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samples/bpf: Reduce syscall overhead in map_perf_test.

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Make map_perf_test for preallocated and non-preallocated hash map
spend more time inside bpf program to focus performance analysis
on the speed of update/lookup/delete operations performed by bpf program.

It makes 'perf report' of bpf_mem_alloc look like:
 11.76%  map_perf_test    [k] _raw_spin_lock_irqsave
 11.26%  map_perf_test    [k] htab_map_update_elem
  9.70%  map_perf_test    [k] _raw_spin_lock
  9.47%  map_perf_test    [k] htab_map_delete_elem
  8.57%  map_perf_test    [k] memcpy_erms
  5.58%  map_perf_test    [k] alloc_htab_elem
  4.09%  map_perf_test    [k] __htab_map_lookup_elem
  3.44%  map_perf_test    [k] syscall_exit_to_user_mode
  3.13%  map_perf_test    [k] lookup_nulls_elem_raw
  3.05%  map_perf_test    [k] migrate_enable
  3.04%  map_perf_test    [k] memcmp
  2.67%  map_perf_test    [k] unit_free
  2.39%  map_perf_test    [k] lookup_elem_raw

Reduce default iteration count as well to make 'map_perf_test' quick enough
even on debug kernels.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220902211058.60789-5-alexei.starovoitov@gmail.com
This commit is contained in:
Alexei Starovoitov 2022-09-02 14:10:46 -07:00 committed by Daniel Borkmann
parent 37521bffdd
commit 89dc8d0c38
2 changed files with 29 additions and 17 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

44
samples/bpf/map_perf_test_kern.c
View file

@ -108,11 +108,14 @@ int stress_hmap(struct pt_regs *ctx)
u32 key = bpf_get_current_pid_tgid();
long init_val = 1;
long *value;
int i;
bpf_map_update_elem(&hash_map, &key, &init_val, BPF_ANY);
value = bpf_map_lookup_elem(&hash_map, &key);
if (value)
bpf_map_delete_elem(&hash_map, &key);
for (i = 0; i < 10; i++) {
bpf_map_update_elem(&hash_map, &key, &init_val, BPF_ANY);
value = bpf_map_lookup_elem(&hash_map, &key);
if (value)
bpf_map_delete_elem(&hash_map, &key);
}
return 0;
}
@ -123,11 +126,14 @@ int stress_percpu_hmap(struct pt_regs *ctx)
u32 key = bpf_get_current_pid_tgid();
long init_val = 1;
long *value;
int i;
bpf_map_update_elem(&percpu_hash_map, &key, &init_val, BPF_ANY);
value = bpf_map_lookup_elem(&percpu_hash_map, &key);
if (value)
bpf_map_delete_elem(&percpu_hash_map, &key);
for (i = 0; i < 10; i++) {
bpf_map_update_elem(&percpu_hash_map, &key, &init_val, BPF_ANY);
value = bpf_map_lookup_elem(&percpu_hash_map, &key);
if (value)
bpf_map_delete_elem(&percpu_hash_map, &key);
}
return 0;
}
@ -137,11 +143,14 @@ int stress_hmap_alloc(struct pt_regs *ctx)
u32 key = bpf_get_current_pid_tgid();
long init_val = 1;
long *value;
int i;
bpf_map_update_elem(&hash_map_alloc, &key, &init_val, BPF_ANY);
value = bpf_map_lookup_elem(&hash_map_alloc, &key);
if (value)
bpf_map_delete_elem(&hash_map_alloc, &key);
for (i = 0; i < 10; i++) {
bpf_map_update_elem(&hash_map_alloc, &key, &init_val, BPF_ANY);
value = bpf_map_lookup_elem(&hash_map_alloc, &key);
if (value)
bpf_map_delete_elem(&hash_map_alloc, &key);
}
return 0;
}
@ -151,11 +160,14 @@ int stress_percpu_hmap_alloc(struct pt_regs *ctx)
u32 key = bpf_get_current_pid_tgid();
long init_val = 1;
long *value;
int i;
bpf_map_update_elem(&percpu_hash_map_alloc, &key, &init_val, BPF_ANY);
value = bpf_map_lookup_elem(&percpu_hash_map_alloc, &key);
if (value)
bpf_map_delete_elem(&percpu_hash_map_alloc, &key);
for (i = 0; i < 10; i++) {
bpf_map_update_elem(&percpu_hash_map_alloc, &key, &init_val, BPF_ANY);
value = bpf_map_lookup_elem(&percpu_hash_map_alloc, &key);
if (value)
bpf_map_delete_elem(&percpu_hash_map_alloc, &key);
}
return 0;
}

2
samples/bpf/map_perf_test_user.c
View file

@ -72,7 +72,7 @@ static int test_flags = ~0;
static uint32_t num_map_entries;
static uint32_t inner_lru_hash_size;
static int lru_hash_lookup_test_entries = 32;
static uint32_t max_cnt = 1000000;
static uint32_t max_cnt = 10000;
static int check_test_flags(enum test_type t)
{