# \[RFC PATCH for 4.21 02/16\] rseq/selftests: Adapt number of threads to the number of detected cpus

- From: Mathieu Desnoyers \<mathieu.desnoyers@efficios.com\>
- Date: 2018-10-10 19:20:22 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2018/10/5404699
- Thread: https://ratatoskr.run/linux-api/2018/10/5404697/t.md

```text
On smaller systems, running a test with 200 threads can take a long
time on machines with smaller number of CPUs.

Detect the number of online cpus at test runtime, and multiply that
by 6 to have 6 rseq threads per cpu preempting each other.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <redacted>
Cc: Joel Fernandes <redacted>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Watson <redacted>
Cc: Will Deacon <redacted>
Cc: Andi Kleen <redacted>
Cc: <redacted>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Chris Lameter <redacted>
Cc: Russell King <redacted>
Cc: Michael Kerrisk <redacted>
Cc: "Paul E . McKenney" <redacted>
Cc: Paul Turner <redacted>
Cc: Boqun Feng <redacted>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Maurer <redacted>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
---
 tools/testing/selftests/rseq/run_param_test.sh | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/rseq/run_param_test.sh b/tools/testing/selftests/rseq/run_param_test.sh
index 3acd6d75ff9f..e426304fd4a0 100755
--- a/tools/testing/selftests/rseq/run_param_test.sh
+++ b/tools/testing/selftests/rseq/run_param_test.sh
@@ -1,6 +1,8 @@
 #!/bin/bash
 # SPDX-License-Identifier: GPL-2.0+ or MIT
 
+NR_CPUS=`grep '^processor' /proc/cpuinfo | wc -l`
+
 EXTRA_ARGS=${@}
 
 OLDIFS="$IFS"
@@ -28,15 +30,16 @@ IFS="$OLDIFS"
 
 REPS=1000
 SLOW_REPS=100
+NR_THREADS=$((6*${NR_CPUS}))
 
 function do_tests()
 {
 	local i=0
 	while [ "$i" -lt "${#TEST_LIST[@]}" ]; do
 		echo "Running test ${TEST_NAME[$i]}"
-		./param_test ${TEST_LIST[$i]} -r ${REPS} ${@} ${EXTRA_ARGS} || exit 1
+		./param_test ${TEST_LIST[$i]} -r ${REPS} -t ${NR_THREADS} ${@} ${EXTRA_ARGS} || exit 1
 		echo "Running compare-twice test ${TEST_NAME[$i]}"
-		./param_test_compare_twice ${TEST_LIST[$i]} -r ${REPS} ${@} ${EXTRA_ARGS} || exit 1
+		./param_test_compare_twice ${TEST_LIST[$i]} -r ${REPS} -t ${NR_THREADS} ${@} ${EXTRA_ARGS} || exit 1
 		let "i++"
 	done
 }
-- 
2.11.0
```