From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5D5E641DDE0 for ; Fri, 7 Aug 2026 11:19:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786101575; cv=none; b=mvkmc1LymgyTu0DkNY9qfbjX+12SS35HtFcB+NaYNqUOAyPevP3qoEuJrstQqRJ6ml3NHyO40LlBXgav0hsVmFZVdhmO+AFBvbRlCM1c3hn6zy400HPLk+osbas8TzikKPMur3vMBzA+cAY84D2y19e4SuRdJBVNsXHydmeHCJg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786101575; c=relaxed/simple; bh=UyGvst7gzz8aMp7NaIlca5Hlj4nQIZzAQEyNUPlvs9U=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JfNhNUm/07y8a3jxihRnvtEBTuUcjpORo5eTsyM60cpufgdkxlICYeD09Mg+NGIb4P+OLo19sQUTnUglIEoFne6Y3E+C9nZc6jmBLyrlteX84Up+aWarc5dthYMbc+E1Yq7Yj/fDtghYCgEcHtXdIx0We4vl7geLrC5g7q2V9es= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=pass smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=GLLHEh9B; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="GLLHEh9B" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=XugU5f9n5F8bRW8RWLCJjZoXjblijUIJs+6+P1YYKYA=; b=GLLHEh9Bkt7kMsvaMs+LNTXL8U XUsVeW6lHX6X0JMNAvX3Q3xl8q98g0uw8b5wRpr5lRxdPIqqdKmxsQ5YVjbvOeZAMtFuPxBQB7wQO jqZgKBMyL57jFqmYxPDMZutbb34vqFmISHbfTP6mUqITv9DdUt9R0/pGVHIJtQsm1YS3oWrj42WyI bVg2aWhQ57L5pL6UXGZF2Yo2dxO3WP+ikx0WAF0TOVjLhDwgulMd8QJbnJgsT7/Uang/6o2reW7w5 xloKKV3/r3nBKEslZ1JwaxtJsjuPCQ+rs5hSNo6KKGdPGMRmtsOm3Prio+iynqnZbCDoH0H7Fi1ki ZsqYB5mQ==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.99.1 #2 (Red Hat Linux)) id 1wsIal-00000008tUv-3KmU; Fri, 07 Aug 2026 11:18:24 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 4464A30045A; Fri, 07 Aug 2026 13:18:18 +0200 (CEST) Date: Fri, 7 Aug 2026 13:18:18 +0200 From: Peter Zijlstra To: Ian Rogers Cc: Steven Rostedt , Masami Hiramatsu , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Adrian Hunter , James Clark , Suzuki K Poulose , Mike Leach , Leo Yan , John Garry , Will Deacon , Thomas Gleixner , Dapeng Mi , Ravi Bangoria , Swapnil Sapkal , Thomas Falcon , Thomas Richter , Dmitrii Dolgov <9erthalion6@gmail.com>, Eric Biggers , Zecheng Li , Gabriel Marin , Tengda Wu , Derek Foreman , Tanushree Shah , Ankur Arora , Aaron Tomlin , tanze , Rui Qi , Howard Chu , Chuck Lever , Shimin Guo , Alessio Podda , linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-perf-users@vger.kernel.org, coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org Subject: Re: [RFC PATCH v1 0/8] perf/core, perf/tools: Add PERF_SAMPLE_BUILD_ID_OFFSET support Message-ID: <20260807111818.GN687043@noisy.programming.kicks-ass.net> References: <20260807071818.718751-1-irogers@google.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260807071818.718751-1-irogers@google.com> On Fri, Aug 07, 2026 at 12:18:10AM -0700, Ian Rogers wrote: > This patch series introduces PERF_SAMPLE_BUILD_ID_OFFSET to the > perf_event UAPI and implements full support across both the kernel > and perf tools. > > Background & Motivation: > > In order for perf to translate virtual addresses of samples into > symbols a file and offset within the file are needed. During event > synthesis perf will create mmap events to facilitate the translation > of a virtual address to a file and offset by modelling the address > space of a process. By directly recording in a sample the Build ID of > a file and the offset within it, no synthesis is necessary. The Build > ID and offset as a pair are much larger than a virtual address, so > there is a trade-off between synthesis cost and extra size for > samples. These changes just facilitate Build ID and offset as a choice > for perf samples and the user can have the choice to use it when they > believe it is advantageous. > > In practice perf still needs to map a build ID to a file, so by > default this change keeps synthesis to allow this. It is expected a > user that knows their build IDs, say through debuginfod, will disable > this option with say --synth=no. > > The kernel support uses the existing build ID and offset support used > by BPF stack traces. That is still a giant stinking mess that needs to cleaned up.