Re: [PATCH v3 2/2] perf stat: Support regex pattern in --for-each-cgroup

[Jiri Olsa]

On Tue, Oct 27, 2020 at 04:28:55PM +0900, Namhyung Kim wrote:
> To make the command line even more compact with cgroups, support regex
> pattern matching in cgroup names.
> 
>   $ perf stat -a -e cpu-clock,cycles --for-each-cgroup ^foo sleep 1
> 
>           3,000.73 msec cpu-clock                 foo #    2.998 CPUs utilized
>     12,530,992,699      cycles                    foo #    7.517 GHz                      (100.00%)
>           1,000.61 msec cpu-clock                 foo/bar #    1.000 CPUs utilized
>      4,178,529,579      cycles                    foo/bar #    2.506 GHz                      (100.00%)
>           1,000.03 msec cpu-clock                 foo/baz #    0.999 CPUs utilized
>      4,176,104,315      cycles                    foo/baz #    2.505 GHz                      (100.00%)
> 
>        1.000892614 seconds time elapsed
> 
> Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>

Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>

thanks,
jirka

> ---
>  tools/perf/Documentation/perf-stat.txt |   5 +-
>  tools/perf/builtin-stat.c              |   5 +-
>  tools/perf/util/cgroup.c               | 198 ++++++++++++++++++++++---
>  3 files changed, 182 insertions(+), 26 deletions(-)
> 
> diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
> index 9f9f29025e49..2b44c08b3b23 100644
> --- a/tools/perf/Documentation/perf-stat.txt
> +++ b/tools/perf/Documentation/perf-stat.txt
> @@ -168,8 +168,9 @@ command line can be used: 'perf stat -e cycles -G cgroup_name -a -e cycles'.
>  
>  --for-each-cgroup name::
>  Expand event list for each cgroup in "name" (allow multiple cgroups separated
> -by comma).  This has same effect that repeating -e option and -G option for
> -each event x name.  This option cannot be used with -G/--cgroup option.
> +by comma).  It also support regex patterns to match multiple groups.  This has same
> +effect that repeating -e option and -G option for each event x name.  This option
> +cannot be used with -G/--cgroup option.
>  
>  -o file::
>  --output file::
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index b01af171d94f..6709578128c9 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -2235,8 +2235,11 @@ int cmd_stat(int argc, const char **argv)
>  		}
>  
>  		if (evlist__expand_cgroup(evsel_list, stat_config.cgroup_list,
> -					  &stat_config.metric_events, true) < 0)
> +					  &stat_config.metric_events, true) < 0) {
> +			parse_options_usage(stat_usage, stat_options,
> +					    "for-each-cgroup", 0);
>  			goto out;
> +		}
>  	}
>  
>  	target__validate(&target);
> diff --git a/tools/perf/util/cgroup.c b/tools/perf/util/cgroup.c
> index b81324a13a2b..704333748549 100644
> --- a/tools/perf/util/cgroup.c
> +++ b/tools/perf/util/cgroup.c
> @@ -13,9 +13,19 @@
>  #include <stdlib.h>
>  #include <string.h>
>  #include <api/fs/fs.h>
> +#include <ftw.h>
> +#include <regex.h>
>  
>  int nr_cgroups;
>  
> +/* used to match cgroup name with patterns */
> +struct cgroup_name {
> +	struct list_head list;
> +	bool used;
> +	char name[];
> +};
> +static LIST_HEAD(cgroup_list);
> +
>  static int open_cgroup(const char *name)
>  {
>  	char path[PATH_MAX + 1];
> @@ -149,6 +159,137 @@ void evlist__set_default_cgroup(struct evlist *evlist, struct cgroup *cgroup)
>  		evsel__set_default_cgroup(evsel, cgroup);
>  }
>  
> +/* helper function for ftw() in match_cgroups and list_cgroups */
> +static int add_cgroup_name(const char *fpath, const struct stat *sb __maybe_unused,
> +			   int typeflag)
> +{
> +	struct cgroup_name *cn;
> +
> +	if (typeflag != FTW_D)
> +		return 0;
> +
> +	cn = malloc(sizeof(*cn) + strlen(fpath) + 1);
> +	if (cn == NULL)
> +		return -1;
> +
> +	cn->used = false;
> +	strcpy(cn->name, fpath);
> +
> +	list_add_tail(&cn->list, &cgroup_list);
> +	return 0;
> +}
> +
> +static void release_cgroup_list(void)
> +{
> +	struct cgroup_name *cn;
> +
> +	while (!list_empty(&cgroup_list)) {
> +		cn = list_first_entry(&cgroup_list, struct cgroup_name, list);
> +		list_del(&cn->list);
> +		free(cn);
> +	}
> +}
> +
> +/* collect given cgroups only */
> +static int list_cgroups(const char *str)
> +{
> +	const char *p, *e, *eos = str + strlen(str);
> +	struct cgroup_name *cn;
> +	char *s;
> +
> +	/* use given name as is - for testing purpose */
> +	for (;;) {
> +		p = strchr(str, ',');
> +		e = p ? p : eos;
> +
> +		if (e - str) {
> +			int ret;
> +
> +			s = strndup(str, e - str);
> +			if (!s)
> +				return -1;
> +			/* pretend if it's added by ftw() */
> +			ret = add_cgroup_name(s, NULL, FTW_D);
> +			free(s);
> +			if (ret)
> +				return -1;
> +		} else {
> +			if (add_cgroup_name("", NULL, FTW_D) < 0)
> +				return -1;
> +		}
> +
> +		if (!p)
> +			break;
> +		str = p+1;
> +	}
> +
> +	/* these groups will be used */
> +	list_for_each_entry(cn, &cgroup_list, list)
> +		cn->used = true;
> +
> +	return 0;
> +}
> +
> +/* collect all cgroups first and then match with the pattern */
> +static int match_cgroups(const char *str)
> +{
> +	char mnt[PATH_MAX];
> +	const char *p, *e, *eos = str + strlen(str);
> +	struct cgroup_name *cn;
> +	regex_t reg;
> +	int prefix_len;
> +	char *s;
> +
> +	if (cgroupfs_find_mountpoint(mnt, sizeof(mnt), "perf_event"))
> +		return -1;
> +
> +	/* cgroup_name will have a full path, skip the root directory */
> +	prefix_len = strlen(mnt);
> +
> +	/* collect all cgroups in the cgroup_list */
> +	if (ftw(mnt, add_cgroup_name, 20) < 0)
> +		return -1;
> +
> +	for (;;) {
> +		p = strchr(str, ',');
> +		e = p ? p : eos;
> +
> +		/* allow empty cgroups, i.e., skip */
> +		if (e - str) {
> +			/* termination added */
> +			s = strndup(str, e - str);
> +			if (!s)
> +				return -1;
> +			if (regcomp(&reg, s, REG_NOSUB)) {
> +				free(s);
> +				return -1;
> +			}
> +
> +			/* check cgroup name with the pattern */
> +			list_for_each_entry(cn, &cgroup_list, list) {
> +				char *name = cn->name + prefix_len;
> +
> +				if (name[0] == '/' && name[1])
> +					name++;
> +				if (!regexec(&reg, name, 0, NULL, 0))
> +					cn->used = true;
> +			}
> +			regfree(&reg);
> +			free(s);
> +		} else {
> +			/* first entry to root cgroup */
> +			cn = list_first_entry(&cgroup_list, struct cgroup_name,
> +					      list);
> +			cn->used = true;
> +		}
> +
> +		if (!p)
> +			break;
> +		str = p+1;
> +	}
> +	return prefix_len;
> +}
> +
>  int parse_cgroups(const struct option *opt, const char *str,
>  		  int unset __maybe_unused)
>  {
> @@ -201,6 +342,11 @@ int parse_cgroups(const struct option *opt, const char *str,
>  	return 0;
>  }
>  
> +static bool has_pattern_string(const char *str)
> +{
> +	return !!strpbrk(str, "{}[]()|*+?^$");
> +}
> +
>  int evlist__expand_cgroup(struct evlist *evlist, const char *str,
>  			  struct rblist *metric_events, bool open_cgroup)
>  {
> @@ -208,8 +354,9 @@ int evlist__expand_cgroup(struct evlist *evlist, const char *str,
>  	struct evsel *pos, *evsel, *leader;
>  	struct rblist orig_metric_events;
>  	struct cgroup *cgrp = NULL;
> -	const char *p, *e, *eos = str + strlen(str);
> +	struct cgroup_name *cn;
>  	int ret = -1;
> +	int prefix_len;
>  
>  	if (evlist->core.nr_entries == 0) {
>  		fprintf(stderr, "must define events before cgroups\n");
> @@ -234,24 +381,27 @@ int evlist__expand_cgroup(struct evlist *evlist, const char *str,
>  		rblist__init(&orig_metric_events);
>  	}
>  
> -	for (;;) {
> -		p = strchr(str, ',');
> -		e = p ? p : eos;
> +	if (has_pattern_string(str))
> +		prefix_len = match_cgroups(str);
> +	else
> +		prefix_len = list_cgroups(str);
>  
> -		/* allow empty cgroups, i.e., skip */
> -		if (e - str) {
> -			/* termination added */
> -			char *name = strndup(str, e - str);
> -			if (!name)
> -				goto out_err;
> +	if (prefix_len < 0)
> +		goto out_err;
>  
> -			cgrp = cgroup__new(name, open_cgroup);
> -			free(name);
> -			if (cgrp == NULL)
> -				goto out_err;
> -		} else {
> -			cgrp = NULL;
> -		}
> +	list_for_each_entry(cn, &cgroup_list, list) {
> +		char *name;
> +
> +		if (!cn->used)
> +			continue;
> +
> +		/* cgroup_name might have a full path, skip the prefix */
> +		name = cn->name + prefix_len;
> +		if (name[0] == '/' && name[1])
> +			name++;
> +		cgrp = cgroup__new(name, open_cgroup);
> +		if (cgrp == NULL)
> +			goto out_err;
>  
>  		leader = NULL;
>  		evlist__for_each_entry(orig_list, pos) {
> @@ -277,23 +427,25 @@ int evlist__expand_cgroup(struct evlist *evlist, const char *str,
>  			if (metricgroup__copy_metric_events(tmp_list, cgrp,
>  							    metric_events,
>  							    &orig_metric_events) < 0)
> -				break;
> +				goto out_err;
>  		}
>  
>  		perf_evlist__splice_list_tail(evlist, &tmp_list->core.entries);
>  		tmp_list->core.nr_entries = 0;
> +	}
>  
> -		if (!p) {
> -			ret = 0;
> -			break;
> -		}
> -		str = p+1;
> +	if (list_empty(&evlist->core.entries)) {
> +		fprintf(stderr, "no cgroup matched: %s\n", str);
> +		goto out_err;
>  	}
>  
> +	ret = 0;
> +
>  out_err:
>  	evlist__delete(orig_list);
>  	evlist__delete(tmp_list);
>  	rblist__exit(&orig_metric_events);
> +	release_cgroup_list();
>  
>  	return ret;
>  }
> -- 
> 2.29.0.rc2.309.g374f81d7ae-goog
>