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Commit b8a943e2 authored by David Herrmann's avatar David Herrmann Committed by David S. Miller
Browse files

samples/bpf: add lpm-trie benchmark 



Extend the map_perf_test_{user,kern}.c infrastructure to stress test
lpm-trie lookups. We hook into the kprobe on sys_gettid() and measure
the latency depending on trie size and lookup count.

On my Intel Haswell i7-6400U, a single gettid() syscall with an empty
bpf program takes roughly 6.5us on my system. Lookups in empty tries
take ~1.8us on first try, ~0.9us on retries. Lookups in tries with 8192
entries take ~7.1us (on the first _and_ any subsequent try).

Signed-off-by: default avatarDavid Herrmann <dh.herrmann@gmail.com>
Reviewed-by: default avatarDaniel Mack <daniel@zonque.org>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4d3381f5

samples/bpf/map_perf_test_kern.c

+30 −0
Original line number Diff line number Diff line
@@ -57,6 +57,14 @@ struct bpf_map_def SEC("maps") percpu_hash_map_alloc = { 
	.map_flags = BPF_F_NO_PREALLOC,

};



struct bpf_map_def SEC("maps") lpm_trie_map_alloc = {

	.type = BPF_MAP_TYPE_LPM_TRIE,

	.key_size = 8,

	.value_size = sizeof(long),

	.max_entries = 10000,

	.map_flags = BPF_F_NO_PREALLOC,

};



SEC("kprobe/sys_getuid")

int stress_hmap(struct pt_regs *ctx)

{
@@ -135,5 +143,27 @@ int stress_percpu_lru_hmap_alloc(struct pt_regs *ctx) 
	return 0;

}



SEC("kprobe/sys_gettid")

int stress_lpm_trie_map_alloc(struct pt_regs *ctx)

{

	union {

		u32 b32[2];

		u8 b8[8];

	} key;

	unsigned int i;



	key.b32[0] = 32;

	key.b8[4] = 192;

	key.b8[5] = 168;

	key.b8[6] = 0;

	key.b8[7] = 1;



#pragma clang loop unroll(full)

	for (i = 0; i < 32; ++i)

		bpf_map_lookup_elem(&lpm_trie_map_alloc, &key);



	return 0;

}



char _license[] SEC("license") = "GPL";

u32 _version SEC("version") = LINUX_VERSION_CODE;

samples/bpf/map_perf_test_user.c

+49 −0
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ static __u64 time_get_ns(void) 
#define PERCPU_HASH_KMALLOC	(1 << 3)

#define LRU_HASH_PREALLOC	(1 << 4)

#define PERCPU_LRU_HASH_PREALLOC	(1 << 5)

#define LPM_KMALLOC		(1 << 6)



static int test_flags = ~0;
@@ -112,6 +113,18 @@ static void test_percpu_hash_kmalloc(int cpu) 
	       cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));

}



static void test_lpm_kmalloc(int cpu)

{

	__u64 start_time;

	int i;



	start_time = time_get_ns();

	for (i = 0; i < MAX_CNT; i++)

		syscall(__NR_gettid);

	printf("%d:lpm_perf kmalloc %lld events per sec\n",

	       cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));

}



static void loop(int cpu)

{

	cpu_set_t cpuset;
@@ -137,6 +150,9 @@ static void loop(int cpu) 


	if (test_flags & PERCPU_LRU_HASH_PREALLOC)

		test_percpu_lru_hash_prealloc(cpu);



	if (test_flags & LPM_KMALLOC)

		test_lpm_kmalloc(cpu);

}



static void run_perf_test(int tasks)
@@ -162,6 +178,37 @@ static void run_perf_test(int tasks) 
	}

}



static void fill_lpm_trie(void)

{

	struct bpf_lpm_trie_key *key;

	unsigned long value = 0;

	unsigned int i;

	int r;



	key = alloca(sizeof(*key) + 4);

	key->prefixlen = 32;



	for (i = 0; i < 512; ++i) {

		key->prefixlen = rand() % 33;

		key->data[0] = rand() & 0xff;

		key->data[1] = rand() & 0xff;

		key->data[2] = rand() & 0xff;

		key->data[3] = rand() & 0xff;

		r = bpf_map_update_elem(map_fd[6], key, &value, 0);

		assert(!r);

	}



	key->prefixlen = 32;

	key->data[0] = 192;

	key->data[1] = 168;

	key->data[2] = 0;

	key->data[3] = 1;

	value = 128;



	r = bpf_map_update_elem(map_fd[6], key, &value, 0);

	assert(!r);

}



int main(int argc, char **argv)

{

	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
@@ -182,6 +229,8 @@ int main(int argc, char **argv) 
		return 1;

	}



	fill_lpm_trie();



	run_perf_test(num_cpu);



	return 0;