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Date: Wed, 1 Feb 2023 22:31:28 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Jiri Olsa <jolsa@...nel.org>, Ingo Molnar <mingo@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
LKML <linux-kernel@...r.kernel.org>,
Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
linux-perf-users@...r.kernel.org, Song Liu <song@...nel.org>,
bpf@...r.kernel.org
Subject: Re: [PATCH] perf lock contention: Add -S/--callstack-filter option
Em Wed, Jan 25, 2023 at 04:09:36PM -0800, Namhyung Kim escreveu:
> The -S/--callstack-filter is to limit display entries having the given
> string in the callstack (not only in the caller in the output).
>
> The following example shows lock contention results if the callstack
> has 'net' substring somewhere. Note that the caller '__dev_queue_xmit'
> does not match to it, but it has 'inet6_csk_xmit' in the callstack.
Looks useful!
Thanks, applied.
- Arnaldo
> This applies even if you don't use -v option to show the full callstack.
>
> $ sudo ./perf lock con -abv -S net sleep 1
> ...
> contended total wait max wait avg wait type caller
>
> 5 70.20 us 16.13 us 14.04 us spinlock __dev_queue_xmit+0xb6d
> 0xffffffffa5dd1c60 _raw_spin_lock+0x30
> 0xffffffffa5b8f6ed __dev_queue_xmit+0xb6d
> 0xffffffffa5cd8267 ip6_finish_output2+0x2c7
> 0xffffffffa5cdac14 ip6_finish_output+0x1d4
> 0xffffffffa5cdb477 ip6_xmit+0x457
> 0xffffffffa5d1fd17 inet6_csk_xmit+0xd7
> 0xffffffffa5c5f4aa __tcp_transmit_skb+0x54a
> 0xffffffffa5c6467d tcp_keepalive_timer+0x2fd
>
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
> tools/perf/Documentation/perf-lock.txt | 6 +++
> tools/perf/builtin-lock.c | 68 +++++++++++++++++++++++++-
> tools/perf/util/bpf_lock_contention.c | 2 +-
> tools/perf/util/lock-contention.h | 1 +
> 4 files changed, 75 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/Documentation/perf-lock.txt b/tools/perf/Documentation/perf-lock.txt
> index 0f9f720e599d..11b8901d8d13 100644
> --- a/tools/perf/Documentation/perf-lock.txt
> +++ b/tools/perf/Documentation/perf-lock.txt
> @@ -187,6 +187,12 @@ CONTENTION OPTIONS
> --lock-filter=<value>::
> Show lock contention only for given lock addresses or names (comma separated list).
>
> +-S::
> +--callstack-filter=<value>::
> + Show lock contention only if the callstack contains the given string.
> + Note that it matches the substring so 'rq' would match both 'raw_spin_rq_lock'
> + and 'irq_enter_rcu'.
> +
>
> SEE ALSO
> --------
> diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
> index 506c2fe42d52..216a9a252bf4 100644
> --- a/tools/perf/builtin-lock.c
> +++ b/tools/perf/builtin-lock.c
> @@ -63,11 +63,22 @@ static unsigned long bpf_map_entries = 10240;
> static int max_stack_depth = CONTENTION_STACK_DEPTH;
> static int stack_skip = CONTENTION_STACK_SKIP;
> static int print_nr_entries = INT_MAX / 2;
> +static LIST_HEAD(callstack_filters);
> +
> +struct callstack_filter {
> + struct list_head list;
> + char name[];
> +};
>
> static struct lock_filter filters;
>
> static enum lock_aggr_mode aggr_mode = LOCK_AGGR_ADDR;
>
> +static bool needs_callstack(void)
> +{
> + return verbose > 0 || !list_empty(&callstack_filters);
> +}
> +
> static struct thread_stat *thread_stat_find(u32 tid)
> {
> struct rb_node *node;
> @@ -1060,7 +1071,7 @@ static int report_lock_contention_begin_event(struct evsel *evsel,
> if (!ls)
> return -ENOMEM;
>
> - if (aggr_mode == LOCK_AGGR_CALLER && verbose > 0) {
> + if (aggr_mode == LOCK_AGGR_CALLER && needs_callstack()) {
> ls->callstack = get_callstack(sample, max_stack_depth);
> if (ls->callstack == NULL)
> return -ENOMEM;
> @@ -1595,6 +1606,31 @@ static void print_contention_result(struct lock_contention *con)
> if (!st->wait_time_total)
> continue;
>
> + if (aggr_mode == LOCK_AGGR_CALLER && !list_empty(&callstack_filters)) {
> + struct map *kmap;
> + struct symbol *sym;
> + u64 ip;
> +
> + for (int i = 0; i < max_stack_depth; i++) {
> + struct callstack_filter *filter;
> +
> + if (!st->callstack || !st->callstack[i])
> + break;
> +
> + ip = st->callstack[i];
> + sym = machine__find_kernel_symbol(con->machine, ip, &kmap);
> + if (sym == NULL)
> + continue;
> +
> + list_for_each_entry(filter, &callstack_filters, list) {
> + if (strstr(sym->name, filter->name))
> + goto found;
> + }
> + }
> + continue;
> + }
> +
> +found:
> list_for_each_entry(key, &lock_keys, list) {
> key->print(key, st);
> pr_info(" ");
> @@ -1743,6 +1779,7 @@ static int __cmd_contention(int argc, const char **argv)
> .max_stack = max_stack_depth,
> .stack_skip = stack_skip,
> .filters = &filters,
> + .save_callstack = needs_callstack(),
> };
>
> session = perf_session__new(use_bpf ? NULL : &data, &eops);
> @@ -2123,6 +2160,33 @@ static int parse_lock_addr(const struct option *opt __maybe_unused, const char *
> return ret;
> }
>
> +static int parse_call_stack(const struct option *opt __maybe_unused, const char *str,
> + int unset __maybe_unused)
> +{
> + char *s, *tmp, *tok;
> + int ret = 0;
> +
> + s = strdup(str);
> + if (s == NULL)
> + return -1;
> +
> + for (tok = strtok_r(s, ", ", &tmp); tok; tok = strtok_r(NULL, ", ", &tmp)) {
> + struct callstack_filter *entry;
> +
> + entry = malloc(sizeof(*entry) + strlen(tok) + 1);
> + if (entry == NULL) {
> + pr_err("Memory allocation failure\n");
> + return -1;
> + }
> +
> + strcpy(entry->name, tok);
> + list_add_tail(&entry->list, &callstack_filters);
> + }
> +
> + free(s);
> + return ret;
> +}
> +
> int cmd_lock(int argc, const char **argv)
> {
> const struct option lock_options[] = {
> @@ -2190,6 +2254,8 @@ int cmd_lock(int argc, const char **argv)
> "Filter specific type of locks", parse_lock_type),
> OPT_CALLBACK('L', "lock-filter", NULL, "ADDRS/NAMES",
> "Filter specific address/symbol of locks", parse_lock_addr),
> + OPT_CALLBACK('S', "callstack-filter", NULL, "NAMES",
> + "Filter specific function in the callstack", parse_call_stack),
> OPT_PARENT(lock_options)
> };
>
> diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
> index 0236334fd69b..4902ac331f41 100644
> --- a/tools/perf/util/bpf_lock_contention.c
> +++ b/tools/perf/util/bpf_lock_contention.c
> @@ -268,7 +268,7 @@ int lock_contention_read(struct lock_contention *con)
> break;
> }
>
> - if (verbose > 0) {
> + if (con->save_callstack) {
> st->callstack = memdup(stack_trace, stack_size);
> if (st->callstack == NULL)
> break;
> diff --git a/tools/perf/util/lock-contention.h b/tools/perf/util/lock-contention.h
> index b99e83fccf5c..17e594d57a61 100644
> --- a/tools/perf/util/lock-contention.h
> +++ b/tools/perf/util/lock-contention.h
> @@ -128,6 +128,7 @@ struct lock_contention {
> int max_stack;
> int stack_skip;
> int aggr_mode;
> + bool save_callstack;
> };
>
> #ifdef HAVE_BPF_SKEL
> --
> 2.39.1.456.gfc5497dd1b-goog
>
--
- Arnaldo
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