[LTP] [PATCH 2/2] perf_event_open02: make test more reliable on -rt kernels

[Cyril Hrubis]

Hi!
> Signed-off-by: Jan Stancek <jstancek@redhat.com>
> ---
>  .../kernel/syscalls/perf_event_open/perf_event_open02.c   | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/testcases/kernel/syscalls/perf_event_open/perf_event_open02.c b/testcases/kernel/syscalls/perf_event_open/perf_event_open02.c
> index 1cfe29bb3d8a..6fc6f4afa119 100644
> --- a/testcases/kernel/syscalls/perf_event_open/perf_event_open02.c
> +++ b/testcases/kernel/syscalls/perf_event_open/perf_event_open02.c
> @@ -52,6 +52,7 @@ Usage is: ./performance_counter02  [-v]
>  The -v flag makes it print out the values of each counter.
>  */
>  
> +#define _GNU_SOURCE
>  #include <stdio.h>
>  #include <stddef.h>
>  #include <stdlib.h>
> @@ -222,6 +223,20 @@ static void setup(void)
>  	int i;
>  	struct perf_event_attr tsk_event, hw_event;
>  
> +#ifdef HAVE_SCHED_GETCPU
> +	cpu_set_t mask;

Don't we have to allocate the mask dynamically so that we do not fail on
systems with more than CPU_SETSIZE (1024) CPUs?

We already have fallback macros for older libc in include/lapi/cpuset.h
so that we can use CPU_ALLOC() unconditionally.

> +	int cpu = sched_getcpu();
> +
> +	if (cpu == -1)
> +		tst_brkm(TBROK | TERRNO, NULL, "sched_getcpu() failed");
> +
> +	CPU_ZERO(&mask);
> +	CPU_SET(cpu, &mask);
> +
> +	if (sched_setaffinity(0, sizeof(cpu_set_t), &mask) == -1)
> +		tst_brkm(TBROK | TERRNO, NULL, "sched_setaffinity() failed");
> +#endif
> +
>  	/*
>  	 * According to perf_event_open's manpage, the official way of
>  	 * knowing if perf_event_open() support is enabled is checking for
> -- 
> 1.8.3.1
> 
> 
> -- 
> Mailing list info: https://lists.linux.it/listinfo/ltp

-- 
Cyril Hrubis
chrubis@suse.cz