From: Joanne Koong <joannekoong@fb.com>
To: <bpf@vger.kernel.org>
Cc: <Kernel-team@fb.com>
Subject: Re: [PATCH v3 bpf-next 2/5] libbpf: Allow the number of hashes in bloom filter maps to be configurable
Date: Tue, 21 Sep 2021 15:24:35 -0700 [thread overview]
Message-ID: <9d26bf60-6a74-f994-d199-1babcd4b1943@fb.com> (raw)
In-Reply-To: <20210921210225.4095056-3-joannekoong@fb.com>
On 9/21/21 2:02 PM, Joanne Koong wrote:
> This patch adds the libbpf infrastructure that will allow the user to
> specify a configurable number of hash functions to use for the bloom
> filter map.
>
> Please note that this patch does not enforce that a pinned bloom filter
> map may only be reused if the number of hash functions is the same. If
> they are not the same, the number of hash functions used will be the one
> that was set for the pinned map.
>
> Signed-off-by: Joanne Koong <joannekoong@fb.com>
> ---
> include/uapi/linux/bpf.h | 5 ++++-
> tools/include/uapi/linux/bpf.h | 5 ++++-
> tools/lib/bpf/bpf.c | 2 ++
> tools/lib/bpf/bpf.h | 1 +
> tools/lib/bpf/libbpf.c | 32 +++++++++++++++++++++++++++-----
> tools/lib/bpf/libbpf.h | 2 ++
> tools/lib/bpf/libbpf.map | 1 +
> tools/lib/bpf/libbpf_internal.h | 4 +++-
> 8 files changed, 44 insertions(+), 8 deletions(-)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index fec9fcfe0629..2e3048488feb 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -1262,7 +1262,10 @@ union bpf_attr {
> __u32 map_flags; /* BPF_MAP_CREATE related
> * flags defined above.
> */
> - __u32 inner_map_fd; /* fd pointing to the inner map */
> + union {
> + __u32 inner_map_fd; /* fd pointing to the inner map */
> + __u32 nr_hash_funcs; /* or number of hash functions */
> + };
> __u32 numa_node; /* numa node (effective only if
> * BPF_F_NUMA_NODE is set).
> */
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index fec9fcfe0629..2e3048488feb 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -1262,7 +1262,10 @@ union bpf_attr {
> __u32 map_flags; /* BPF_MAP_CREATE related
> * flags defined above.
> */
> - __u32 inner_map_fd; /* fd pointing to the inner map */
> + union {
> + __u32 inner_map_fd; /* fd pointing to the inner map */
> + __u32 nr_hash_funcs; /* or number of hash functions */
> + };
> __u32 numa_node; /* numa node (effective only if
> * BPF_F_NUMA_NODE is set).
> */
> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> index 2401fad090c5..8a9dd4f6d6c8 100644
> --- a/tools/lib/bpf/bpf.c
> +++ b/tools/lib/bpf/bpf.c
> @@ -100,6 +100,8 @@ int bpf_create_map_xattr(const struct bpf_create_map_attr *create_attr)
> if (attr.map_type == BPF_MAP_TYPE_STRUCT_OPS)
> attr.btf_vmlinux_value_type_id =
> create_attr->btf_vmlinux_value_type_id;
> + else if (attr.map_type == BPF_MAP_TYPE_BLOOM_FILTER)
> + attr.nr_hash_funcs = create_attr->nr_hash_funcs;
> else
> attr.inner_map_fd = create_attr->inner_map_fd;
>
> diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
> index 6fffb3cdf39b..1194b6f01572 100644
> --- a/tools/lib/bpf/bpf.h
> +++ b/tools/lib/bpf/bpf.h
> @@ -49,6 +49,7 @@ struct bpf_create_map_attr {
> union {
> __u32 inner_map_fd;
> __u32 btf_vmlinux_value_type_id;
> + __u32 nr_hash_funcs;
> };
> };
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index da65a1666a5e..e51e68a07aaf 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -378,6 +378,7 @@ struct bpf_map {
> char *pin_path;
> bool pinned;
> bool reused;
> + __u32 nr_hash_funcs;
> };
>
> enum extern_type {
> @@ -1291,6 +1292,11 @@ static bool bpf_map_type__is_map_in_map(enum bpf_map_type type)
> return false;
> }
>
> +static inline bool bpf_map__is_bloom_filter(const struct bpf_map *map)
> +{
> + return map->def.type == BPF_MAP_TYPE_BLOOM_FILTER;
> +}
> +
> int bpf_object__section_size(const struct bpf_object *obj, const char *name,
> __u32 *size)
> {
> @@ -2238,6 +2244,10 @@ int parse_btf_map_def(const char *map_name, struct btf *btf,
> }
> map_def->pinning = val;
> map_def->parts |= MAP_DEF_PINNING;
> + } else if (strcmp(name, "nr_hash_funcs") == 0) {
> + if (!get_map_field_int(map_name, btf, m, &map_def->nr_hash_funcs))
> + return -EINVAL;
> + map_def->parts |= MAP_DEF_NR_HASH_FUNCS;
> } else {
> if (strict) {
> pr_warn("map '%s': unknown field '%s'.\n", map_name, name);
> @@ -2266,6 +2276,7 @@ static void fill_map_from_def(struct bpf_map *map, const struct btf_map_def *def
> map->numa_node = def->numa_node;
> map->btf_key_type_id = def->key_type_id;
> map->btf_value_type_id = def->value_type_id;
> + map->nr_hash_funcs = def->nr_hash_funcs;
>
> if (def->parts & MAP_DEF_MAP_TYPE)
> pr_debug("map '%s': found type = %u.\n", map->name, def->map_type);
> @@ -2290,6 +2301,8 @@ static void fill_map_from_def(struct bpf_map *map, const struct btf_map_def *def
> pr_debug("map '%s': found pinning = %u.\n", map->name, def->pinning);
> if (def->parts & MAP_DEF_NUMA_NODE)
> pr_debug("map '%s': found numa_node = %u.\n", map->name, def->numa_node);
> + if (def->parts & MAP_DEF_NR_HASH_FUNCS)
> + pr_debug("map '%s': found nr_hash_funcs = %u.\n", map->name, def->nr_hash_funcs);
>
> if (def->parts & MAP_DEF_INNER_MAP)
> pr_debug("map '%s': found inner map definition.\n", map->name);
> @@ -4616,10 +4629,6 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, b
> create_attr.max_entries = def->max_entries;
> }
>
> - if (bpf_map__is_struct_ops(map))
> - create_attr.btf_vmlinux_value_type_id =
> - map->btf_vmlinux_value_type_id;
> -
> create_attr.btf_fd = 0;
> create_attr.btf_key_type_id = 0;
> create_attr.btf_value_type_id = 0;
> @@ -4629,7 +4638,12 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, b
> create_attr.btf_value_type_id = map->btf_value_type_id;
> }
>
> - if (bpf_map_type__is_map_in_map(def->type)) {
> + if (bpf_map__is_struct_ops(map)) {
> + create_attr.btf_vmlinux_value_type_id =
> + map->btf_vmlinux_value_type_id;
> + } else if (bpf_map__is_bloom_filter(map)) {
> + create_attr.nr_hash_funcs = map->nr_hash_funcs;
> + } else if (bpf_map_type__is_map_in_map(def->type)) {
> if (map->inner_map) {
> err = bpf_object__create_map(obj, map->inner_map, true);
> if (err) {
> @@ -8610,6 +8624,14 @@ int bpf_map__set_value_size(struct bpf_map *map, __u32 size)
> return 0;
> }
>
> +int bpf_map__set_nr_hash_funcs(struct bpf_map *map, __u32 nr_hash_funcs)
> +{
> + if (map->fd >= 0)
> + return libbpf_err(-EBUSY);
> + map->nr_hash_funcs = nr_hash_funcs;
> + return 0;
> +}
> +
> __u32 bpf_map__btf_key_type_id(const struct bpf_map *map)
> {
> return map ? map->btf_key_type_id : 0;
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index d0bedd673273..5c441744f766 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -550,6 +550,8 @@ LIBBPF_API __u32 bpf_map__btf_value_type_id(const struct bpf_map *map);
> /* get/set map if_index */
> LIBBPF_API __u32 bpf_map__ifindex(const struct bpf_map *map);
> LIBBPF_API int bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex);
> +/* set nr_hash_funcs */
> +LIBBPF_API int bpf_map__set_nr_hash_funcs(struct bpf_map *map, __u32 nr_hash_funcs);
>
> typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *);
> LIBBPF_API int bpf_map__set_priv(struct bpf_map *map, void *priv,
> diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> index 9e649cf9e771..ee0e1e7648f4 100644
> --- a/tools/lib/bpf/libbpf.map
> +++ b/tools/lib/bpf/libbpf.map
> @@ -385,6 +385,7 @@ LIBBPF_0.5.0 {
> btf__load_vmlinux_btf;
> btf_dump__dump_type_data;
> libbpf_set_strict_mode;
> + bpf_map__set_nr_hash_funcs;
> } LIBBPF_0.4.0;
>
> LIBBPF_0.6.0 {
> diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
> index ceb0c98979bc..95dbbeba231f 100644
> --- a/tools/lib/bpf/libbpf_internal.h
> +++ b/tools/lib/bpf/libbpf_internal.h
> @@ -186,8 +186,9 @@ enum map_def_parts {
> MAP_DEF_NUMA_NODE = 0x080,
> MAP_DEF_PINNING = 0x100,
> MAP_DEF_INNER_MAP = 0x200,
> + MAP_DEF_NR_HASH_FUNCS = 0x400,
>
> - MAP_DEF_ALL = 0x3ff, /* combination of all above */
> + MAP_DEF_ALL = 0x7ff, /* combination of all above */
> };
>
> struct btf_map_def {
> @@ -201,6 +202,7 @@ struct btf_map_def {
> __u32 map_flags;
> __u32 numa_node;
> __u32 pinning;
> + __u32 nr_hash_funcs;
> };
>
I just realized that Andrii's comment on v1 stated that btf_map_def is
fixed indefinitely.
This implies that for bloom filter maps where the number of hash
functions needs to be set,
we will not be able to use the BTF-defined format and will instead need
to use the older
map definition that uses bpf_map_def. Is my understanding of this
correct? If so, I will go
ahead and fix this for v4.
> int parse_btf_map_def(const char *map_name, struct btf *btf,
next prev parent reply other threads:[~2021-09-21 22:24 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-21 21:02 [PATCH v3 bpf-next 0/5] Implement bloom filter map Joanne Koong
2021-09-21 21:02 ` [PATCH v3 bpf-next 1/5] bpf: Add bloom filter map implementation Joanne Koong
2021-09-21 23:44 ` Andrii Nakryiko
2021-09-22 19:06 ` Joanne Koong
2021-09-22 19:38 ` Martin KaFai Lau
2021-09-22 20:52 ` Andrii Nakryiko
2021-09-22 22:08 ` Martin KaFai Lau
2021-09-22 23:07 ` Andrii Nakryiko
2021-09-23 1:28 ` Martin KaFai Lau
2021-09-23 18:42 ` Andrii Nakryiko
2021-09-23 19:42 ` Martin KaFai Lau
2021-09-23 20:30 ` Alexei Starovoitov
2021-09-23 21:12 ` Andrii Nakryiko
2021-09-23 22:28 ` Joanne Koong
2021-09-23 23:46 ` Martin KaFai Lau
2021-09-24 2:23 ` Andrii Nakryiko
2021-09-24 16:32 ` Joanne Koong
2021-09-24 23:12 ` Andrii Nakryiko
2021-09-27 16:41 ` Alexei Starovoitov
2021-09-27 21:14 ` Andrii Nakryiko
2021-09-27 23:51 ` Alexei Starovoitov
2021-09-28 0:36 ` Andrii Nakryiko
2021-09-28 16:21 ` Alexei Starovoitov
[not found] ` <aa967ed2-a958-f995-3a09-bbd6b6e775d4@fb.com>
2021-09-28 23:54 ` Andrii Nakryiko
2021-09-29 1:54 ` Joanne Koong
2021-09-29 0:14 ` Andrii Nakryiko
2021-09-29 3:17 ` Alexei Starovoitov
2021-09-29 3:38 ` Joanne Koong
2021-09-28 1:09 ` Martin KaFai Lau
2021-09-22 20:44 ` Andrii Nakryiko
2021-09-21 21:02 ` [PATCH v3 bpf-next 2/5] libbpf: Allow the number of hashes in bloom filter maps to be configurable Joanne Koong
2021-09-21 22:24 ` Joanne Koong [this message]
2021-09-22 23:14 ` Andrii Nakryiko
2021-09-21 23:57 ` Andrii Nakryiko
2021-09-21 21:02 ` [PATCH v3 bpf-next 3/5] selftests/bpf: Add bloom filter map test cases Joanne Koong
2021-09-21 21:02 ` [PATCH v3 bpf-next 4/5] bpf/benchs: Add benchmark test for bloom filter maps Joanne Koong
2021-09-21 21:02 ` [PATCH v3 bpf-next 5/5] bpf/benchs: Add benchmarks for comparing hashmap lookups with vs. without bloom filter Joanne Koong
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