From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CBE39C43381 for ; Fri, 15 Feb 2019 17:40:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 95C07222BE for ; Fri, 15 Feb 2019 17:40:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550252428; bh=lreoIhKhqt95ydEmV/ZvnxPIBxtK+WuOuVWQ4ti4bYg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=lxucvbuLVk93HTfAt5YOOcJCz7ERIJ4+LH62ojlkY4xKBRK07OI9aLZxXOILrrrwv 6kwhDut7y26wI6b0o0S+Yj0wIQLHf2eW0bpdf8K5WW2k2mXQ2REChiKvmQ66z3DEPy HBxqIGeoFnyzLKLuj6wxVG3twa1g7wSpn0/CvoSg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729974AbfBORk1 (ORCPT ); Fri, 15 Feb 2019 12:40:27 -0500 Received: from mail.kernel.org ([198.145.29.99]:60500 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725939AbfBORk0 (ORCPT ); Fri, 15 Feb 2019 12:40:26 -0500 Received: from quaco.ghostprotocols.net (unknown [190.15.121.82]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7CDD021927; Fri, 15 Feb 2019 17:40:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550252425; bh=lreoIhKhqt95ydEmV/ZvnxPIBxtK+WuOuVWQ4ti4bYg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=G23YUzjHkvcXBGrmtCYoAhdlf6/nGCiG/a4RClxKTxQUrfyGDyFKb2/xZ4rcjiKtY EoHY1sMAA65dznykSDWko48l6udXjwl1ffFJI4KHYSiP/khOZ5qKjdZGywHJCZUdH7 GLD0Qcdj1f9dS0sIup0MPHRgBQYvZtNMB+8+g7Gk= Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id ACFAD410D5; Fri, 15 Feb 2019 14:40:22 -0300 (-03) Date: Fri, 15 Feb 2019 14:40:22 -0300 From: Arnaldo Carvalho de Melo To: Song Liu , Jiri Olsa , Stephane Eranian Cc: Netdev , linux-kernel , Alexei Starovoitov , "daniel@iogearbox.net" , Kernel Team , "peterz@infradead.org" , "namhyung@kernel.org" Subject: Re: [PATCH v2 perf,bpf 08/11] perf, bpf: save btf information as headers to perf.data Message-ID: <20190215174022.GF31177@kernel.org> References: <20190214235624.2579307-1-songliubraving@fb.com> <20190215000010.2590505-1-songliubraving@fb.com> <20190215000010.2590505-7-songliubraving@fb.com> <20190215142643.GC5784@redhat.com> <164D19ED-EA72-4A56-8259-FCF13894B183@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <164D19ED-EA72-4A56-8259-FCF13894B183@fb.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Fri, Feb 15, 2019 at 05:25:01PM +0000, Song Liu escreveu: > > On Feb 15, 2019, at 6:26 AM, Arnaldo Carvalho de Melo wrote: > > Em Thu, Feb 14, 2019 at 04:00:09PM -0800, Song Liu escreveu: > >> This patch enables perf-record to save btf information as headers to > >> perf.data A new header type HEADER_BTF is introduced for this data. > > Wouldn't it be better for this HEADER_BTF to be introduced > > already as an user space event, Song, see: > > tools/perf/util/event.h > > and: > > tools/perf/util/event.c > > perf_event__synthesize_cpu_map() > BTF would be short living for short living BPF programs. I guess > saving them as header is easier than merging them with samples. > What's the benefit of saving them as user space events? When we work with pipe mode, i.e.: perf record -o - | perf report -i - and other combinations (with 'perf script', 'perf inject', etc), we need a way to pass the headers to the other side, and the way was via user space events. This is something Stephane and Jiri have been discussing recently, probably they have more justifications, Stephane, Jiri? - Arnaldo