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libbpf-tools/profile: Batch lookup support for hash map #4990

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libbpf-tools/profile: Batch lookup support for hash map #4990

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30 changes: 17 additions & 13 deletions libbpf-tools/profile.c
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@
#include "profile.h"
#include "profile.skel.h"
#include "trace_helpers.h"
#include "map_helpers.h"

#define OPT_PERF_MAX_STACK_DEPTH 1 /* --perf-max-stack-depth */
#define OPT_STACK_STORAGE_SIZE 2 /* --stack-storage-size */
Expand Down Expand Up @@ -270,26 +271,29 @@ static int cmp_counts(const void *a, const void *b)

static int read_counts_map(int fd, struct key_ext_t *items, __u32 *count)
{
struct key_t keys[*count];
__u64 vals[*count];
__u32 key_size = sizeof(keys[0]);
__u32 value_size = sizeof(__u64);
struct key_t empty = {};
struct key_t *lookup_key = ∅
int i = 0;
int err;
__u32 n = *count;

while (bpf_map_get_next_key(fd, lookup_key, &items[i].k) == 0) {
err = bpf_map_lookup_elem(fd, &items[i].k, &items[i].v);
if (err < 0) {
fprintf(stderr, "failed to lookup counts: %d\n", err);
return -err;
}

if (items[i].v == 0)
continue;
err = dump_hash(fd, keys, key_size, vals, value_size, &n, &empty);
if (err)
return err;

lookup_key = &items[i].k;
i++;
for (i = 0; i < n; i++) {
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In previous patches, maps were read directly into the "items" variable, so this copy would not work unless it was in a batch. Now we use a little more memory and CPU. However, this change is good for eliminating duplicate code.

items[i].k.pid = keys[i].pid;
items[i].k.user_stack_id = keys[i].user_stack_id;
items[i].k.kern_stack_id = keys[i].kern_stack_id;
strncpy(items[i].k.name, keys[i].name, TASK_COMM_LEN);
items[i].v = vals[i];
}

*count = i;
*count = n;

return 0;
}

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