Messages in this thread | | | Date | Tue, 4 Apr 2017 13:25:18 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH 2/3] perf tools arm64: implement function get_cpuid_str |
| |
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 >
| |