On Fri, Jul 15, 2016 at 11:08:13AM +0100, Mark Rutland wrote:
> For system PMUs, the perf tools have long expected a cpumask file under
> sysfs, describing the single CPU which they support events being
single cpu? it's cpumask..
> opened/handled on. Prior patches in this series have reworked this
> support to support multiple CPUs in a mask, as is required to handle
> heterogeneous CPU PMUs.
>
> Unfortunately, adding a cpumask file to CPU PMUs would break existing
> userspace. Prior to this series, perf record will refuse to open events,
I'm lost.. we already have 'cpumask' file under pmu..
> and perf stat may unexpectedly block at exit time. In the absence of a
> cpumask, perf stat is functional.
>
> To address this, this patch adds support for a new file,
> supported_cpumask, which can be used to describe heterogeneous CPUs,
> without the risk of breaking existing userspace binaries.
is there kernel patch adding supported_cpumask support?
thanks,
jirka
>
> Signed-off-by: Mark Rutland <mark.rutl...@arm.com>
> ---
> tools/perf/util/pmu.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index ddb0261..06c985c 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -445,14 +445,23 @@ static struct cpu_map *pmu_cpumask(const char *name)
> FILE *file;
> struct cpu_map *cpus;
> const char *sysfs = sysfs__mountpoint();
> + const char *path_template[] = {
> + "%s/bus/event_source/devices/%s/cpumask",
> + "%s/bus/event_source/devices/%s/supported_cpumask",
> + NULL
> + };
> + unsigned int i;
>
> if (!sysfs)
> return NULL;
>
> - snprintf(path, PATH_MAX,
> - "%s/bus/event_source/devices/%s/cpumask", sysfs, name);
> + for (i = 0; i < ARRAY_SIZE(path_template); i++) {
> + snprintf(path, PATH_MAX, *path_template, sysfs, name);
> + if (stat(path, &st) == 0)
> + break;
> + }
>
> - if (stat(path, &st) < 0)
> + if (!*path_template)
> return NULL;
>
> file = fopen(path, "r");
> --
> 1.9.1
>
