From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id 0lxmKzVW6WaB7C0AWB0awg (envelope-from ) for ; Tue, 17 Sep 2024 06:13:09 -0400 Authentication-Results: simark.ca; dkim=pass (2048-bit key; unprotected) header.d=lists.lttng.org header.i=@lists.lttng.org header.a=rsa-sha256 header.s=default header.b=kFJLsoxL; dkim-atps=neutral Received: by simark.ca (Postfix, from userid 112) id 912E01E353; Tue, 17 Sep 2024 06:13:09 -0400 (EDT) X-Spam-Checker-Version: SpamAssassin 4.0.0 (2022-12-13) on simark.ca X-Spam-Level: X-Spam-Status: No, score=-11.7 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, RCVD_IN_VALIDITY_CERTIFIED,RCVD_IN_VALIDITY_RPBL,RCVD_IN_VALIDITY_SAFE, URIBL_BLOCKED,URIBL_DBL_BLOCKED_OPENDNS autolearn=ham autolearn_force=no version=4.0.0 Received: from lists.lttng.org (lists.lttng.org [167.114.26.123]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPS id 3BBF71E05C for ; Tue, 17 Sep 2024 06:13:08 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=lists.lttng.org; s=default; t=1726567987; bh=PAAF53DQgaS1yQlK4gDjRZJD4tOCYqusg106eXVvFr0=; h=Date:To:References:Cc:In-Reply-To:Subject:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From:Reply-To:From; b=kFJLsoxLY5ifmkztpnzGwDdTaguRM+ljoNVrIa5V2AsN376S74vsuwbIQ/9vt6uRa HIOzLtijtWVzTyXyCtEM5Vea72/4/stXG8JJ1omW05yiHdV5EoIk5MO+/gdR1pHsJ4 OrpnGjWk7/pQ4XLPr88XFLcpfvHKQzYnP4qP8HI7Uzc0+BM/NvSenevuMN2mLK0xww oeEzMtU6yZGwvndK67kE7VqkTlG/sYVOWEUC7QZ5H9LTTCobP5gv215UwHaIomU/zy YPTiUVeBx/S/+t2Go7olkc06uU0KQtordn54iuMp/9UOuU5VdBjQkL8LhYiA1x9g4+ xOTofkphVugkQ== Received: from lists-lttng01.efficios.com (localhost [IPv6:::1]) by lists.lttng.org (Postfix) with ESMTP id 4X7HfW2sPsz1HbH; Tue, 17 Sep 2024 06:13:07 -0400 (EDT) Received: from smtpout.efficios.com (smtpout.efficios.com [IPv6:2607:5300:203:b2ee::31e5]) by lists.lttng.org (Postfix) with ESMTPS id 4X7HfV3QdKz1Hk8 for ; Tue, 17 Sep 2024 06:13:06 -0400 (EDT) Received: from [IPV6:2001:4bc9:a46:d7de:edc9:fc73:b785:1ddd] (unknown [IPv6:2001:4bc9:a46:d7de:edc9:fc73:b785:1ddd]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4X7HfT0Nbkz1LCq; Tue, 17 Sep 2024 06:13:04 -0400 (EDT) Message-ID: Date: Tue, 17 Sep 2024 12:12:18 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: Akhil Veeraghanta , Akhil Veeraghanta via lttng-dev References: Content-Language: en-US Cc: Simon Marchi , Philippe Proulx In-Reply-To: Subject: Re: [lttng-dev] workqueue tracing symbols X-BeenThere: lttng-dev@lists.lttng.org X-Mailman-Version: 2.1.39 Precedence: list List-Id: LTTng development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Mathieu Desnoyers via lttng-dev Reply-To: Mathieu Desnoyers Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: lttng-dev-bounces@lists.lttng.org Sender: "lttng-dev" On 2024-09-17 02:44, Akhil Veeraghanta via lttng-dev wrote: > Hello, > > We are trying to debug kernel work queue related issues in our system. > And as such, we've turned on workqueue_queue_work, > workqueue_active_work, workqueue_execute_start, workqueue_execute_end. > > The tracepoint itself stores the function pointer which we can look up > from /proc/kallsyms manually. > > We've been struggling to do this automatically, we've tried: > > 1. > Using babeltrace2 to "convert" from lttng to lttng by just editing > the events in place. This doesn't work (atleast as easily) because > the event iterator is const. Augmenting the CTF trace with extra symbolic information using babeltrace2 would be the preferred way. We have examples on how to do it with the debug-info babeltrace2 filter component. CCing Philippe and Simon about this. > > 2. > Loading the kallsyms file with "Configure Symbols" in trace compass > doesn't work either because it doesn't know that it can look up > functions in workqueue events from that file. > > Converting to a text based format like chrome trace and replacing > the fields works, but then we have to use chrome::tracing which > isn't as powerful. > > Before we go any futher modifying trace compass or writing a smarter > parser, is there a way we can trace the workqueues and do the lookup > properly? Fetching the symbol information at tracing time would add a significant overhead in terms of CPU cycles and wasted ring buffer space. Symbol resolution should really be kept to post-processing unless there are really no other options. Thanks, Mathieu > > 3. > > > _______________________________________________ > lttng-dev mailing list > lttng-dev@lists.lttng.org > https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev