diff options
| author | Martin KaFai Lau <kafai@fb.com> | 2017-08-31 23:27:13 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-09-01 09:57:39 -0700 |
| commit | bb9b9f8802212d98e70c63045b1734162945eaa5 (patch) | |
| tree | 271be828c272d07ad318ee244e27dd77c38bb34e /kernel | |
| parent | cc555421bc118edd070f41258d6f55f1ccfc2558 (diff) | |
bpf: Only set node->ref = 1 if it has not been set
This patch writes 'node->ref = 1' only if node->ref is 0.
The number of lookups/s for a ~1M entries LRU map increased by
~30% (260097 to 343313).
Other writes on 'node->ref = 0' is not changed. In those cases, the
same cache line has to be changed anyway.
First column: Size of the LRU hash
Second column: Number of lookups/s
Before:
> echo "$((2**20+1)): $(./map_perf_test 1024 1 $((2**20+1)) 10000000 | awk '{print $3}')"
1048577: 260097
After:
> echo "$((2**20+1)): $(./map_perf_test 1024 1 $((2**20+1)) 10000000 | awk '{print $3}')"
1048577: 343313
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/bpf_lru_list.h | 3 | ||||
| -rw-r--r-- | kernel/bpf/hashtab.c | 7 |
2 files changed, 8 insertions, 2 deletions
diff --git a/kernel/bpf/bpf_lru_list.h b/kernel/bpf/bpf_lru_list.h index 5c35a98d02bf..7d4f89b7cb84 100644 --- a/kernel/bpf/bpf_lru_list.h +++ b/kernel/bpf/bpf_lru_list.h @@ -69,7 +69,8 @@ static inline void bpf_lru_node_set_ref(struct bpf_lru_node *node) /* ref is an approximation on access frequency. It does not * have to be very accurate. Hence, no protection is used. */ - node->ref = 1; + if (!node->ref) + node->ref = 1; } int bpf_lru_init(struct bpf_lru *lru, bool percpu, u32 hash_offset, diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 682f4543fefa..431126f31ea3 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -519,9 +519,14 @@ static u32 htab_lru_map_gen_lookup(struct bpf_map *map, { struct bpf_insn *insn = insn_buf; const int ret = BPF_REG_0; + const int ref_reg = BPF_REG_1; *insn++ = BPF_EMIT_CALL((u64 (*)(u64, u64, u64, u64, u64))__htab_map_lookup_elem); - *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 2); + *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 4); + *insn++ = BPF_LDX_MEM(BPF_B, ref_reg, ret, + offsetof(struct htab_elem, lru_node) + + offsetof(struct bpf_lru_node, ref)); + *insn++ = BPF_JMP_IMM(BPF_JNE, ref_reg, 0, 1); *insn++ = BPF_ST_MEM(BPF_B, ret, offsetof(struct htab_elem, lru_node) + offsetof(struct bpf_lru_node, ref), |