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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,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 E8E72C282DE for ; Wed, 5 Jun 2019 07:22:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BE4E22075C for ; Wed, 5 Jun 2019 07:22:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ZuyN59KQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726538AbfFEHW5 (ORCPT ); Wed, 5 Jun 2019 03:22:57 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:55980 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726086AbfFEHW5 (ORCPT ); Wed, 5 Jun 2019 03:22:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=tbIQe82KRWXfpj+AU7ijiA93IgD+ePBUN61009rIGNs=; b=ZuyN59KQFzxjL7oWCjg0GpmXv +lpdH2TaYGNV/c9WX6uV507J13v+WuIJfu8Cxnahf7vEBdqvOoYu7sfDT5nr71ZkOh9Xhzd4u3ivC 3eFW5Rwr53aRQ7/RTItN6g33vv+d5Fihe46bSy/EOIpQjUIOZcPdKIa1EKRms40OjA3vyPsSJi5v8 GSB2Ixef9VSzk2ZyhA/Jpdf/gfsnWEI1GP75s4uqUsv2+EWi2o07toI1ftj2cSeg8Fca+S/Ds94U7 N+oILRkjEXsMFKpFDR/YKaJIkWnM+sQDbRMJ/Se4pebfFmOJmQB4q4rCnY+o0Sb5rIYpyR1yk92BE qbry4b0pg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hYQFh-0007oa-Qb; Wed, 05 Jun 2019 07:22:29 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 7F197207A17DB; Wed, 5 Jun 2019 09:22:27 +0200 (CEST) Date: Wed, 5 Jun 2019 09:22:27 +0200 From: Peter Zijlstra To: Christoph Hellwig Cc: Qais Yousef , Ingo Molnar , Steven Rostedt , linux-kernel@vger.kernel.org, Pavankumar Kondeti , Sebastian Andrzej Siewior , Uwe Kleine-Konig , Dietmar Eggemann , Quentin Perret Subject: Re: [PATCH v3 0/6] sched: Add new tracepoints required for EAS testing Message-ID: <20190605072227.GI3419@hirez.programming.kicks-ass.net> References: <20190604111459.2862-1-qais.yousef@arm.com> <20190605061748.GA20661@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190605061748.GA20661@infradead.org> 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 On Tue, Jun 04, 2019 at 11:17:48PM -0700, Christoph Hellwig wrote: > > The following patches add the bare minimum tracepoints required to perform EAS > > testing in Lisa[1]. > > What is EAS? Whhy is "Lisa" not part of the patch submission? > submission. > > > It is done in this way because adding new TRACE_EVENTS() is no longer accepted > > AFAIU. > > Huh? We keep adding trace events all the time. And they actually > are useful because they are testable. They also form an implicit API/ABI with userspace, and I've been bitten by that crap before. No more tracepoints. IIRC viro is also not having tracepoints in the vfs. > This series on the other hand adds exports not used in tree, which is > a big no-go. I much prefer a few unused exports that expose data in a controlled fashion than commit to an implicit ABI through tracepoints. By keeping it all in kernel, we're punting to the no-in-kernel-ABI rule. Basically nobody gives a crap if we break (out-of-tree) modules, but the moment we break something userspace we're fscked.