Re: [PATCH RFC V2 1/1] x86, perf: Add a freq pmu driver

Jiri Olsa
2015-07-26T16:31:09Z

On Mon, Jul 20, 2015 at 11:49:06AM -0400, Kan Liang wrote:
> From: Andy Lutomirski <luto@kernel.org>
>
> This patch adds freq PMU to support time and freq related counters
> includes TSC, IA32_APERF, IA32_MPERF and IA32_PPERF.
>
> The events are exposed in sysfs for use by perf stat and other tools.
> The files are under /sys/devices/freq/events/
>
> These events only support system-wide mode counting.
>
> The PMU type (attr->type) is PERF_TYPE_FREQ.
>
> Example:
>
> To caculate the CPU%
> CPU_Utilization = CPU_CLK_UNHALTED.REF_TSC / TSC
>
> $ perf stat -e '{ref-cycles,freq/tsc/}' -C0 -- taskset -c 0 sleep 1
> 3164023,,ref-cycles,1048387386,100.00
> 2410812089,,freq/tsc/,1050022373,100.00
> The CPU% for sleep is 0.13%.
>
> $ perf stat -e '{ref-cycles,freq/tsc/}' -C0 -- taskset -c 0 busyloop
> 15662183572,,ref-cycles,6822637855,100.00
> 15667608992,,freq/tsc/,6823978523,100.00
> The CPU% for busy loop is 99.9%.
>
> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> Signed-off-by: Kan Liang <kan.liang@intel.com>

SNIP

> diff --git a/arch/x86/kernel/cpu/perf_event_freq.c b/arch/x86/kernel/cpu/perf_event_freq.c
> new file mode 100644
> index 0000000..9389b3b
> --- /dev/null
> +++ b/arch/x86/kernel/cpu/perf_event_freq.c
> @@ -0,0 +1,207 @@
> +#include <linux/perf_event.h>
> +
> +enum perf_freq_id {
> + /*
> + * freq events, generalized by the kernel:
> + */
> + PERF_FREQ_TSC = 0,
> + PERF_FREQ_APERF = 1,
> + PERF_FREQ_MPERF = 2,
> + PERF_FREQ_PPERF = 3,
> +
> + PERF_FREQ_EVENT_MAX, /* non-ABI */

should this be in uapi header?

jirka