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Tue, 16 Dec 2025 15:38:29 -0800 (PST) Message-ID: Subject: Re: [PATCH bpf-next v9 04/10] libbpf: Optimize type lookup with binary search for sorted BTF From: Eduard Zingerman To: Donglin Peng , ast@kernel.org, andrii.nakryiko@gmail.com Cc: zhangxiaoqin@xiaomi.com, ihor.solodrai@linux.dev, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, pengdonglin , Alan Maguire Date: Tue, 16 Dec 2025 15:38:26 -0800 In-Reply-To: <20251208062353.1702672-5-dolinux.peng@gmail.com> References: <20251208062353.1702672-1-dolinux.peng@gmail.com> <20251208062353.1702672-5-dolinux.peng@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-2.fc42) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Mon, 2025-12-08 at 14:23 +0800, Donglin Peng wrote: [...] Lgtm, one question below. > static __s32 btf_find_by_name_kind(const struct btf *btf, int start_id, > const char *type_name, __u32 kind) > { > - __u32 i, nr_types =3D btf__type_cnt(btf); > + const struct btf_type *t; > + const char *tname; > + __s32 idx; > + > + if (start_id < btf->start_id) { > + idx =3D btf_find_by_name_kind(btf->base_btf, start_id, > + type_name, kind); > + if (idx >=3D 0) > + return idx; > + start_id =3D btf->start_id; > + } > =20 > - if (kind =3D=3D BTF_KIND_UNKN || !strcmp(type_name, "void")) > + if (kind =3D=3D BTF_KIND_UNKN || strcmp(type_name, "void") =3D=3D 0) > return 0; > =20 > - for (i =3D start_id; i < nr_types; i++) { > - const struct btf_type *t =3D btf__type_by_id(btf, i); > - const char *name; > + if (btf->sorted_start_id > 0) { > + __s32 end_id =3D btf__type_cnt(btf) - 1; > + > + /* skip anonymous types */ > + start_id =3D max(start_id, btf->sorted_start_id); > + idx =3D btf_find_by_name_bsearch(btf, type_name, start_id, end_id); > + if (unlikely(idx < 0)) > + return libbpf_err(-ENOENT); > + > + if (unlikely(kind =3D=3D -1)) > + return idx; > + > + t =3D btf_type_by_id(btf, idx); > + if (likely(BTF_INFO_KIND(t->info) =3D=3D kind)) > + return idx; > + > + for (idx++; idx <=3D end_id; idx++) { > + t =3D btf__type_by_id(btf, idx); > + tname =3D btf__str_by_offset(btf, t->name_off); > + if (strcmp(tname, type_name) !=3D 0) > + return libbpf_err(-ENOENT); > + if (btf_kind(t) =3D=3D kind) ^^^^^^^^^^^^^^^^^^^ Is kind !=3D -1 check missing here? > + return idx; > + } > + } else { > + __u32 i, total; > =20 > - if (btf_kind(t) !=3D kind) > - continue; > - name =3D btf__name_by_offset(btf, t->name_off); > - if (name && !strcmp(type_name, name)) > - return i; > + total =3D btf__type_cnt(btf); > + for (i =3D start_id; i < total; i++) { > + t =3D btf_type_by_id(btf, i); > + if (kind !=3D -1 && btf_kind(t) !=3D kind) > + continue; > + tname =3D btf__str_by_offset(btf, t->name_off); > + if (tname && strcmp(tname, type_name) =3D=3D 0) Nit: no need for `tname &&` part, as we found out. > + return i; > + } > } > =20 > return libbpf_err(-ENOENT); > } > =20 > +/* the kind value of -1 indicates that kind matching should be skipped *= / > +__s32 btf__find_by_name(const struct btf *btf, const char *type_name) > +{ > + return btf_find_by_name_kind(btf, btf->start_id, type_name, -1); > +} > + > __s32 btf__find_by_name_kind_own(const struct btf *btf, const char *type= _name, > __u32 kind) > { [...]