[dpdk-stable] [PATCH] app/test: fix dependency on file in /sys

[dpdk-stable] [PATCH] app/test: fix dependency on file in /sys

[Bruce Richardson]

Meson versions 0.52 and 0.53 are being overly smart and detecting the path
"/sys/devices/system/cpu/present" in the call to cat in
app/test/meson.build and then adding it as a dependency to the build
configuration. This causes issues on systems where the timestamp of that
file always returns the current time, since it means that the build.ninja
file is always out of date, and therefore needs to be rebuilt.

We can fix this by just using a simple shell script to return the coremask
appropriately for BSD and Linux, and removing that code logic from meson -
thereby hiding the use of the /sys file.

Fixes: c70622ac6f72 ("test: detect number of cores with meson")
Cc: aconole@redhat.com
Cc: stable@dpdk.org

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 app/test/get-coremask.sh | 13 +++++++++++++
 app/test/meson.build     | 16 ++--------------
 2 files changed, 15 insertions(+), 14 deletions(-)
 create mode 100755 app/test/get-coremask.sh

diff --git a/app/test/get-coremask.sh b/app/test/get-coremask.sh
new file mode 100755
index 000000000..0bb61c858
--- /dev/null
+++ b/app/test/get-coremask.sh
@@ -0,0 +1,13 @@
+#! /bin/sh -e
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright(c) 2019 Intel Corporation
+
+if [ "$(uname)" = "Linux" ] ; then
+	cat /sys/devices/system/cpu/present
+elif [ "$(uname)" = "FreeBSD" ] ; then
+	ncpus=$(/sbin/sysctl -n hw.ncpu)
+	echo 0-$(expr $ncpus - 1)
+else
+# fallback
+	echo 0-3
+fi
diff --git a/app/test/meson.build b/app/test/meson.build
index fb49d804b..22b0cefaa 100644
--- a/app/test/meson.build
+++ b/app/test/meson.build
@@ -398,20 +398,8 @@ dpdk_test = executable('dpdk-test',
 timeout_seconds = 600
 timeout_seconds_fast = 10
 
-# Retrieve the number of CPU cores, defaulting to 4.
-num_cores = '0-3'
-if host_machine.system() == 'linux'
-	num_cores = run_command('cat',
-				'/sys/devices/system/cpu/present'
-			       ).stdout().strip()
-elif host_machine.system() == 'freebsd'
-	snum_cores = run_command('/sbin/sysctl', '-n',
-				 'hw.ncpu').stdout().strip()
-	inum_cores = snum_cores.to_int() - 1
-        num_cores = '0-@0@'.format(inum_cores)
-endif
-
-num_cores_arg = '-l ' + num_cores
+get_coremask = find_program('get-coremask.sh')
+num_cores_arg = '-l ' + run_command(get_coremask).stdout().strip()
 
 test_args = [num_cores_arg]
 foreach arg : fast_test_names
-- 
2.20.1

Re: [dpdk-stable] [PATCH] app/test: fix dependency on file in /sys

[Thomas Monjalon]

20/01/2020 13:22, Bruce Richardson:
> Meson versions 0.52 and 0.53 are being overly smart and detecting the path
> "/sys/devices/system/cpu/present" in the call to cat in
> app/test/meson.build and then adding it as a dependency to the build
> configuration. This causes issues on systems where the timestamp of that
> file always returns the current time, since it means that the build.ninja
> file is always out of date, and therefore needs to be rebuilt.
> 
> We can fix this by just using a simple shell script to return the coremask
> appropriately for BSD and Linux, and removing that code logic from meson -
> thereby hiding the use of the /sys file.
> 
> Fixes: c70622ac6f72 ("test: detect number of cores with meson")
> Cc: aconole@redhat.com
> Cc: stable@dpdk.org
> 
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>

Thanks a lot Bruce, meson stops reconfiguring, this is a life changer!

Applied (with new script added in MAINTAINERS), thanks