Commit 89dc8d0c authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by Daniel Borkmann
Browse files

samples/bpf: Reduce syscall overhead in map_perf_test. 



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: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarKumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220902211058.60789-5-alexei.starovoitov@gmail.com
parent 37521bff

samples/bpf/map_perf_test_kern.c

+28 −16
Original line number Diff line number Diff line
@@ -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;



	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;



	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;



	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;



	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;

}

samples/bpf/map_perf_test_user.c

+1 −1
Original line number Diff line number Diff line
@@ -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)

{