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Message-ID: <ZPjTB3tj+/b90+BF@kernel.org>
Date:   Wed, 6 Sep 2023 16:29:11 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-perf-users@...r.kernel.org, Song Liu <song@...nel.org>,
        Hao Luo <haoluo@...gle.com>, bpf@...r.kernel.org
Subject: Re: [PATCH 3/5] perf lock contention: Add -g/--lock-cgroup option

Em Wed, Sep 06, 2023 at 04:23:17PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Wed, Sep 06, 2023 at 10:49:01AM -0700, Namhyung Kim escreveu:
> > The -g option shows lock contention stats break down by cgroups.
> > Add LOCK_AGGR_CGROUP mode and use it instead of use_cgroup field.
> > 
> >   $ sudo ./perf lock con -abg sleep 1
> >    contended   total wait     max wait     avg wait   cgroup
> > 
> >            8     15.70 us      6.34 us      1.96 us   /
> >            2      1.48 us       747 ns       738 ns   /user.slice/.../app.slice/app-gnome-google\x2dchrome-6442.scope
> >            1       848 ns       848 ns       848 ns   /user.slice/.../session.slice/org.gnome.Shell@....service
> >            1       220 ns       220 ns       220 ns   /user.slice/.../session.slice/pipewire-pulse.service
> > 
> > For now, the cgroup mode only works with BPF (-b).
> 
> Can we try to be consistent with other tools?
> 
> [root@...co ~]# perf record -h -g
> 
>  Usage: perf record [<options>] [<command>]
>     or: perf record [<options>] -- <command> [<options>]
> 
>     -g                    enables call-graph recording
> 
> [root@...co ~]# perf record -h -G
> 
>  Usage: perf record [<options>] [<command>]
>     or: perf record [<options>] -- <command> [<options>]
> 
>     -G, --cgroup <name>   monitor event in cgroup name only
> 
> [root@...co ~]# set -o vi
> [root@...co ~]# perf lock contention -h -G
> 
>  Usage: perf lock contention [<options>]
> 
> 
> [root@...co ~]#
> 
> I.e. use -G in this patch?
> 
> If you agree I can fixup things here, otherwise why not?

I see that you use -G in 4/5, unsure now, but this looks like --sort in
'perf report', no?

- Arnaldo
 
> - Arnaldo
>  
> > Reviewed-by: Ian Rogers <irogers@...gle.com>
> > Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> > ---
> >  tools/perf/Documentation/perf-lock.txt        |  4 ++
> >  tools/perf/builtin-lock.c                     | 40 ++++++++++++++++++-
> >  tools/perf/util/bpf_lock_contention.c         | 16 +++++---
> >  .../perf/util/bpf_skel/lock_contention.bpf.c  | 31 +++++++++++++-
> >  tools/perf/util/bpf_skel/lock_data.h          |  3 +-
> >  tools/perf/util/lock-contention.h             |  1 -
> >  6 files changed, 85 insertions(+), 10 deletions(-)
> > 
> > diff --git a/tools/perf/Documentation/perf-lock.txt b/tools/perf/Documentation/perf-lock.txt
> > index 30eea576721f..61c491df72b8 100644
> > --- a/tools/perf/Documentation/perf-lock.txt
> > +++ b/tools/perf/Documentation/perf-lock.txt
> > @@ -208,6 +208,10 @@ CONTENTION OPTIONS
> >  	Show results using a CSV-style output to make it easy to import directly
> >  	into spreadsheets. Columns are separated by the string specified in SEP.
> >  
> > +-g::
> > +--lock-cgroup::
> > +	Show lock contention stat by cgroup.  Requires --use-bpf.
> > +
> >  
> >  SEE ALSO
> >  --------
> > diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
> > index 06430980dfd7..b98948dd40ba 100644
> > --- a/tools/perf/builtin-lock.c
> > +++ b/tools/perf/builtin-lock.c
> > @@ -60,6 +60,7 @@ static bool combine_locks;
> >  static bool show_thread_stats;
> >  static bool show_lock_addrs;
> >  static bool show_lock_owner;
> > +static bool show_lock_cgroups;
> >  static bool use_bpf;
> >  static unsigned long bpf_map_entries = MAX_ENTRIES;
> >  static int max_stack_depth = CONTENTION_STACK_DEPTH;
> > @@ -619,6 +620,7 @@ static int get_key_by_aggr_mode_simple(u64 *key, u64 addr, u32 tid)
> >  		*key = tid;
> >  		break;
> >  	case LOCK_AGGR_CALLER:
> > +	case LOCK_AGGR_CGROUP:
> >  	default:
> >  		pr_err("Invalid aggregation mode: %d\n", aggr_mode);
> >  		return -EINVAL;
> > @@ -1103,6 +1105,7 @@ static int report_lock_contention_begin_event(struct evsel *evsel,
> >  			if (lock_contention_caller(evsel, sample, buf, sizeof(buf)) < 0)
> >  				name = "Unknown";
> >  			break;
> > +		case LOCK_AGGR_CGROUP:
> >  		case LOCK_AGGR_TASK:
> >  		default:
> >  			break;
> > @@ -1653,6 +1656,9 @@ static void print_header_stdio(void)
> >  	case LOCK_AGGR_ADDR:
> >  		fprintf(lock_output, "  %16s   %s\n\n", "address", "symbol");
> >  		break;
> > +	case LOCK_AGGR_CGROUP:
> > +		fprintf(lock_output, "  %s\n\n", "cgroup");
> > +		break;
> >  	default:
> >  		break;
> >  	}
> > @@ -1680,6 +1686,9 @@ static void print_header_csv(const char *sep)
> >  	case LOCK_AGGR_ADDR:
> >  		fprintf(lock_output, "%s%s %s%s %s\n", "address", sep, "symbol", sep, "type");
> >  		break;
> > +	case LOCK_AGGR_CGROUP:
> > +		fprintf(lock_output, "%s\n", "cgroup");
> > +		break;
> >  	default:
> >  		break;
> >  	}
> > @@ -1720,6 +1729,9 @@ static void print_lock_stat_stdio(struct lock_contention *con, struct lock_stat
> >  		fprintf(lock_output, "  %016llx   %s (%s)\n", (unsigned long long)st->addr,
> >  			st->name, get_type_name(st->flags));
> >  		break;
> > +	case LOCK_AGGR_CGROUP:
> > +		fprintf(lock_output, "  %s\n", st->name);
> > +		break;
> >  	default:
> >  		break;
> >  	}
> > @@ -1770,6 +1782,9 @@ static void print_lock_stat_csv(struct lock_contention *con, struct lock_stat *s
> >  		fprintf(lock_output, "%llx%s %s%s %s\n", (unsigned long long)st->addr, sep,
> >  			st->name, sep, get_type_name(st->flags));
> >  		break;
> > +	case LOCK_AGGR_CGROUP:
> > +		fprintf(lock_output, "%s\n",st->name);
> > +		break;
> >  	default:
> >  		break;
> >  	}
> > @@ -1999,6 +2014,27 @@ static int check_lock_contention_options(const struct option *options,
> >  		return -1;
> >  	}
> >  
> > +	if (show_lock_cgroups && !use_bpf) {
> > +		pr_err("Cgroups are available only with BPF\n");
> > +		parse_options_usage(usage, options, "lock-cgroup", 0);
> > +		parse_options_usage(NULL, options, "use-bpf", 0);
> > +		return -1;
> > +	}
> > +
> > +	if (show_lock_cgroups && show_lock_addrs) {
> > +		pr_err("Cannot use cgroup and addr mode together\n");
> > +		parse_options_usage(usage, options, "lock-cgroup", 0);
> > +		parse_options_usage(NULL, options, "lock-addr", 0);
> > +		return -1;
> > +	}
> > +
> > +	if (show_lock_cgroups && show_thread_stats) {
> > +		pr_err("Cannot use cgroup and thread mode together\n");
> > +		parse_options_usage(usage, options, "lock-cgroup", 0);
> > +		parse_options_usage(NULL, options, "threads", 0);
> > +		return -1;
> > +	}
> > +
> >  	if (symbol_conf.field_sep) {
> >  		if (strstr(symbol_conf.field_sep, ":") || /* part of type flags */
> >  		    strstr(symbol_conf.field_sep, "+") || /* part of caller offset */
> > @@ -2060,7 +2096,8 @@ static int __cmd_contention(int argc, const char **argv)
> >  	con.machine = &session->machines.host;
> >  
> >  	con.aggr_mode = aggr_mode = show_thread_stats ? LOCK_AGGR_TASK :
> > -		show_lock_addrs ? LOCK_AGGR_ADDR : LOCK_AGGR_CALLER;
> > +		show_lock_addrs ? LOCK_AGGR_ADDR :
> > +		show_lock_cgroups ? LOCK_AGGR_CGROUP : LOCK_AGGR_CALLER;
> >  
> >  	if (con.aggr_mode == LOCK_AGGR_CALLER)
> >  		con.save_callstack = true;
> > @@ -2524,6 +2561,7 @@ int cmd_lock(int argc, const char **argv)
> >  	OPT_BOOLEAN('o', "lock-owner", &show_lock_owner, "show lock owners instead of waiters"),
> >  	OPT_STRING_NOEMPTY('x', "field-separator", &symbol_conf.field_sep, "separator",
> >  		   "print result in CSV format with custom separator"),
> > +	OPT_BOOLEAN('g', "lock-cgroup", &show_lock_cgroups, "show lock stats by cgroup"),
> >  	OPT_PARENT(lock_options)
> >  	};
> >  
> > diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
> > index c6bd7c9b2d57..42753a0dfdc5 100644
> > --- a/tools/perf/util/bpf_lock_contention.c
> > +++ b/tools/perf/util/bpf_lock_contention.c
> > @@ -152,7 +152,10 @@ int lock_contention_prepare(struct lock_contention *con)
> >  	skel->bss->needs_callstack = con->save_callstack;
> >  	skel->bss->lock_owner = con->owner;
> >  
> > -	if (con->use_cgroup) {
> > +	if (con->aggr_mode == LOCK_AGGR_CGROUP) {
> > +		if (cgroup_is_v2("perf_event"))
> > +			skel->bss->use_cgroup_v2 = 1;
> > +
> >  		read_all_cgroups(&con->cgroups);
> >  	}
> >  
> > @@ -214,12 +217,12 @@ static const char *lock_contention_get_name(struct lock_contention *con,
> >  			return "siglock";
> >  
> >  		/* global locks with symbols */
> > -		sym = machine__find_kernel_symbol(machine, key->lock_addr, &kmap);
> > +		sym = machine__find_kernel_symbol(machine, key->lock_addr_or_cgroup, &kmap);
> >  		if (sym)
> >  			return sym->name;
> >  
> >  		/* try semi-global locks collected separately */
> > -		if (!bpf_map_lookup_elem(lock_fd, &key->lock_addr, &flags)) {
> > +		if (!bpf_map_lookup_elem(lock_fd, &key->lock_addr_or_cgroup, &flags)) {
> >  			if (flags == LOCK_CLASS_RQLOCK)
> >  				return "rq_lock";
> >  		}
> > @@ -227,8 +230,8 @@ static const char *lock_contention_get_name(struct lock_contention *con,
> >  		return "";
> >  	}
> >  
> > -	if (con->use_cgroup) {
> > -		u64 cgrp_id = key->lock_addr;
> > +	if (con->aggr_mode == LOCK_AGGR_CGROUP) {
> > +		u64 cgrp_id = key->lock_addr_or_cgroup;
> >  		struct cgroup *cgrp = __cgroup__find(&con->cgroups, cgrp_id);
> >  
> >  		if (cgrp)
> > @@ -329,7 +332,8 @@ int lock_contention_read(struct lock_contention *con)
> >  			ls_key = key.pid;
> >  			break;
> >  		case LOCK_AGGR_ADDR:
> > -			ls_key = key.lock_addr;
> > +		case LOCK_AGGR_CGROUP:
> > +			ls_key = key.lock_addr_or_cgroup;
> >  			break;
> >  		default:
> >  			goto next;
> > diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > index 8d3cfbb3cc65..823354999022 100644
> > --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > @@ -118,6 +118,9 @@ int needs_callstack;
> >  int stack_skip;
> >  int lock_owner;
> >  
> > +int use_cgroup_v2;
> > +int perf_subsys_id = -1;
> > +
> >  /* determine the key of lock stat */
> >  int aggr_mode;
> >  
> > @@ -130,6 +133,29 @@ int data_fail;
> >  int task_map_full;
> >  int data_map_full;
> >  
> > +static inline __u64 get_current_cgroup_id(void)
> > +{
> > +	struct task_struct *task;
> > +	struct cgroup *cgrp;
> > +
> > +	if (use_cgroup_v2)
> > +		return bpf_get_current_cgroup_id();
> > +
> > +	task = bpf_get_current_task_btf();
> > +
> > +	if (perf_subsys_id == -1) {
> > +#if __has_builtin(__builtin_preserve_enum_value)
> > +		perf_subsys_id = bpf_core_enum_value(enum cgroup_subsys_id,
> > +						     perf_event_cgrp_id);
> > +#else
> > +		perf_subsys_id = perf_event_cgrp_id;
> > +#endif
> > +	}
> > +
> > +	cgrp = BPF_CORE_READ(task, cgroups, subsys[perf_subsys_id], cgroup);
> > +	return BPF_CORE_READ(cgrp, kn, id);
> > +}
> > +
> >  static inline int can_record(u64 *ctx)
> >  {
> >  	if (has_cpu) {
> > @@ -364,10 +390,13 @@ int contention_end(u64 *ctx)
> >  			key.stack_id = pelem->stack_id;
> >  		break;
> >  	case LOCK_AGGR_ADDR:
> > -		key.lock_addr = pelem->lock;
> > +		key.lock_addr_or_cgroup = pelem->lock;
> >  		if (needs_callstack)
> >  			key.stack_id = pelem->stack_id;
> >  		break;
> > +	case LOCK_AGGR_CGROUP:
> > +		key.lock_addr_or_cgroup = get_current_cgroup_id();
> > +		break;
> >  	default:
> >  		/* should not happen */
> >  		return 0;
> > diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h
> > index 260062a9f2ab..08482daf61be 100644
> > --- a/tools/perf/util/bpf_skel/lock_data.h
> > +++ b/tools/perf/util/bpf_skel/lock_data.h
> > @@ -6,7 +6,7 @@
> >  struct contention_key {
> >  	u32 stack_id;
> >  	u32 pid;
> > -	u64 lock_addr;
> > +	u64 lock_addr_or_cgroup;
> >  };
> >  
> >  #define TASK_COMM_LEN  16
> > @@ -39,6 +39,7 @@ enum lock_aggr_mode {
> >  	LOCK_AGGR_ADDR = 0,
> >  	LOCK_AGGR_TASK,
> >  	LOCK_AGGR_CALLER,
> > +	LOCK_AGGR_CGROUP,
> >  };
> >  
> >  enum lock_class_sym {
> > diff --git a/tools/perf/util/lock-contention.h b/tools/perf/util/lock-contention.h
> > index 70423966d778..a073cc6a82d2 100644
> > --- a/tools/perf/util/lock-contention.h
> > +++ b/tools/perf/util/lock-contention.h
> > @@ -144,7 +144,6 @@ struct lock_contention {
> >  	int owner;
> >  	int nr_filtered;
> >  	bool save_callstack;
> > -	bool use_cgroup;
> >  };
> >  
> >  #ifdef HAVE_BPF_SKEL
> > -- 
> > 2.42.0.283.g2d96d420d3-goog
> > 
> 
> -- 
> 
> - Arnaldo

-- 

- Arnaldo

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