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Message-ID: <1489627604-2288703-7-git-send-email-ast@fb.com>
Date: Wed, 15 Mar 2017 18:26:44 -0700
From: Alexei Starovoitov <ast@...com>
To: "David S . Miller" <davem@...emloft.net>
CC: Daniel Borkmann <daniel@...earbox.net>,
Fengguang Wu <fengguang.wu@...el.com>,
<netdev@...r.kernel.org>, <kernel-team@...com>
Subject: [PATCH net-next 6/6] samples/bpf: add map_lookup microbenchmark
$ map_perf_test 128
speed of HASH bpf_map_lookup_elem() in lookups per second
w/o JIT w/JIT
before 46M 58M
after 42M 74M
perf report
before:
54.23% map_perf_test [kernel.kallsyms] [k] __htab_map_lookup_elem
14.24% map_perf_test [kernel.kallsyms] [k] lookup_elem_raw
8.84% map_perf_test [kernel.kallsyms] [k] htab_map_lookup_elem
5.93% map_perf_test [kernel.kallsyms] [k] bpf_map_lookup_elem
2.30% map_perf_test [kernel.kallsyms] [k] bpf_prog_da4fc6a3f41761a2
1.49% map_perf_test [kernel.kallsyms] [k] kprobe_ftrace_handler
after:
60.03% map_perf_test [kernel.kallsyms] [k] __htab_map_lookup_elem
18.07% map_perf_test [kernel.kallsyms] [k] lookup_elem_raw
2.91% map_perf_test [kernel.kallsyms] [k] bpf_prog_da4fc6a3f41761a2
1.94% map_perf_test [kernel.kallsyms] [k] _einittext
1.90% map_perf_test [kernel.kallsyms] [k] __audit_syscall_exit
1.72% map_perf_test [kernel.kallsyms] [k] kprobe_ftrace_handler
Notice that bpf_map_lookup_elem() and htab_map_lookup_elem() are trivial
functions, yet they take sizeable amount of cpu time.
htab_map_gen_lookup() removes bpf_map_lookup_elem() and converts
htab_map_lookup_elem() into three BPF insns which causing cpu time
for bpf_prog_da4fc6a3f41761a2() slightly increase.
$ map_perf_test 256
speed of ARRAY bpf_map_lookup_elem() in lookups per second
w/o JIT w/JIT
before 97M 174M
after 64M 280M
before:
37.33% map_perf_test [kernel.kallsyms] [k] array_map_lookup_elem
13.95% map_perf_test [kernel.kallsyms] [k] bpf_map_lookup_elem
6.54% map_perf_test [kernel.kallsyms] [k] bpf_prog_da4fc6a3f41761a2
4.57% map_perf_test [kernel.kallsyms] [k] kprobe_ftrace_handler
after:
32.86% map_perf_test [kernel.kallsyms] [k] bpf_prog_da4fc6a3f41761a2
6.54% map_perf_test [kernel.kallsyms] [k] kprobe_ftrace_handler
array_map_gen_lookup() removes calls to array_map_lookup_elem()
and bpf_map_lookup_elem() and replaces them with 7 bpf insns.
The performance without JIT is slower, since executing extra insns
in the interpreter is slower than running native C code,
but with JIT the performance gains are obvious,
since native C->x86 code is replaced with fewer bpf->x86 instructions.
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
Acked-by: Daniel Borkmann <daniel@...earbox.net>
---
samples/bpf/map_perf_test_kern.c | 33 +++++++++++++++++++++++++++++++++
samples/bpf/map_perf_test_user.c | 32 ++++++++++++++++++++++++++++++++
2 files changed, 65 insertions(+)
diff --git a/samples/bpf/map_perf_test_kern.c b/samples/bpf/map_perf_test_kern.c
index a91872a97742..9da2a3441b0a 100644
--- a/samples/bpf/map_perf_test_kern.c
+++ b/samples/bpf/map_perf_test_kern.c
@@ -65,6 +65,13 @@ struct bpf_map_def SEC("maps") lpm_trie_map_alloc = {
.map_flags = BPF_F_NO_PREALLOC,
};
+struct bpf_map_def SEC("maps") array_map = {
+ .type = BPF_MAP_TYPE_ARRAY,
+ .key_size = sizeof(u32),
+ .value_size = sizeof(long),
+ .max_entries = MAX_ENTRIES,
+};
+
SEC("kprobe/sys_getuid")
int stress_hmap(struct pt_regs *ctx)
{
@@ -165,5 +172,31 @@ int stress_lpm_trie_map_alloc(struct pt_regs *ctx)
return 0;
}
+SEC("kprobe/sys_getpgid")
+int stress_hash_map_lookup(struct pt_regs *ctx)
+{
+ u32 key = 1, i;
+ long *value;
+
+#pragma clang loop unroll(full)
+ for (i = 0; i < 64; ++i)
+ value = bpf_map_lookup_elem(&hash_map, &key);
+
+ return 0;
+}
+
+SEC("kprobe/sys_getpgrp")
+int stress_array_map_lookup(struct pt_regs *ctx)
+{
+ u32 key = 1, i;
+ long *value;
+
+#pragma clang loop unroll(full)
+ for (i = 0; i < 64; ++i)
+ value = bpf_map_lookup_elem(&array_map, &key);
+
+ return 0;
+}
+
char _license[] SEC("license") = "GPL";
u32 _version SEC("version") = LINUX_VERSION_CODE;
diff --git a/samples/bpf/map_perf_test_user.c b/samples/bpf/map_perf_test_user.c
index 680260a91f50..e29ff318a793 100644
--- a/samples/bpf/map_perf_test_user.c
+++ b/samples/bpf/map_perf_test_user.c
@@ -38,6 +38,8 @@ static __u64 time_get_ns(void)
#define LRU_HASH_PREALLOC (1 << 4)
#define PERCPU_LRU_HASH_PREALLOC (1 << 5)
#define LPM_KMALLOC (1 << 6)
+#define HASH_LOOKUP (1 << 7)
+#define ARRAY_LOOKUP (1 << 8)
static int test_flags = ~0;
@@ -125,6 +127,30 @@ static void test_lpm_kmalloc(int cpu)
cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
}
+static void test_hash_lookup(int cpu)
+{
+ __u64 start_time;
+ int i;
+
+ start_time = time_get_ns();
+ for (i = 0; i < MAX_CNT; i++)
+ syscall(__NR_getpgid, 0);
+ printf("%d:hash_lookup %lld lookups per sec\n",
+ cpu, MAX_CNT * 1000000000ll * 64 / (time_get_ns() - start_time));
+}
+
+static void test_array_lookup(int cpu)
+{
+ __u64 start_time;
+ int i;
+
+ start_time = time_get_ns();
+ for (i = 0; i < MAX_CNT; i++)
+ syscall(__NR_getpgrp, 0);
+ printf("%d:array_lookup %lld lookups per sec\n",
+ cpu, MAX_CNT * 1000000000ll * 64 / (time_get_ns() - start_time));
+}
+
static void loop(int cpu)
{
cpu_set_t cpuset;
@@ -153,6 +179,12 @@ static void loop(int cpu)
if (test_flags & LPM_KMALLOC)
test_lpm_kmalloc(cpu);
+
+ if (test_flags & HASH_LOOKUP)
+ test_hash_lookup(cpu);
+
+ if (test_flags & ARRAY_LOOKUP)
+ test_array_lookup(cpu);
}
static void run_perf_test(int tasks)
--
2.8.0
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