explanation is in the commit making similar change for
XZ_THREADS.

Signed-off-by: Alexander Kanavin <alex.kanavin@gmail.com>
---
 meta/classes/package_rpm.bbclass | 4 ++--
 meta/conf/bitbake.conf           | 4 ++++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/meta/classes/package_rpm.bbclass b/meta/classes/package_rpm.bbclass
index 1c62d8283b..e738806fd7 100644
--- a/meta/classes/package_rpm.bbclass
+++ b/meta/classes/package_rpm.bbclass
@@ -684,8 +684,8 @@ python do_package_rpm () {
     cmd = cmd + " --define '_use_internal_dependency_generator 0'"
     cmd = cmd + " --define '_binaries_in_noarch_packages_terminate_build 0'"
     cmd = cmd + " --define '_build_id_links none'"
-    cmd = cmd + " --define '_binary_payload w6T%d.xzdio'" % int(d.getVar("XZ_THREADS"))
-    cmd = cmd + " --define '_source_payload w6T%d.xzdio'" % int(d.getVar("XZ_THREADS"))
+    cmd = cmd + " --define '_binary_payload w19T%d.zstdio'" % int(d.getVar("ZSTD_THREADS"))
+    cmd = cmd + " --define '_source_payload w19T%d.zstdio'" % int(d.getVar("ZSTD_THREADS"))
     cmd = cmd + " --define 'clamp_mtime_to_source_date_epoch 1'"
     cmd = cmd + " --define 'use_source_date_epoch_as_buildtime 1'"
     cmd = cmd + " --define '_buildhost reproducible'"
diff --git a/meta/conf/bitbake.conf b/meta/conf/bitbake.conf
index e25d632dc1..1ae377750b 100644
--- a/meta/conf/bitbake.conf
+++ b/meta/conf/bitbake.conf
@@ -815,6 +815,10 @@ XZ_THREADS[vardepvalue] = "1"
 XZ_DEFAULTS ?= "--memlimit=${XZ_MEMLIMIT} --threads=${XZ_THREADS}"
 XZ_DEFAULTS[vardepsexclude] += "XZ_MEMLIMIT XZ_THREADS"
 
+# Default parallelism for zstd
+ZSTD_THREADS ?= "${@oe.utils.cpu_count(at_least=2)}"
+ZSTD_THREADS[vardepvalue] = "1"
+
 # Limit the number of threads that OpenMP libraries will use. Otherwise they
 # may fallback to using all CPUs
 export OMP_NUM_THREADS = "${BB_NUMBER_THREADS}"
-- 
2.31.1