From: Mark Rutland <mark.rutland@arm.com>
To: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
Cc: linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, Will.Deacon@arm.com,
catalin.marinas@arm.com, acme@kernel.org,
alexander.shishkin@linux.intel.com, peterz@infradead.org,
mingo@redhat.com, jnair@caviumnetworks.com, gpkulkarni@gmail.com
Subject: Re: [PATCH 2/3] perf tools arm64: implement function get_cpuid_str
Date: Tue, 4 Apr 2017 13:25:18 +0100 [thread overview]
Message-ID: <20170404122518.GA8551@leverpostej> (raw)
In-Reply-To: <1491291403-29893-3-git-send-email-ganapatrao.kulkarni@cavium.com>
On Tue, Apr 04, 2017 at 01:06:42PM +0530, Ganapatrao Kulkarni wrote:
> function get_cpuid_str returns midr_el1 value from first
> online cpu available.
This isn't globally the same (e.g. in big.LITTLE systems).
It would be far better to have the function take a PMU, and look at the
first CPU in that PMU's mask.
Thanks,
Mark.
>
> Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
> ---
> tools/perf/arch/arm64/util/Build | 1 +
> tools/perf/arch/arm64/util/header.c | 51 +++++++++++++++++++++++++++++++++++++
> 2 files changed, 52 insertions(+)
> create mode 100644 tools/perf/arch/arm64/util/header.c
>
> diff --git a/tools/perf/arch/arm64/util/Build b/tools/perf/arch/arm64/util/Build
> index cef6fb3..b1ab72d 100644
> --- a/tools/perf/arch/arm64/util/Build
> +++ b/tools/perf/arch/arm64/util/Build
> @@ -1,3 +1,4 @@
> +libperf-y += header.o
> libperf-$(CONFIG_DWARF) += dwarf-regs.o
> libperf-$(CONFIG_LOCAL_LIBUNWIND) += unwind-libunwind.o
>
> diff --git a/tools/perf/arch/arm64/util/header.c b/tools/perf/arch/arm64/util/header.c
> new file mode 100644
> index 0000000..c0468fe
> --- /dev/null
> +++ b/tools/perf/arch/arm64/util/header.c
> @@ -0,0 +1,51 @@
> +#include <fnmatch.h>
> +#include <dirent.h>
> +#include <unistd.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <linux/stringify.h>
> +#include "header.h"
> +#include "util.h"
> +
> +#define LINUX_SYS_CPU_DIRECTORY "/sys/devices/system/cpu/"
> +#define MIDR "/regs/identification/midr_el1"
> +
> +char *get_cpuid_str(void)
> +{
> + char *buf = malloc(128);
> + FILE *file;
> + char *ret = NULL;
> + int cpu , nr_cpu;
> + char sys_file[256];
> +
> + sprintf(sys_file, LINUX_SYS_CPU_DIRECTORY"kernel_max");
> +
> + file = fopen(sys_file, "r");
> + if (!file)
> + return ret;
> +
> + if (fscanf(file, "%d", &nr_cpu) != 1)
> + return ret;
> +
> + /* kernel_max returns nr_cpu -1 */
> + nr_cpu++;
> +
> + /*iterate till you read midr of first online cpu */
> + for(cpu = 0; cpu < nr_cpu; cpu++)
> + {
> + sprintf(sys_file, LINUX_SYS_CPU_DIRECTORY"cpu%d"MIDR, cpu);
> + file = fopen(sys_file, "r");
> + if (file) {
> + ret = fgets(buf, 128, file);
> + if (ret) {
> + buf[strlen(buf)-1] ='\0';
> + fclose(file);
> + return buf;
> + }
> + fclose(file);
> + }
> + }
> + free(buf);
> + return ret;
> +}
> --
> 1.8.1.4
>
next prev parent reply other threads:[~2017-04-04 12:25 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-04 7:36 [PATCH 0/3] Add support for ThunderX2 pmu events using json files Ganapatrao Kulkarni
2017-04-04 7:36 ` [PATCH 1/3] perf jevents: Add support to use core pmu name other than cpu Ganapatrao Kulkarni
2017-04-04 7:36 ` [PATCH 2/3] perf tools arm64: implement function get_cpuid_str Ganapatrao Kulkarni
2017-04-04 12:25 ` Mark Rutland [this message]
2017-04-05 9:18 ` Ganapatrao Kulkarni
2017-04-04 7:36 ` [PATCH 3/3] perf tool, arm64, thunderx2: Add implementation defined events for ThunderX2 Ganapatrao Kulkarni
2017-04-04 12:28 ` Mark Rutland
2017-04-05 9:12 ` Ganapatrao Kulkarni
2017-04-05 10:05 ` Mark Rutland
2017-04-06 4:20 ` Ganapatrao Kulkarni
2017-04-06 9:55 ` Mark Rutland
2017-04-19 18:07 ` Ganapatrao Kulkarni
2017-04-20 8:53 ` Mark Rutland
2017-04-04 12:29 ` [PATCH 0/3] Add support for ThunderX2 pmu events using json files Mark Rutland
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