Le 27/09/2016 à 16:10, Rui Teng a écrit :

From: Anton Blanchard anton@au.ibm.com

Pull in a version of Anton's null_syscall benchmark: http://ozlabs.org/~anton/junkcode/null_syscall.c Into tools/testing/selftests/powerpc/benchmarks.

Suggested-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Anton Blanchard anton@au.ibm.com Signed-off-by: Rui Teng rui.teng@linux.vnet.ibm.com

---

.../testing/selftests/powerpc/benchmarks/Makefile | 2 +- .../selftests/powerpc/benchmarks/null_syscall.c | 157 +++++++++++++++++++++ 2 files changed, 158 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/powerpc/benchmarks/null_syscall.c

[...]

+static void do_null_syscall(unsigned long nr) +{

• unsigned long i;
• for (i = 0; i < nr; i++)

• getppid();
  

+}

Looks like getppid() performs a rcu_read_lock(). Is that what we want ?

Shouldn't we use getpid() instead for a lighter syscall ?

Christophe