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: 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

diff --git a/samples/bpf/map_perf_test_kern.c b/samples/bpf/map_perf_test_kern.c
index 8773f22b6a983cd51c1625270c3f930d6ac6d34b..7342c5b2f27873f7a620f3b4c841459f0c853c5a 100644 (file)
--- a/samples/bpf/map_perf_test_kern.c
+++ b/samples/bpf/map_perf_test_kern.c
@@ -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;
 }
 

diff --git a/samples/bpf/map_perf_test_user.c b/samples/bpf/map_perf_test_user.c
index b6fc174ab1f2148a2f99ca05be9625c70fc90af7..1bb53f4b29e11efc39458713c4871ac4c0ccecd4 100644 (file)
--- a/samples/bpf/map_perf_test_user.c
+++ b/samples/bpf/map_perf_test_user.c
@@ -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)
 {