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

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Message-ID: <20150726163101.GA24646@krava.brq.redhat.com>
Date:	Sun, 26 Jul 2015 18:31:01 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	Kan Liang <kan.liang@...el.com>
Cc:	a.p.zijlstra@...llo.nl, mingo@...hat.com, acme@...nel.org,
	eranian@...gle.com, ak@...ux.intel.com, mark.rutland@....com,
	adrian.hunter@...el.com, dsahern@...il.com, jolsa@...nel.org,
	namhyung@...nel.org, linux-kernel@...r.kernel.org,
	Andy Lutomirski <luto@...nel.org>
Subject: Re: [PATCH RFC V2 1/1] x86, perf: Add a freq pmu driver

On Mon, Jul 20, 2015 at 11:49:06AM -0400, Kan Liang wrote:
> From: Andy Lutomirski <luto@...nel.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@...nel.org>
> Signed-off-by: Kan Liang <kan.liang@...el.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
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