Commit 5e3febe7 authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
Browse files

perf lock contention: Support lock addr/name filtering for BPF 



Likewise, add addr_filter BPF hash map and check it with the lock
address.

  $ sudo ./perf lock con -ab -L tasklist_lock -- ./perf bench sched messaging
  # Running 'sched/messaging' benchmark:
  # 20 sender and receiver processes per group
  # 10 groups == 400 processes run

       Total time: 0.169 [sec]
   contended  total wait  max wait  avg wait      type  caller

          18   174.09 us  25.31 us   9.67 us  rwlock:W  do_exit+0x36d
           5    32.34 us  10.87 us   6.47 us  rwlock:R  do_wait+0x8b
           4    15.41 us   4.73 us   3.85 us  rwlock:W  release_task+0x6e

Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Blake Jones <blakejones@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20221219201732.460111-6-namhyung@kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 511e19b9

tools/perf/util/bpf_lock_contention.c

+41 −1
Original line number Diff line number Diff line
@@ -20,7 +20,7 @@ static struct lock_contention_bpf *skel; 
int lock_contention_prepare(struct lock_contention *con)

{

	int i, fd;

	int ncpus = 1, ntasks = 1, ntypes = 1;

	int ncpus = 1, ntasks = 1, ntypes = 1, naddrs = 1;

	struct evlist *evlist = con->evlist;

	struct target *target = con->target;
@@ -49,9 +49,39 @@ int lock_contention_prepare(struct lock_contention *con) 
	if (con->filters->nr_types)

		ntypes = con->filters->nr_types;



	/* resolve lock name filters to addr */

	if (con->filters->nr_syms) {

		struct symbol *sym;

		struct map *kmap;

		unsigned long *addrs;



		for (i = 0; i < con->filters->nr_syms; i++) {

			sym = machine__find_kernel_symbol_by_name(con->machine,

								  con->filters->syms[i],

								  &kmap);

			if (sym == NULL) {

				pr_warning("ignore unknown symbol: %s\n",

					   con->filters->syms[i]);

				continue;

			}



			addrs = realloc(con->filters->addrs,

					(con->filters->nr_addrs + 1) * sizeof(*addrs));

			if (addrs == NULL) {

				pr_warning("memory allocation failure\n");

				continue;

			}



			addrs[con->filters->nr_addrs++] = kmap->unmap_ip(kmap, sym->start);

			con->filters->addrs = addrs;

		}

		naddrs = con->filters->nr_addrs;

	}



	bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus);

	bpf_map__set_max_entries(skel->maps.task_filter, ntasks);

	bpf_map__set_max_entries(skel->maps.type_filter, ntypes);

	bpf_map__set_max_entries(skel->maps.addr_filter, naddrs);



	if (lock_contention_bpf__load(skel) < 0) {

		pr_err("Failed to load lock-contention BPF skeleton\n");
@@ -103,6 +133,16 @@ int lock_contention_prepare(struct lock_contention *con) 
			bpf_map_update_elem(fd, &con->filters->types[i], &val, BPF_ANY);

	}



	if (con->filters->nr_addrs) {

		u8 val = 1;



		skel->bss->has_addr = 1;

		fd = bpf_map__fd(skel->maps.addr_filter);



		for (i = 0; i < con->filters->nr_addrs; i++)

			bpf_map_update_elem(fd, &con->filters->addrs[i], &val, BPF_ANY);

	}



	/* these don't work well if in the rodata section */

	skel->bss->stack_skip = con->stack_skip;

	skel->bss->aggr_mode = con->aggr_mode;

tools/perf/util/bpf_skel/lock_contention.bpf.c

+17 −0
Original line number Diff line number Diff line
@@ -69,11 +69,19 @@ struct { 
	__uint(max_entries, 1);

} type_filter SEC(".maps");



struct {

	__uint(type, BPF_MAP_TYPE_HASH);

	__uint(key_size, sizeof(__u64));

	__uint(value_size, sizeof(__u8));

	__uint(max_entries, 1);

} addr_filter SEC(".maps");



/* control flags */

int enabled;

int has_cpu;

int has_task;

int has_type;

int has_addr;

int stack_skip;



/* determine the key of lock stat */
@@ -111,6 +119,15 @@ static inline int can_record(u64 *ctx) 
			return 0;

	}



	if (has_addr) {

		__u8 *ok;

		__u64 addr = ctx[0];



		ok = bpf_map_lookup_elem(&addr_filter, &addr);

		if (!ok)

			return 0;

	}



	return 1;

}