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Thu, 28 Aug 2025 14:00:27 -0700 (PDT) Received: from ehlo.thunderbird.net ([185.255.128.130]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45b7e7f14bbsm9520155e9.8.2025.08.28.14.00.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 28 Aug 2025 14:00:26 -0700 (PDT) Date: Thu, 28 Aug 2025 18:00:22 -0300 From: Arnaldo Carvalho de Melo To: Steven Rostedt CC: Linus Torvalds , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, x86@kernel.org, Masami Hiramatsu , Mathieu Desnoyers , Josh Poimboeuf , Peter Zijlstra , Ingo Molnar , Jiri Olsa , Arnaldo Carvalho de Melo , Namhyung Kim , Thomas Gleixner , Andrii Nakryiko , Indu Bhagat , "Jose E. Marchesi" , Beau Belgrave , Jens Remus , Andrew Morton , Florian Weimer , Sam James , Kees Cook , Carlos O'Donell Subject: =?US-ASCII?Q?Re=3A_=5BPATCH_v6_5/6=5D_tracing=3A_Show_inode_and_devi?= =?US-ASCII?Q?ce_major=3Aminor_in_deferred_user_space_stacktrace?= User-Agent: Thunderbird for Android In-Reply-To: <20250828165139.15a74511@batman.local.home> References: <20250828180300.591225320@kernel.org> <20250828180357.223298134@kernel.org> <20250828161718.77cb6e61@batman.local.home> <583E1D73-CED9-4526-A1DE-C65567EA779D@gmail.com> <20250828165139.15a74511@batman.local.home> Message-ID: Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On August 28, 2025 5:51:39 PM GMT-03:00, Steven Rostedt wrote: >On Thu, 28 Aug 2025 17:27:37 -0300 >Arnaldo Carvalho de Melo wrote: > >> >I would love to have a hash to use=2E The next patch does the mapping >> >of the inode numbers to their path name=2E It can =20 >>=20 >> The path name is a nice to have detail, but a content based hash is >> what we want, no? >>=20 >> Tracing/profiling has to be about contents of files later used for >> analysis, and filenames provide no guarantee about that=2E > >I could add the build id to the inode_cache as well (which I'll rename >to file_cache)=2E > >Thus, the user stack trace will just have the offset and a hash value >that will be match the output of the file_cache event which will have >the path name and a build id (if one exists)=2E > >Would that work? Probably=2E This "if it is available" question is valid, but since 2016 it's is more o= f a "did developers disabled it explicitly?" If my "googling" isn't wrong, GNU LD defaults to generating a build ID in = ELF images since 2011 and clang's companion since 2016=2E So making it even more available than what the BPF guys did long ago and p= erf piggybacked on at some point, by having it cached, on request?, in some= 20 bytes alignment hole in task_struct that would be only used when profil= ing/tracing may be amenable=2E - Arnaldo=20