From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752715AbbLIIDt (ORCPT ); Wed, 9 Dec 2015 03:03:49 -0500 Received: from mail-wm0-f42.google.com ([74.125.82.42]:37304 "EHLO mail-wm0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751365AbbLIIDs (ORCPT ); Wed, 9 Dec 2015 03:03:48 -0500 Date: Wed, 9 Dec 2015 09:03:43 +0100 From: Ingo Molnar To: Josh Poimboeuf Cc: Arnaldo Carvalho de Melo , Jiri Olsa , Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, Namhyung Kim , Borislav Petkov Subject: Re: [PATCH v2 14/14] perf tools: Move subcommand framework and related utils to libapi Message-ID: <20151209080343.GA14846@gmail.com> References: <0374ac2777cfb277f395de8423d670265400eb1b.1449548395.git.jpoimboe@redhat.com> <20151208181625.GB18433@krava.brq.redhat.com> <20151208184953.GG14846@treble.redhat.com> <20151208190931.GK11564@kernel.org> <20151208191700.GH14846@treble.redhat.com> <20151208194026.GL11564@kernel.org> <20151208214825.GI14846@treble.redhat.com> <20151208222732.GA15864@kernel.org> <20151208230725.GJ14846@treble.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151208230725.GJ14846@treble.redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Josh Poimboeuf wrote: > > > wouldn't necessarily be a clean split. It would also possibly create more > > > room for error for the users of libapi, since there would then be three > > > config interfaces instead of one. > > > > Humm, and now that you talk... libapi was supposed to be just sugar coating > > kernel APIs, perhaps we need to put it somewhere else in tools/lib/ than in > > tools/lib/api/? > > Ah, I didn't realize libapi was a kernel API abstraction library. Shall we put > it in tools/lib/util instead? Yay, naming discussion! ;-) So if this is about abstracting out the (Git derived) command-line option parsing UI and help system, 'util' sounds a bit too generic. We could call it something like 'lib/cmdline', 'lib/options'? The (old) argument against making too finegrained user-space libraries was that shared libraries do have extra runtime costs - this thinking resulted in catch-all super-libraries like libgtk: size /usr/lib/x86_64-linux-gnu/libgtk-3.so.0 text data bss dec hex filename 7199789 57712 15128 7272629 6ef8b5 /usr/lib/x86_64-linux-gnu/libgtk-3.so.0 But in tools/ we typically link the libraries statically so there's no shared library cost to worry about. (Build time linking is a good idea anyway, should we ever want to make use of link-time optimizations. It also eliminates version skew and library compatibility breakage.) The other reason for the emergence of super-libraries was the high setup cost of new libraries: it's a lot easier to add yet another unrelated API to libgtk than to start up a whole new project and a new library. But this setup cost is very low in tools/ - one of the advantage of shared repositories. So I think in tools/lib/ we can continue to do a clean topical separation of libraries, super-libraries are not needed. Thanks, Ingo