Re: [PATCH 3/5] perf lock contention: Add -g/--lock-cgroup option

From: Arnaldo Carvalho de Melo
Date: Wed Sep 06 2023 - 15:23:28 EST

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In reply to: Namhyung Kim: "[PATCH 3/5] perf lock contention: Add -g/--lock-cgroup option"
Next in thread: Arnaldo Carvalho de Melo: "Re: [PATCH 3/5] perf lock contention: Add -g/--lock-cgroup option"
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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@x11.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@quaco ~]# perf record -h -g

Usage: perf record [<options>] [<command>]
or: perf record [<options>] -- <command> [<options>]

-g enables call-graph recording

[root@quaco ~]# 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@quaco ~]# set -o vi
[root@quaco ~]# perf lock contention -h -G

Usage: perf lock contention [<options>]

[root@quaco ~]#

I.e. use -G in this patch?

If you agree I can fixup things here, otherwise why not?

- Arnaldo

> Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>
> Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
> ---
> 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

Next message: Lorenzo Stoakes: "Re: [PATCH v3 1/2] mm/vmalloc: Add a safer version of find_vm_area() for debug"
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In reply to: Namhyung Kim: "[PATCH 3/5] perf lock contention: Add -g/--lock-cgroup option"
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