Re: [PATCH bpf-next v3 3/3] bpf: selftests: update array map tests for per-cpu batched ops

[Martin KaFai Lau]

On Mon, Apr 12, 2021 at 04:40:01PM -0300, Pedro Tammela wrote:
> Follows the same logic as the hashtable tests.
> 
> Signed-off-by: Pedro Tammela <pctammela@xxxxxxxxxxxx>
> ---
>  .../bpf/map_tests/array_map_batch_ops.c       | 110 +++++++++++++-----
>  1 file changed, 80 insertions(+), 30 deletions(-)
> 
> diff --git a/tools/testing/selftests/bpf/map_tests/array_map_batch_ops.c b/tools/testing/selftests/bpf/map_tests/array_map_batch_ops.c
> index e42ea1195d18..707d17414dee 100644
> --- a/tools/testing/selftests/bpf/map_tests/array_map_batch_ops.c
> +++ b/tools/testing/selftests/bpf/map_tests/array_map_batch_ops.c
> @@ -10,32 +10,59 @@
>  #include <test_maps.h>
>  
>  static void map_batch_update(int map_fd, __u32 max_entries, int *keys,
> -			     int *values)
> +			     __s64 *values, bool is_pcpu)
>  {
> -	int i, err;
> +	int nr_cpus = libbpf_num_possible_cpus();
Instead of getting it multiple times, how about moving it out to
a static global and initialize it in test_array_map_batch_ops().


> +	int i, j, err;
> +	int offset = 0;
>  	DECLARE_LIBBPF_OPTS(bpf_map_batch_opts, opts,
>  		.elem_flags = 0,
>  		.flags = 0,
>  	);
>  
> +	CHECK(nr_cpus < 0, "nr_cpus checking",
> +	      "error: get possible cpus failed");
> +
>  	for (i = 0; i < max_entries; i++) {
>  		keys[i] = i;
> -		values[i] = i + 1;
> +		if (is_pcpu)
> +			for (j = 0; j < nr_cpus; j++)
> +				(values + offset)[j] = i + 1 + j;
> +		else
> +			values[i] = i + 1;
> +		offset += nr_cpus;
This "offset" update here is confusing to read because it is only
used in the is_pcpu case but it always gets updated regardless.
How about only defines and uses offset in the "if (is_pcpu)" case and
rename it to "cpu_offset": cpu_offset = i * nr_cpus.

The same goes for other occasions.

>  	}
>  
>  	err = bpf_map_update_batch(map_fd, keys, values, &max_entries, &opts);
>  	CHECK(err, "bpf_map_update_batch()", "error:%s\n", strerror(errno));
>  }
>  
> -static void map_batch_verify(int *visited, __u32 max_entries,
> -			     int *keys, int *values)
> +static void map_batch_verify(int *visited, __u32 max_entries, int *keys,
> +			     __s64 *values, bool is_pcpu)
>  {
> -	int i;
> +	int nr_cpus = libbpf_num_possible_cpus();
> +	int i, j;
> +	int offset = 0;
> +
> +	CHECK(nr_cpus < 0, "nr_cpus checking",
> +	      "error: get possible cpus failed");
>  
>  	memset(visited, 0, max_entries * sizeof(*visited));
>  	for (i = 0; i < max_entries; i++) {
> -		CHECK(keys[i] + 1 != values[i], "key/value checking",
> -		      "error: i %d key %d value %d\n", i, keys[i], values[i]);
> +		if (is_pcpu) {
> +			for (j = 0; j < nr_cpus; j++) {
> +				__s64 value = (values + offset)[j];
> +				CHECK(keys[i] + j + 1 != value,
> +				      "key/value checking",
> +				      "error: i %d j %d key %d value %d\n", i,
> +				      j, keys[i], value);
> +			}
> +		} else {
> +			CHECK(keys[i] + 1 != values[i], "key/value checking",
> +			      "error: i %d key %d value %d\n", i, keys[i],
> +			      values[i]);
> +		}
> +		offset += nr_cpus;
>  		visited[i] = 1;
>  	}
>  	for (i = 0; i < max_entries; i++) {
> @@ -44,45 +71,52 @@ static void map_batch_verify(int *visited, __u32 max_entries,
>  	}
>  }
>  
> -void test_array_map_batch_ops(void)
> +void __test_map_lookup_and_update_batch(bool is_pcpu)
static

>  {
> +	int nr_cpus = libbpf_num_possible_cpus();
>  	struct bpf_create_map_attr xattr = {
>  		.name = "array_map",
> -		.map_type = BPF_MAP_TYPE_ARRAY,
> +		.map_type = is_pcpu ? BPF_MAP_TYPE_PERCPU_ARRAY :
> +				      BPF_MAP_TYPE_ARRAY,
>  		.key_size = sizeof(int),
> -		.value_size = sizeof(int),
> +		.value_size = sizeof(__s64),
>  	};
> -	int map_fd, *keys, *values, *visited;
> +	int map_fd, *keys, *visited;
>  	__u32 count, total, total_success;
>  	const __u32 max_entries = 10;
>  	__u64 batch = 0;
> -	int err, step;
> +	int err, step, value_size;
> +	void *values;
>  	DECLARE_LIBBPF_OPTS(bpf_map_batch_opts, opts,
>  		.elem_flags = 0,
>  		.flags = 0,
>  	);
>  
> +	CHECK(nr_cpus < 0, "nr_cpus checking",
> +	      "error: get possible cpus failed");
> +
>  	xattr.max_entries = max_entries;
>  	map_fd = bpf_create_map_xattr(&xattr);
>  	CHECK(map_fd == -1,
>  	      "bpf_create_map_xattr()", "error:%s\n", strerror(errno));
>  
> -	keys = malloc(max_entries * sizeof(int));
> -	values = malloc(max_entries * sizeof(int));
> -	visited = malloc(max_entries * sizeof(int));
> +	value_size = sizeof(__s64);
> +	if (is_pcpu)
> +		value_size *= nr_cpus;
> +
> +	keys = malloc(max_entries * sizeof(*keys));
> +	values = calloc(max_entries, value_size);
Why only this one uses calloc?

> +	visited = malloc(max_entries * sizeof(*visited));
>  	CHECK(!keys || !values || !visited, "malloc()", "error:%s\n",
>  	      strerror(errno));
>  
> -	/* populate elements to the map */
> -	map_batch_update(map_fd, max_entries, keys, values);
> -
>  	/* test 1: lookup in a loop with various steps. */
>  	total_success = 0;
>  	for (step = 1; step < max_entries; step++) {
> -		map_batch_update(map_fd, max_entries, keys, values);
> -		map_batch_verify(visited, max_entries, keys, values);
> +		map_batch_update(map_fd, max_entries, keys, values, is_pcpu);
> +		map_batch_verify(visited, max_entries, keys, values, is_pcpu);
>  		memset(keys, 0, max_entries * sizeof(*keys));
> -		memset(values, 0, max_entries * sizeof(*values));
> +		memset(values, 0, max_entries * value_size);
>  		batch = 0;
>  		total = 0;
>  		/* iteratively lookup/delete elements with 'step'
> @@ -91,10 +125,10 @@ void test_array_map_batch_ops(void)
>  		count = step;
>  		while (true) {
>  			err = bpf_map_lookup_batch(map_fd,
> -						total ? &batch : NULL, &batch,
> -						keys + total,
> -						values + total,
> -						&count, &opts);
> +						   total ? &batch : NULL,
> +						   &batch, keys + total,
> +						   values + total * value_size,
> +						   &count, &opts);
>  
>  			CHECK((err && errno != ENOENT), "lookup with steps",
>  			      "error: %s\n", strerror(errno));
> @@ -108,7 +142,7 @@ void test_array_map_batch_ops(void)
>  		CHECK(total != max_entries, "lookup with steps",
>  		      "total = %u, max_entries = %u\n", total, max_entries);
>  
> -		map_batch_verify(visited, max_entries, keys, values);
> +		map_batch_verify(visited, max_entries, keys, values, is_pcpu);
>  
>  		total_success++;
>  	}
> @@ -116,9 +150,25 @@ void test_array_map_batch_ops(void)
>  	CHECK(total_success == 0, "check total_success",
>  	      "unexpected failure\n");
>  
> -	printf("%s:PASS\n", __func__);
> -
>  	free(keys);
> -	free(values);
>  	free(visited);
> +	free(values);
This re-ordering is unnecessary.

> +}
> +
> +void array_map_batch_ops(void)
static

> +{
> +	__test_map_lookup_and_update_batch(false);
> +	printf("test_%s:PASS\n", __func__);
> +}
> +
> +void array_percpu_map_batch_ops(void)
static

> +{
> +	__test_map_lookup_and_update_batch(true);
> +	printf("test_%s:PASS\n", __func__);
> +}
> +
> +void test_array_map_batch_ops(void)
> +{
> +	array_map_batch_ops();
> +	array_percpu_map_batch_ops();
>  }
> -- 
> 2.25.1
>