[PATCH bpf-next v1 2/4] bpftool: Add tools support to show BPF htab map's used size - Ho-Ren (Jack) Chuang

From: "Ho-Ren (Jack) Chuang" <horenchuang@bytedance.com>
To: Alexei Starovoitov <ast@kernel.org>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
	Jiri Olsa <olsajiri@gmail.com>,
	Andrii Nakryiko <andrii@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	John Fastabend <john.fastabend@gmail.com>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
	KP Singh <kpsingh@kernel.org>,
	Stanislav Fomichev <sdf@google.com>,
	Quentin Monnet <quentin@isovalent.com>,
	Mykola Lysenko <mykolal@fb.com>, Shuah Khan <shuah@kernel.org>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Tom Rix <trix@redhat.com>, Joanne Koong <joannelkoong@gmail.com>,
	Kui-Feng Lee <kuifeng@fb.com>,
	Lorenzo Bianconi <lorenzo@kernel.org>,
	Maxim Mikityanskiy <maximmi@nvidia.com>,
	Hao Xiang <hao.xiang@bytedance.com>,
	Punit Agrawal <punit.agrawal@bytedance.com>,
	Yifei Ma <yifeima@bytedance.com>,
	Xiaoning Ding <xiaoning.ding@bytedance.com>,
	bpf@vger.kernel.org
Cc: Ho-Ren Chuang <horenc@vt.edu>,
	Ho-Ren Chuang <horenchuang@bytedance.com>,
	linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	llvm@lists.linux.dev
Subject: [PATCH bpf-next v1 2/4] bpftool: Add tools support to show BPF htab map's used size
Date: Sat,  5 Nov 2022 02:51:44 +0000	[thread overview]
Message-ID: <20221105025146.238209-3-horenchuang@bytedance.com> (raw)
In-Reply-To: <20221105025146.238209-1-horenchuang@bytedance.com>

Add bpftool support for reporting the number of used entries of
htab maps by leveraging the newly added "used_entries" field in
struct bpf_map_info. It works with JSON as well.

To better understand actual used memory size of a htab map,
pre-allocated maps are now marked with "*" behind the "max_entries" size.

Signed-off-by: Ho-Ren (Jack) Chuang <horenchuang@bytedance.com>
---
 tools/bpf/bpftool/map.c        | 9 +++++++--
 tools/include/uapi/linux/bpf.h | 1 +
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index 9a6ca9f31133..0b07abae7309 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -475,6 +475,8 @@ static int show_map_close_json(int fd, struct bpf_map_info *info)
 	jsonw_uint_field(json_wtr, "bytes_key", info->key_size);
 	jsonw_uint_field(json_wtr, "bytes_value", info->value_size);
 	jsonw_uint_field(json_wtr, "max_entries", info->max_entries);
+	if (info->type == BPF_MAP_TYPE_HASH)
+		jsonw_uint_field(json_wtr, "used_entries", info->used_entries);
 
 	if (memlock)
 		jsonw_int_field(json_wtr, "bytes_memlock", atoll(memlock));
@@ -561,8 +563,11 @@ static int show_map_close_plain(int fd, struct bpf_map_info *info)
 	frozen_str = get_fdinfo(fd, "frozen");
 
 	show_map_header_plain(info);
-	printf("\tkey %uB  value %uB  max_entries %u",
-	       info->key_size, info->value_size, info->max_entries);
+	printf("\tkey %uB  value %uB  max_entries %u%1s",
+		   info->key_size, info->value_size, info->max_entries,
+		   !(info->map_flags & BPF_F_NO_PREALLOC) ? "*" : "");
+	if (info->type == BPF_MAP_TYPE_HASH)
+		printf("  used_entries %u", info->used_entries);
 
 	if (memlock)
 		printf("  memlock %sB", memlock);
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 17f61338f8f8..63659368cf0e 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -6215,6 +6215,7 @@ struct bpf_map_info {
 	__u32 id;
 	__u32 key_size;
 	__u32 value_size;
+	__u32 used_entries;
 	__u32 max_entries;
 	__u32 map_flags;
 	char  name[BPF_OBJ_NAME_LEN];
-- 
Ho-Ren (Jack) Chuang

