From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <gaetan.rivet@6wind.com> Received: from mail-wm1-f68.google.com (mail-wm1-f68.google.com [209.85.128.68]) by dpdk.org (Postfix) with ESMTP id F1C9E1B184 for <dev@dpdk.org>; Sat, 6 Oct 2018 00:05:28 +0200 (CEST) Received: by mail-wm1-f68.google.com with SMTP id 185-v6so3181722wmt.2 for <dev@dpdk.org>; Fri, 05 Oct 2018 15:05:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=6wind-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=kyRKwKDbnOETCb94IzSZVIhGlDWMJ/oLU1Dv86iAX/s=; b=R/BZJfTYUQkrtoXm8c4nFrepBrHBJ2ylf8oH/Kv3Wa/qA1w/iT8A45LLHM7avIPbwL sroy7g/qxQL2LXiPq68RPzwxdYCPr87Vo/hoFczKAgAMAE1QhLmoyGzkfIyTSxVVr7jm qDyiJjg9p+onFONhQB5gQwS2pckiuY+A6/iWsVYBu4fY5OE3F8KpuQnTvckN6OfvBO4M FZICA4cuqknSf2si4F7AHJ8zo1W5etaEhCvs/Lj91PMUB+JSlg/OoVtrag8/r+/55tr8 CWu+m/zNaH/RRgYXXxi5amK+m4VKg41U/Vc0Vv0eK7ptI9BtqzFs1sxoghLK3aM+kJHG FD3w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to:user-agent; bh=kyRKwKDbnOETCb94IzSZVIhGlDWMJ/oLU1Dv86iAX/s=; b=tx9d/8s74QgbMVj1RtqCukZo6IQfSAlP4ajrHdxRuNjhlehvJqSMHHP19Idgb1E08v DJtjdQ61IvXCRl5MT45x9C6N9FnvSUQhg+hNAVvLhfGxde1i+zbaRpYNpKJmwNebgRsE nVGbiw02AYJrt1t8sOcXiibNXJ8Lyms+suZgmLjQcs/E/4KNRc6aMMTZNUtpYaSlsxM2 HZSZxU6q9O867yrCZur+sFYO+lueucDFobOYAd2Ip27UQ+6+MNRylahhtNwIru4we0fE VLzA+YKwoWO9xkzYU0GJYtz6TVykKADoEv/0SioI0On+zvKEvuHOpClHkeNGO5TT8aZJ BVFg== X-Gm-Message-State: ABuFfoh9XLbiqlV2eg/dnRYKCeqPTkAd8UQlImfq/IP8DgatzYKXYIb6 roNPIUmcASz1IG+9lGQgQJ8HGA== X-Google-Smtp-Source: ACcGV608UK/oMArs5h2LZBMqWQxWB/ITZXqwpZZAlyPK9vqALu4JVdlxvepZ8smbhnwL5CgdigWtsw== X-Received: by 2002:a1c:ed1a:: with SMTP id l26-v6mr9309652wmh.61.1538777128353; Fri, 05 Oct 2018 15:05:28 -0700 (PDT) Received: from bidouze.vm.6wind.com (host.78.145.23.62.rev.coltfrance.com. [62.23.145.78]) by smtp.gmail.com with ESMTPSA id p62-v6sm17371512wrc.97.2018.10.05.15.05.27 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 05 Oct 2018 15:05:27 -0700 (PDT) Date: Sat, 6 Oct 2018 00:05:09 +0200 From: =?iso-8859-1?Q?Ga=EBtan?= Rivet <gaetan.rivet@6wind.com> To: Thomas Monjalon <thomas@monjalon.net> Cc: "Van Haaren, Harry" <harry.van.haaren@intel.com>, "Laatz, Kevin" <kevin.laatz@intel.com>, "dev@dpdk.org" <dev@dpdk.org>, "stephen@networkplumber.org" <stephen@networkplumber.org>, "shreyansh.jain@nxp.com" <shreyansh.jain@nxp.com>, "Richardson, Bruce" <bruce.richardson@intel.com> Message-ID: <20181005220509.lkxhoaamra7legba@bidouze.vm.6wind.com> References: <1535026093-101872-1-git-send-email-ciara.power@intel.com> <20181003173612.67101-1-kevin.laatz@intel.com> <E923DB57A917B54B9182A2E928D00FA65E2E6127@IRSMSX102.ger.corp.intel.com> <4034734.dNxXkqf0MS@xps> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <4034734.dNxXkqf0MS@xps> User-Agent: NeoMutt/20170113 (1.7.2) Subject: Re: [dpdk-dev] [PATCH v2 00/10] introduce telemetry library X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions <dev.dpdk.org> List-Unsubscribe: <https://mails.dpdk.org/options/dev>, <mailto:dev-request@dpdk.org?subject=unsubscribe> List-Archive: <http://mails.dpdk.org/archives/dev/> List-Post: <mailto:dev@dpdk.org> List-Help: <mailto:dev-request@dpdk.org?subject=help> List-Subscribe: <https://mails.dpdk.org/listinfo/dev>, <mailto:dev-request@dpdk.org?subject=subscribe> X-List-Received-Date: Fri, 05 Oct 2018 22:05:29 -0000 On Thu, Oct 04, 2018 at 05:53:53PM +0200, Thomas Monjalon wrote: > 04/10/2018 15:25, Van Haaren, Harry: > > From: Van Haaren, Harry > > > From: Laatz, Kevin > > > > > > > > This patchset introduces a Telemetry library for DPDK Service Assurance. > > > > This library provides an easy way to query DPDK Ethdev metrics. > > > > > > <snip> > > > > > > > Note: We are aware that the --telemetry flag is not working for meson > > > > builds, we are working on it for a future patch. Despite opterr being set > > > > to 0, --telemetry said to be 'unrecognized' as a startup print. This is a > > > > cosmetic issue and will also be addressed. > > > > > > > > --- > > > > v2: > > > > - Reworked telemetry as part of EAL instead of using vdev (Gaetan) > > > > - Refactored rte_telemetry_command (Gaetan) > > > > - Added MAINTAINERS file entry (Stephen) > > > > - Updated docs to reflect vdev to eal rework > > > > - Removed collectd patch from patchset (Thomas) > > > > - General code clean up from v1 feedback > > > > > > > > > Hi Gaetan, Thomas, Stephen and Shreyansh! > > > > > > > > > goto TL_DR; // if time is short :) > > > > > > > > > In this v2 patchset, we've reworked the Telemetry to no longer use the vdev > > > infrastructure, instead having EAL enable it directly. This was requested as > > > feedback to the v1 patchset. I'll detail the approach below, and highlight > > > some issues we identified while implementing it. > > > > > > Currently, EAL does not depend on any "DPDK" libraries (ignore kvargs etc > > > for a minute). > > > Telemetry is a DPDK library, so it depends on EAL. In order to have EAL > > > initialize > > > Telemetry, it must depend on it - this causes a circular dependency. > > > > > > This patchset resolves that circular dependency by using a "weak" symbol for > > > telemetry init, and then the "strong" version of telemetry init will replace > > > it when the library is compiled in. > > > > Correction: we attempted this approach - but ended up adding a TAILQ of library > > initializers functions to EAL, which was then iterated during rte_eal_init(). > > This also resolved the circular-dependency, but the same linking issue as > > described below still exists. > > > > So - the same question still stands - what is the best solution for 18.11? > > > > > > > Although this *technically* works, it > > > requires > > > that applications *LINK* against Telemetry library explicitly - as EAL won't > > > pull > > > in the Telemetry .so automatically... This means application-level build- > > > system > > > changes to enable --telemetry on the DPDK EAL command line. > > > > > > Given the complexity in enabling EAL to handle the Telemetry init() and its > > > dependencies, I'd like to ask you folks for input on how to better solve > > > this? > > First, the telemetry feature must be enabled via a public function (API). > The application can decide to enable the feature at any time, right? > If the application wants to enable the feature at initialization > (and considers user input from the command line), > then the init function has a dependency on telemetry. > Your dependency concern is that the init function (which is high level) > is in EAL (which is the lowest layer in DPDK). > > I think the command line should not be managed directly by EAL. > My suggestion in last summit was to move this code in a different library. > We should also move the init function(s) to a new high level library. Part of the proposed solution here is to add a thin layer in EAL to register new parameters. I think this could kickstart what you want to do. -- Gaëtan Rivet 6WIND