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

[Arnaldo Carvalho de Melo <acme@kernel.org>]

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@git.kernel.org
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>  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