From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f199.google.com (mail-io0-f199.google.com [209.85.223.199]) by kanga.kvack.org (Postfix) with ESMTP id 582696B0069 for ; Sun, 27 Nov 2016 19:58:45 -0500 (EST) Received: by mail-io0-f199.google.com with SMTP id r101so222955777ioi.3 for ; Sun, 27 Nov 2016 16:58:45 -0800 (PST) Received: from mail-io0-x241.google.com (mail-io0-x241.google.com. [2607:f8b0:4001:c06::241]) by mx.google.com with ESMTPS id 184si38785403iou.226.2016.11.27.16.58.44 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 27 Nov 2016 16:58:44 -0800 (PST) Received: by mail-io0-x241.google.com with SMTP id h133so19749523ioe.2 for ; Sun, 27 Nov 2016 16:58:44 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20161127224208.GA31101@dastard> References: <1479926662-21718-1-git-send-email-ross.zwisler@linux.intel.com> <1479926662-21718-4-git-send-email-ross.zwisler@linux.intel.com> <20161124173220.GR1555@ZenIV.linux.org.uk> <20161125024918.GX31101@dastard> <20161125041419.GT1555@ZenIV.linux.org.uk> <20161125070642.GZ31101@dastard> <20161125073747.GU1555@ZenIV.linux.org.uk> <20161127224208.GA31101@dastard> From: Linus Torvalds Date: Sun, 27 Nov 2016 16:58:43 -0800 Message-ID: Subject: Re: [PATCH 3/6] dax: add tracepoint infrastructure, PMD tracing Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Dave Chinner Cc: Al Viro , Ross Zwisler , Linux Kernel Mailing List , Andrew Morton , Christoph Hellwig , Dan Williams , Ingo Molnar , Jan Kara , Matthew Wilcox , Steven Rostedt , "linux-ext4@vger.kernel.org" , linux-fsdevel , linux-mm , "linux-nvdimm@lists.01.org" On Sun, Nov 27, 2016 at 2:42 PM, Dave Chinner wrote: > > And that's exactly why we need a method of marking tracepoints as > stable. How else are we going to know whether a specific tracepoint > is stable if the kernel code doesn't document that it's stable? You are living in some unrealistic dream-world where you think you can get the right tracepoint on the first try. So there is no way in hell I would ever mark any tracepoint "stable" until it has had a fair amount of use, and there are useful tools that actually make use of it, and it has shown itself to be the right trace-point. And once that actually happens, what's the advantage of marking it stable? None. It's a catch-22. Before it has uses and has been tested and found to be good, it's not stable. And after, it's pointless. So at no point does such a "stable" tracepoint marking make sense. At most, you end up adding a comment saying "this tracepoint is used by tools such-and-such". Linus -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org