From: Tao Chen <chen.dylane@linux.dev>
To: Jiri Olsa <olsajiri@gmail.com>
Cc: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com,
andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com,
song@kernel.org, yonghong.song@linux.dev, kpsingh@kernel.org,
sdf@fomichev.me, haoluo@google.com, bpf@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf-next 2/2] selftests/bpf: Add stacktrace map lookup_and_delete_elem test case
Date: Tue, 9 Sep 2025 21:07:48 +0800 [thread overview]
Message-ID: <eae6de3a-284c-40f4-bdfa-ca4b98bf55e1@linux.dev> (raw)
In-Reply-To: <aMAfAf1JEAcbYOuq@krava>
在 2025/9/9 20:35, Jiri Olsa 写道:
> On Mon, Sep 08, 2025 at 07:36:22PM +0800, Tao Chen wrote:
>> ...
>> test_stacktrace_map:PASS:compare_stack_ips stackmap vs. stack_amap 0 nsec
>> test_stacktrace_map:PASS:stack_key_map lookup 0 nsec
>> test_stacktrace_map:PASS:stackmap lookup and detele 0 nsec
>> #397 stacktrace_map:OK
>> ...
>>
>> Signed-off-by: Tao Chen <chen.dylane@linux.dev>
>> ---
>> .../selftests/bpf/prog_tests/stacktrace_map.c | 18 +++++++++++++++++-
>> .../selftests/bpf/progs/test_stacktrace_map.c | 12 +++++++++++-
>> 2 files changed, 28 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/testing/selftests/bpf/prog_tests/stacktrace_map.c b/tools/testing/selftests/bpf/prog_tests/stacktrace_map.c
>> index 84a7e405e91..496c4dcf4ea 100644
>> --- a/tools/testing/selftests/bpf/prog_tests/stacktrace_map.c
>> +++ b/tools/testing/selftests/bpf/prog_tests/stacktrace_map.c
>> @@ -3,7 +3,7 @@
>>
>> void test_stacktrace_map(void)
>> {
>> - int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd;
>> + int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd, stack_key_map_fd;
>> const char *prog_name = "oncpu";
>> int err, prog_fd, stack_trace_len;
>> const char *file = "./test_stacktrace_map.bpf.o";
>> @@ -11,6 +11,9 @@ void test_stacktrace_map(void)
>> struct bpf_program *prog;
>> struct bpf_object *obj;
>> struct bpf_link *link;
>> + __u32 stackmap_key;
>> + char val_buf[PERF_MAX_STACK_DEPTH *
>> + sizeof(struct bpf_stack_build_id)];
>>
>> err = bpf_prog_test_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
>> if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno))
>> @@ -41,6 +44,10 @@ void test_stacktrace_map(void)
>> if (CHECK_FAIL(stack_amap_fd < 0))
>> goto disable_pmu;
>>
>> + stack_key_map_fd = bpf_find_map(__func__, obj, "stack_key_map");
>> + if (CHECK_FAIL(stack_key_map_fd < 0))
>> + goto disable_pmu;
>> +
>> /* give some time for bpf program run */
>> sleep(1);
>>
>> @@ -68,6 +75,15 @@ void test_stacktrace_map(void)
>> "err %d errno %d\n", err, errno))
>> goto disable_pmu;
>>
>> + err = bpf_map_lookup_elem(stack_key_map_fd, &key, &stackmap_key);
>> + if (CHECK(err, "stack_key_map lookup", "err %d errno %d\n", err, errno))
>> + goto disable_pmu;
>> +
>> + err = bpf_map_lookup_and_delete_elem(stackmap_fd, &stackmap_key, &val_buf);
>> + if (CHECK(err, "stackmap lookup and detele",
>
> nit typo 's/detele/delete/'
my fault, will fix it in v2.
>
>> + "err %d errno %d\n", err, errno))
>> + goto disable_pmu;
>
> should we also check the record got deleted? like make sure following
> lookup fails with NOENT:
>
yes we can, will add it in v2. Thanks.
> bpf_map_lookup_elem(stackmap_fd, &stackmap_key, &val_buf)
>
>> +
>> disable_pmu:
>> bpf_link__destroy(link);
>> close_prog:
>> diff --git a/tools/testing/selftests/bpf/progs/test_stacktrace_map.c b/tools/testing/selftests/bpf/progs/test_stacktrace_map.c
>> index 47568007b66..d036e8e9c83 100644
>> --- a/tools/testing/selftests/bpf/progs/test_stacktrace_map.c
>> +++ b/tools/testing/selftests/bpf/progs/test_stacktrace_map.c
>> @@ -38,6 +38,13 @@ struct {
>> __type(value, stack_trace_t);
>> } stack_amap SEC(".maps");
>>
>> +struct {
>> + __uint(type, BPF_MAP_TYPE_ARRAY);
>> + __uint(max_entries, 1);
>> + __type(key, __u32);
>> + __type(value, __u32);
>> +} stack_key_map SEC(".maps");
>> +
>> /* taken from /sys/kernel/tracing/events/sched/sched_switch/format */
>> struct sched_switch_args {
>> unsigned long long pad;
>> @@ -54,7 +61,7 @@ SEC("tracepoint/sched/sched_switch")
>> int oncpu(struct sched_switch_args *ctx)
>> {
>> __u32 max_len = PERF_MAX_STACK_DEPTH * sizeof(__u64);
>> - __u32 key = 0, val = 0, *value_p;
>> + __u32 key = 0, val = 0, *value_p, stackmap_key = 0;
>> void *stack_p;
>>
>> value_p = bpf_map_lookup_elem(&control_map, &key);
>> @@ -64,6 +71,9 @@ int oncpu(struct sched_switch_args *ctx)
>> /* The size of stackmap and stackid_hmap should be the same */
>> key = bpf_get_stackid(ctx, &stackmap, 0);
>> if ((int)key >= 0) {
>> + val = key;
>> + bpf_map_update_elem(&stack_key_map, &stackmap_key, &val, 0);
>
> why not use '&key' directly as the update value?
>
will clean it in v2.
> jirka
>
>
>> + val = 0;
>> bpf_map_update_elem(&stackid_hmap, &key, &val, 0);
>> stack_p = bpf_map_lookup_elem(&stack_amap, &key);
>> if (stack_p)
>> --
>> 2.48.1
>>
>>
--
Best Regards
Tao Chen
prev parent reply other threads:[~2025-09-09 13:08 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-08 11:36 [PATCH bpf-next 1/2] bpf: Add lookup_and_delete_elem for BPF_MAP_STACK_TRACE Tao Chen
2025-09-08 11:36 ` [PATCH bpf-next 2/2] selftests/bpf: Add stacktrace map lookup_and_delete_elem test case Tao Chen
2025-09-09 12:35 ` Jiri Olsa
2025-09-09 13:07 ` Tao Chen [this message]
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