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Thu, 23 Oct 2025 15:32:19 -0700 (PDT) Message-ID: <580ec956067975acbf18d354564be3459503ed63.camel@gmail.com> Subject: Re: [RFC bpf-next 00/15] support inline tracing with BTF From: Eduard Zingerman To: Alan Maguire , ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org Cc: martin.lau@linux.dev, acme@kernel.org, ttreyer@meta.com, yonghong.song@linux.dev, song@kernel.org, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, qmo@kernel.org, ihor.solodrai@linux.dev, david.faust@oracle.com, jose.marchesi@oracle.com, bpf@vger.kernel.org Date: Thu, 23 Oct 2025 15:32:16 -0700 In-Reply-To: <20251008173512.731801-1-alan.maguire@oracle.com> References: <20251008173512.731801-1-alan.maguire@oracle.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-1.fc42) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2025-10-08 at 18:34 +0100, Alan Maguire wrote: > The Linux kernel is heavily inlined. As a result, function-focused > observability means it can be difficult to map from code to system > behaviour when tracing. A large number of functions effectively > "disappear" at compile-time; approximately 100,000 are inlined to > 443,000 sites in the gcc-14-built x86_64 kernel I have been testing > with for example. This greatly outnumbers the number of available > functions that were _not_ inlined. This disappearing act has > traditionally been carried out on static functions but with > Link-Time Optimization (LTO) non-static functions also become eligible > for such optimization. I looked at patches 1-12 and at pahole changes. Overall the changes make sense to me, it's great that this is finally moving forward. Left some minor comments in the thread and on the github. Could you please post pahole changes to the mailing list, to facilitate wider discussion? (I'd like Ihor to take a look at the btf_encoder). [...]