Re: [PATCH bpf-next] selftests/bpf: add more stats into veristat

[Mykyta Yatsenko <mykyta.yatsenko5@gmail.com>]

On 05/12/2024 23:50, Andrii Nakryiko wrote:
> On Thu, Dec 5, 2024 at 11:34 AM Mykyta Yatsenko
> <mykyta.yatsenko5@gmail.com> wrote:
>> From: Mykyta Yatsenko <yatsenko@meta.com>
>>
>> Extend veristat to collect and print more stats, namely:
>> - program size in instructions
>> - jited program size
>> - program type
>> - attach type
>> - stack depth
>>
>> Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
>> ---
>>   tools/testing/selftests/bpf/veristat.c | 51 +++++++++++++++++++++++---
>>   1 file changed, 46 insertions(+), 5 deletions(-)
>>
>> diff --git a/tools/testing/selftests/bpf/veristat.c b/tools/testing/selftests/bpf/veristat.c
>> index e12ef953fba8..0d7fb00175e8 100644
>> --- a/tools/testing/selftests/bpf/veristat.c
>> +++ b/tools/testing/selftests/bpf/veristat.c
>> @@ -38,8 +38,14 @@ enum stat_id {
>>          FILE_NAME,
>>          PROG_NAME,
>>
>> +       SIZE,
>> +       JITED_SIZE,
>> +       STACK,
>> +       PROG_TYPE,
>> +       ATTACH_TYPE,
>> +
>>          ALL_STATS_CNT,
>> -       NUM_STATS_CNT = FILE_NAME - VERDICT,
>> +       NUM_STATS_CNT = ATTACH_TYPE - VERDICT + 1,
> this doesn't sound right, because PROG_NAME isn't a number statistics
>
>>   };
>>
>>   /* In comparison mode each stat can specify up to four different values:
>> @@ -640,19 +646,22 @@ static int append_filter_file(const char *path)
>>   }
>>
>>   static const struct stat_specs default_output_spec = {
>> -       .spec_cnt = 7,
>> +       .spec_cnt = 12,
>>          .ids = {
>>                  FILE_NAME, PROG_NAME, VERDICT, DURATION,
>> -               TOTAL_INSNS, TOTAL_STATES, PEAK_STATES,
>> +               TOTAL_INSNS, TOTAL_STATES, PEAK_STATES, SIZE,
>> +               JITED_SIZE, PROG_TYPE, ATTACH_TYPE, STACK,
> I think SIZE or JITED_SIZE might be good candidates for default view,
> but not all of the above. I think we can also drop PEAK_STATES from
> default, btw.
>
>>          },
>>   };
>>
>>   static const struct stat_specs default_csv_output_spec = {
>> -       .spec_cnt = 9,
>> +       .spec_cnt = 14,
>>          .ids = {
>>                  FILE_NAME, PROG_NAME, VERDICT, DURATION,
>>                  TOTAL_INSNS, TOTAL_STATES, PEAK_STATES,
>>                  MAX_STATES_PER_INSN, MARK_READ_MAX_LEN,
>> +               SIZE, JITED_SIZE, PROG_TYPE, ATTACH_TYPE,
>> +               STACK,
> this is fine, we want everything in CSV, yep
>
>>          },
>>   };
>>
>> @@ -688,6 +697,11 @@ static struct stat_def {
>>          [PEAK_STATES] = { "Peak states", {"peak_states"}, },
>>          [MAX_STATES_PER_INSN] = { "Max states per insn", {"max_states_per_insn"}, },
>>          [MARK_READ_MAX_LEN] = { "Max mark read length", {"max_mark_read_len", "mark_read"}, },
>> +       [SIZE] = { "Prog size", {"prog_size", "size"}, },
> drop "size" alias, it's too ambiguous?
>
>> +       [JITED_SIZE] = { "Jited size", {"jited_size"}, },
> this probably should be prog_size_jited or something like that (I
> know, verbose, but unambiguous)
>
>> +       [STACK] = {"Stack depth", {"stack_depth", "stack"}, },
>> +       [PROG_TYPE] = { "Program type", {"program_type", "prog_type"}, },
> let's drop "program_type", verbose
>
>> +       [ATTACH_TYPE] = { "Attach type", {"attach_type", }, },
>>   };
>>
>>   static bool parse_stat_id_var(const char *name, size_t len, int *id,
>> @@ -853,13 +867,16 @@ static int parse_verif_log(char * const buf, size_t buf_sz, struct verif_stats *
>>
>>                  if (1 == sscanf(cur, "verification time %ld usec\n", &s->stats[DURATION]))
>>                          continue;
>> -               if (6 == sscanf(cur, "processed %ld insns (limit %*d) max_states_per_insn %ld total_states %ld peak_states %ld mark_read %ld",
>> +               if (5 == sscanf(cur, "processed %ld insns (limit %*d) max_states_per_insn %ld total_states %ld peak_states %ld mark_read %ld",
> is this a preexisting bug? why we didn't catch it before?
>
>>                                  &s->stats[TOTAL_INSNS],
>>                                  &s->stats[MAX_STATES_PER_INSN],
>>                                  &s->stats[TOTAL_STATES],
>>                                  &s->stats[PEAK_STATES],
>>                                  &s->stats[MARK_READ_MAX_LEN]))
>>                          continue;
>> +
>> +               if (1 == sscanf(cur, "stack depth %ld", &s->stats[STACK]))
> heh, not so simple, actually. stack depth is actually a list of stack
> sizes for main program and each subprogram. Try
>
> sudo ./veristat test_subprogs.bpf.o -v
>
> stack depth 8+8+0+0+8+0
>
> so we have to make some choices here, actually... we either parse that
> and add up, and/or we parse all that and associate it with individual
> subprograms.
>
> I think we can start with the former, but the latter is actually
> useful and quite tricky for humans to figure out because that order
> depends on libbpf-controlled order of subprograms (which veristat can
> get from btf_ext, I believe). Not sure if we need/want to record
> by-subprog breakdown into CSV, but it would be useful to have a more
> detailed breakdown by subprog in some verbose mode. Let's think about
> that.
>
>> +                       continue;
>>          }
>>
>>          return 0;
>> @@ -1146,8 +1163,11 @@ static int process_prog(const char *filename, struct bpf_object *obj, struct bpf
>>          char *buf;
>>          int buf_sz, log_level;
>>          struct verif_stats *stats;
>> +       struct bpf_prog_info info = {};
> this should be initialized with memset(0)
>
>> +       __u32 info_len = sizeof(info);
>>          int err = 0;
>>          void *tmp;
>> +       int fd;
>>
>>          if (!should_process_file_prog(base_filename, bpf_program__name(prog))) {
>>                  env.progs_skipped++;
>> @@ -1196,6 +1216,13 @@ static int process_prog(const char *filename, struct bpf_object *obj, struct bpf
>>          stats->file_name = strdup(base_filename);
>>          stats->prog_name = strdup(bpf_program__name(prog));
>>          stats->stats[VERDICT] = err == 0; /* 1 - success, 0 - failure */
>> +       stats->stats[SIZE] = bpf_program__insn_cnt(prog);
>> +       stats->stats[PROG_TYPE] = bpf_program__type(prog);
>> +       stats->stats[ATTACH_TYPE] = bpf_program__expected_attach_type(prog);
>> +       fd = bpf_program__fd(prog);
>> +       if (fd > 0 && bpf_prog_get_info_by_fd(fd, &info, &info_len) == 0)
>> +               stats->stats[JITED_SIZE] = info.jited_prog_len;
>> +
> please check that this is total length including all the subprogs
I think it does include subprogs. I checked this by loading program:
`bpftool prog load test_subprogs.bpf.o /sys/fs/bpf/test_subprogs`
then print its jited code:
`bpftool prog dump jited name prog1 test_subprogs.bpf.o`
summed sizes across all functions and compared with veristat output:
```
File                 Program  Verdict Duration (us)  Insns  States  Prog 
size  Jited size
-------------------  -------  -------  -------------  ----- ------  
---------  ----------
test_subprogs.bpf.o  prog1    success            181     56 6         
54         333
```
>>          parse_verif_log(buf, buf_sz, stats);
>>
>>          if (env.verbose) {
>> @@ -1309,6 +1336,11 @@ static int cmp_stat(const struct verif_stats *s1, const struct verif_stats *s2,
>>          case PROG_NAME:
>>                  cmp = strcmp(s1->prog_name, s2->prog_name);
>>                  break;
>> +       case ATTACH_TYPE:
>> +       case PROG_TYPE:
>> +       case SIZE:
>> +       case JITED_SIZE:
>> +       case STACK:
>>          case VERDICT:
>>          case DURATION:
>>          case TOTAL_INSNS:
>> @@ -1523,12 +1555,21 @@ static void prepare_value(const struct verif_stats *s, enum stat_id id,
>>                  else
>>                          *str = s->stats[VERDICT] ? "success" : "failure";
>>                  break;
>> +       case ATTACH_TYPE:
>> +               *str = s ? libbpf_bpf_attach_type_str(s->stats[ATTACH_TYPE]) ? : "N/A" : "N/A";
>> +               break;
>> +       case PROG_TYPE:
>> +               *str = s ? libbpf_bpf_prog_type_str(s->stats[PROG_TYPE]) ? : "N/A" : "N/A";
> let's not have x ? y ? z pattern, please do explicit outer if like we
> do for VERDICT
>
> pw-bot: cr
>
>> +               break;
>>          case DURATION:
>>          case TOTAL_INSNS:
>>          case TOTAL_STATES:
>>          case PEAK_STATES:
>>          case MAX_STATES_PER_INSN:
>>          case MARK_READ_MAX_LEN:
>> +       case STACK:
>> +       case SIZE:
>> +       case JITED_SIZE:
>>                  *val = s ? s->stats[id] : 0;
>>                  break;
>>          default:
>> --
>> 2.47.1
>>