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samples: bpf: Add xdp_exception tracepoint statistics support
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This implements the retrieval and printing, as well the help output.

Signed-off-by: Kumar Kartikeya Dwivedi <[email protected]>
Signed-off-by: Alexei Starovoitov <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]
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@kkdwivedi
kkdwivedi authored and Alexei Starovoitov committed Aug 24, 2021
1 parent 4515887 commit 82c4508
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Showing 2 changed files with 116 additions and 0 deletions.
113 changes: 113 additions & 0 deletions samples/bpf/xdp_sample_user.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -74,6 +74,7 @@
enum map_type {
MAP_RX,
MAP_REDIRECT_ERR,
MAP_EXCEPTION,
NUM_MAP,
};

Expand All @@ -98,6 +99,7 @@ struct map_entry {
struct stats_record {
struct record rx_cnt;
struct record redir_err[XDP_REDIRECT_ERR_MAX];
struct record exception[XDP_ACTION_MAX];
};

struct sample_output {
Expand All @@ -115,6 +117,9 @@ struct sample_output {
__u64 suc;
__u64 err;
} redir_cnt;
struct {
__u64 hits;
} except_cnt;
};

struct xdp_desc {
Expand Down Expand Up @@ -156,6 +161,15 @@ static const char *xdp_redirect_err_help[XDP_REDIRECT_ERR_MAX - 1] = {
"No space in ptr_ring of cpumap kthread",
};

static const char *xdp_action_names[XDP_ACTION_MAX] = {
[XDP_ABORTED] = "XDP_ABORTED",
[XDP_DROP] = "XDP_DROP",
[XDP_PASS] = "XDP_PASS",
[XDP_TX] = "XDP_TX",
[XDP_REDIRECT] = "XDP_REDIRECT",
[XDP_UNKNOWN] = "XDP_UNKNOWN",
};

static __u64 gettime(void)
{
struct timespec t;
Expand All @@ -169,6 +183,13 @@ static __u64 gettime(void)
return (__u64)t.tv_sec * NANOSEC_PER_SEC + t.tv_nsec;
}

static const char *action2str(int action)
{
if (action < XDP_ACTION_MAX)
return xdp_action_names[action];
return NULL;
}

static void sample_print_help(int mask)
{
printf("Output format description\n\n"
Expand Down Expand Up @@ -206,6 +227,15 @@ static void sample_print_help(int mask)

printf(" \n\t\t\t\terror/s - Packets that failed redirection per second\n\n");
}

if (mask & SAMPLE_EXCEPTION_CNT) {
printf(" xdp_exception\t\tDisplays xdp_exception tracepoint events\n"
" \t\t\tThis can occur due to internal driver errors, unrecognized\n"
" \t\t\tXDP actions and due to explicit user trigger by use of XDP_ABORTED\n"
" \t\t\tEach action is expanded below this field with its count\n"
" \t\t\t\thit/s - Number of times the tracepoint was hit per second\n\n");
}

}

void sample_usage(char *argv[], const struct option *long_options,
Expand Down Expand Up @@ -327,9 +357,26 @@ static struct stats_record *alloc_stats_record(void)
}
}
}
if (sample_mask & SAMPLE_EXCEPTION_CNT) {
for (i = 0; i < XDP_ACTION_MAX; i++) {
rec->exception[i].cpu = alloc_record_per_cpu();
if (!rec->exception[i].cpu) {
fprintf(stderr,
"Failed to allocate exception per-CPU array for "
"\"%s\" case\n",
action2str(i));
while (i--)
free(rec->exception[i].cpu);
goto end_redir;
}
}
}

return rec;

end_redir:
for (i = 0; i < XDP_REDIRECT_ERR_MAX; i++)
free(rec->redir_err[i].cpu);
end_rx_cnt:
free(rec->rx_cnt.cpu);
end_rec:
Expand All @@ -343,6 +390,8 @@ static void free_stats_record(struct stats_record *r)
struct map_entry *e;
int i;

for (i = 0; i < XDP_ACTION_MAX; i++)
free(r->exception[i].cpu);
for (i = 0; i < XDP_REDIRECT_ERR_MAX; i++)
free(r->redir_err[i].cpu);
free(r->rx_cnt.cpu);
Expand Down Expand Up @@ -551,6 +600,50 @@ static void stats_get_redirect_err_cnt(struct stats_record *stats_rec,
}
}

static void stats_get_exception_cnt(struct stats_record *stats_rec,
struct stats_record *stats_prev,
unsigned int nr_cpus,
struct sample_output *out)
{
double t, drop, sum = 0;
struct record *rec, *prev;
int rec_i, i;

for (rec_i = 0; rec_i < XDP_ACTION_MAX; rec_i++) {
rec = &stats_rec->exception[rec_i];
prev = &stats_prev->exception[rec_i];
t = calc_period(rec, prev);

drop = calc_drop_pps(&rec->total, &prev->total, t);
/* Fold out errors after heading */
sum += drop;

if (drop > 0 && !out) {
print_always(" %-18s " FMT_COLUMNf "\n",
action2str(rec_i), ERR(drop));

for (i = 0; i < nr_cpus; i++) {
struct datarec *r = &rec->cpu[i];
struct datarec *p = &prev->cpu[i];
char str[64];
double drop;

drop = calc_drop_pps(r, p, t);
if (!drop)
continue;

snprintf(str, sizeof(str), "cpu:%d", i);
print_default(" %-16s" FMT_COLUMNf "\n",
str, ERR(drop));
}
}
}

if (out) {
out->except_cnt.hits = sum;
out->totals.err += sum;
}
}

static void stats_print(const char *prefix, int mask, struct stats_record *r,
struct stats_record *p, struct sample_output *out)
Expand Down Expand Up @@ -595,6 +688,16 @@ static void stats_print(const char *prefix, int mask, struct stats_record *r,
stats_get_redirect_err_cnt(r, p, nr_cpus, NULL);
}

if (mask & SAMPLE_EXCEPTION_CNT) {
str = out->except_cnt.hits ? "xdp_exception total" :
"xdp_exception";

print_err(out->except_cnt.hits, " %-20s " FMT_COLUMNl "\n", str,
HITS(out->except_cnt.hits));

stats_get_exception_cnt(r, p, nr_cpus, NULL);
}

if (sample_log_level & LL_DEFAULT ||
((sample_log_level & LL_SIMPLE) && sample_err_exp)) {
sample_err_exp = false;
Expand All @@ -617,6 +720,9 @@ int sample_setup_maps(struct bpf_map **maps)
sample_map_count[i] =
XDP_REDIRECT_ERR_MAX * sample_n_cpus;
break;
case MAP_EXCEPTION:
sample_map_count[i] = XDP_ACTION_MAX * sample_n_cpus;
break;
default:
return -EINVAL;
}
Expand Down Expand Up @@ -788,6 +894,11 @@ static int sample_stats_collect(struct stats_record *rec)
&rec->redir_err[i]);
}

if (sample_mask & SAMPLE_EXCEPTION_CNT)
for (i = 0; i < XDP_ACTION_MAX; i++)
map_collect_percpu(&sample_mmap[MAP_EXCEPTION][i * sample_n_cpus],
&rec->exception[i]);

return 0;
}

Expand All @@ -811,6 +922,8 @@ static void sample_stats_print(int mask, struct stats_record *cur,
stats_get_redirect_cnt(cur, prev, 0, &out);
if (mask & SAMPLE_REDIRECT_ERR_CNT)
stats_get_redirect_err_cnt(cur, prev, 0, &out);
if (mask & SAMPLE_EXCEPTION_CNT)
stats_get_exception_cnt(cur, prev, 0, &out);
sample_summary_update(&out, interval);

stats_print(prog_name, mask, cur, prev, &out);
Expand Down
3 changes: 3 additions & 0 deletions samples/bpf/xdp_sample_user.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ enum stats_mask {
_SAMPLE_REDIRECT_MAP = 1U << 0,
SAMPLE_RX_CNT = 1U << 1,
SAMPLE_REDIRECT_ERR_CNT = 1U << 2,
SAMPLE_EXCEPTION_CNT = 1U << 5,
SAMPLE_REDIRECT_CNT = 1U << 7,
SAMPLE_REDIRECT_MAP_CNT = SAMPLE_REDIRECT_CNT | _SAMPLE_REDIRECT_MAP,
SAMPLE_REDIRECT_ERR_MAP_CNT = SAMPLE_REDIRECT_ERR_CNT | _SAMPLE_REDIRECT_MAP,
Expand Down Expand Up @@ -75,6 +76,8 @@ static inline char *safe_strncpy(char *dst, const char *src, size_t size)
__attach_tp(tp_xdp_redirect_map_err); \
if (mask & SAMPLE_REDIRECT_ERR_CNT) \
__attach_tp(tp_xdp_redirect_err); \
if (mask & SAMPLE_EXCEPTION_CNT) \
__attach_tp(tp_xdp_exception); \
return 0; \
}

Expand Down

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