From: Stanislav Fomichev <sdf@google.com>
To: netdev@vger.kernel.org, bpf@vger.kernel.org
Cc: davem@davemloft.net, ast@kernel.org, daniel@iogearbox.net,
Stanislav Fomichev <sdf@google.com>
Subject: [PATCH bpf-next] libbpf: don't allocate 16M for log buffer by default
Date: Tue, 24 Mar 2020 16:31:20 -0700 [thread overview]
Message-ID: <20200324233120.66314-1-sdf@google.com> (raw)
For each prog/btf load we allocate and free 16 megs of verifier buffer.
On production systems it doesn't really make sense because the
programs/btf have gone through extensive testing and (mostly) guaranteed
to successfully load.
Let's switch to a much smaller buffer by default (128 bytes, sys_bpf
doesn't accept smaller log buffer) and resize it if the kernel returns
ENOSPC. On the first ENOSPC error we resize the buffer to BPF_LOG_BUF_SIZE
and then, on each subsequent ENOSPC, we keep doubling the buffer.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
tools/lib/bpf/btf.c | 10 +++++++++-
tools/lib/bpf/libbpf.c | 10 ++++++++--
tools/lib/bpf/libbpf_internal.h | 2 ++
3 files changed, 19 insertions(+), 3 deletions(-)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 3d1c25fc97ae..53c7efc3b347 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -657,13 +657,14 @@ int btf__finalize_data(struct bpf_object *obj, struct btf *btf)
int btf__load(struct btf *btf)
{
- __u32 log_buf_size = BPF_LOG_BUF_SIZE;
+ __u32 log_buf_size = BPF_MIN_LOG_BUF_SIZE;
char *log_buf = NULL;
int err = 0;
if (btf->fd >= 0)
return -EEXIST;
+retry_load:
log_buf = malloc(log_buf_size);
if (!log_buf)
return -ENOMEM;
@@ -673,6 +674,13 @@ int btf__load(struct btf *btf)
btf->fd = bpf_load_btf(btf->data, btf->data_size,
log_buf, log_buf_size, false);
if (btf->fd < 0) {
+ if (errno == ENOSPC) {
+ log_buf_size = max((__u32)BPF_LOG_BUF_SIZE,
+ log_buf_size << 1);
+ free(log_buf);
+ goto retry_load;
+ }
+
err = -errno;
pr_warn("Error loading BTF: %s(%d)\n", strerror(errno), errno);
if (*log_buf)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 085e41f9b68e..793c81b35ccc 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4855,7 +4855,7 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
{
struct bpf_load_program_attr load_attr;
char *cp, errmsg[STRERR_BUFSIZE];
- int log_buf_size = BPF_LOG_BUF_SIZE;
+ size_t log_buf_size = BPF_MIN_LOG_BUF_SIZE;
char *log_buf;
int btf_fd, ret;
@@ -4911,7 +4911,13 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
}
if (errno == ENOSPC) {
- log_buf_size <<= 1;
+ if (errno == ENOSPC) {
+ log_buf_size = max((size_t)BPF_LOG_BUF_SIZE,
+ log_buf_size << 1);
+ free(log_buf);
+ goto retry_load;
+ }
+
free(log_buf);
goto retry_load;
}
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 8c3afbd97747..2720f3366798 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -23,6 +23,8 @@
#define BTF_PARAM_ENC(name, type) (name), (type)
#define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size)
+#define BPF_MIN_LOG_BUF_SIZE 128
+
#ifndef min
# define min(x, y) ((x) < (y) ? (x) : (y))
#endif
--
2.25.1.696.g5e7596f4ac-goog
next reply other threads:[~2020-03-24 23:31 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-24 23:31 Stanislav Fomichev [this message]
2020-03-24 23:45 ` [PATCH bpf-next] libbpf: don't allocate 16M for log buffer by default Andrii Nakryiko
2020-03-24 23:59 ` Stanislav Fomichev
2020-03-25 0:08 ` Andrii Nakryiko
2020-03-25 9:54 ` Daniel Borkmann
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