Re: [PATCH 06/23] perf mem: Check for memory events support

From: Arnaldo Carvalho de Melo
Date: Tue Feb 23 2016 - 10:18:24 EST


Em Mon, Feb 15, 2016 at 09:34:36AM +0100, Jiri Olsa escreveu:
> Check if current kernel support available memory events
> and display the status within -e list option:
>
> $ perf mem record -e list
> [ok] ldlat-loads
> [ok] ldlat-stores

Can't this be:

$ perf mem record -e list
ldlat-loads: Available on this machine
ldlat-stores: Available on this machine

- Arnaldo

> Link: http://lkml.kernel.org/n/tip-r8smhxjfe69q67jwt7mzs0e9@xxxxxxxxxxxxxx
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
> tools/perf/builtin-mem.c | 14 +++++++++++++-
> tools/perf/util/mem-events.c | 35 ++++++++++++++++++++++++++++++++---
> tools/perf/util/mem-events.h | 3 +++
> 3 files changed, 48 insertions(+), 4 deletions(-)
>
> diff --git a/tools/perf/builtin-mem.c b/tools/perf/builtin-mem.c
> index b3f8a89ede40..e64e0aa7ba0e 100644
> --- a/tools/perf/builtin-mem.c
> +++ b/tools/perf/builtin-mem.c
> @@ -40,7 +40,8 @@ static int parse_record_events(const struct option *opt,
> for (j = 0; j < PERF_MEM_EVENTS__MAX; j++) {
> struct perf_mem_event *e = &perf_mem_events[j];
>
> - fprintf(stderr, "%-20s%s",
> + fprintf(stderr, "%s%-20s%s",
> + e->supported ? "[ok] " : " ",
> e->tag, verbose ? "" : "\n");
> if (verbose)
> fprintf(stderr, " [%s]\n", e->name);
> @@ -92,6 +93,12 @@ static int __cmd_record(int argc, const char **argv, struct perf_mem *mem)
> if (!perf_mem_events[j].record)
> continue;
>
> + if (!perf_mem_events[j].supported) {
> + pr_err("failed: event '%s' not supported\n",
> + perf_mem_events[j].name);
> + return -1;
> + }
> +
> rec_argv[i++] = "-e";
> rec_argv[i++] = perf_mem_events[j].name;
> };
> @@ -355,6 +362,11 @@ int cmd_mem(int argc, const char **argv, const char *prefix __maybe_unused)
> NULL
> };
>
> + if (perf_mem_events__init()) {
> + pr_err("failed: memory events not supported\n");
> + return -1;
> + }
> +
> argc = parse_options_subcommand(argc, argv, mem_options, mem_subcommands,
> mem_usage, PARSE_OPT_STOP_AT_NON_OPTION);
>
> diff --git a/tools/perf/util/mem-events.c b/tools/perf/util/mem-events.c
> index b1507c04b257..e21853fe1312 100644
> --- a/tools/perf/util/mem-events.c
> +++ b/tools/perf/util/mem-events.c
> @@ -2,15 +2,20 @@
> #include <stdlib.h>
> #include <string.h>
> #include <errno.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +#include <unistd.h>
> +#include <api/fs/fs.h>
> #include "mem-events.h"
> #include "debug.h"
>
> -#define E(t, n) { .tag = t, .name = n }
> +#define E(t, n, s) { .tag = t, .name = n, .sysfs_name = s }
>
> struct perf_mem_event perf_mem_events[PERF_MEM_EVENTS__MAX] = {
> - E("ldlat-loads", "cpu/mem-loads,ldlat=30/P"),
> - E("ldlat-stores", "cpu/mem-stores/P"),
> + E("ldlat-loads", "cpu/mem-loads,ldlat=30/P", "mem-loads"),
> + E("ldlat-stores", "cpu/mem-stores/P", "mem-stores"),
> };
> +#undef E
>
> #undef E
>
> @@ -49,3 +54,27 @@ int perf_mem_events__parse(const char *str)
> pr_err("failed: event '%s' not found, use '-e list' to get list of available events\n", str);
> return -1;
> }
> +
> +int perf_mem_events__init(void)
> +{
> + const char *mnt = sysfs__mount();
> + bool found = false;
> + int j;
> +
> + if (!mnt)
> + return -ENOENT;
> +
> + for (j = 0; j < PERF_MEM_EVENTS__MAX; j++) {
> + char path[PATH_MAX];
> + struct perf_mem_event *e = &perf_mem_events[j];
> + struct stat st;
> +
> + scnprintf(path, PATH_MAX, "%s/devices/cpu/events/%s",
> + mnt, e->sysfs_name);
> +
> + if (!stat(path, &st))
> + e->supported = found = true;
> + }
> +
> + return found ? 0 : -ENOENT;
> +}
> diff --git a/tools/perf/util/mem-events.h b/tools/perf/util/mem-events.h
> index 0b5247468462..b9a786346c03 100644
> --- a/tools/perf/util/mem-events.h
> +++ b/tools/perf/util/mem-events.h
> @@ -5,8 +5,10 @@
>
> struct perf_mem_event {
> bool record;
> + bool supported;
> const char *tag;
> const char *name;
> + const char *sysfs_name;
> };
>
> enum {
> @@ -18,6 +20,7 @@ enum {
> extern struct perf_mem_event perf_mem_events[PERF_MEM_EVENTS__MAX];
>
> int perf_mem_events__parse(const char *str);
> +int perf_mem_events__init(void);
>
> #endif /* __PERF_MEM_EVENTS_H */
>
> --
> 2.4.3