From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fhigh-a5-smtp.messagingengine.com (fhigh-a5-smtp.messagingengine.com [103.168.172.156]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0EFDF1A2C04 for ; Sun, 21 Jun 2026 06:34:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=103.168.172.156 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782023663; cv=none; b=WtEcSI8JepiskEfUvxBI0gqQx2Ca87SFI9u6Wpkz79/EKjKvFifdwJhSpkVaW1DfkrbZOMCz4DfsUGzIwWjEVzaVwQdNrttlv8Vozkt0KvP9wHy++GjsdIhMnu1g0c+P7oQiJUUWNt9bl1idk5DoEFyBpqcCZn6DNhz/Hrez/lA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782023663; c=relaxed/simple; bh=0wrdKx9elPOkQLTxEMGz503FFl5gnIq8NdJ4SuLB3yE=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=ltSeeUPxnERmFkOk9cpZQqqoANj6dQtiaho7E/570P45L1IAmQVHZc7nYbvdGmkdIXrtqrJafow/R3aJd1p8u4QCFWDKNPk6a11hy10RsgqJy7zEwsod+/OhmKbqYrJJAic4+AdkOUoYatrZghH9XJ4BTRtHgS+xKW2jow6soKA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=rostedt.org; spf=pass smtp.mailfrom=rostedt.org; dkim=pass (2048-bit key) header.d=rostedt.org header.i=@rostedt.org header.b=AbrylZyK; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b=d+CBYrRA; arc=none smtp.client-ip=103.168.172.156 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=rostedt.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=rostedt.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=rostedt.org header.i=@rostedt.org header.b="AbrylZyK"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="d+CBYrRA" Received: from phl-compute-02.internal (phl-compute-02.internal [10.202.2.42]) by mailfhigh.phl.internal (Postfix) with ESMTP id 1A9CF14000E8; Sun, 21 Jun 2026 02:34:20 -0400 (EDT) Received: from phl-frontend-04 ([10.202.2.163]) by phl-compute-02.internal (MEProxy); Sun, 21 Jun 2026 02:34:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rostedt.org; h= cc:cc:content-transfer-encoding:content-type:content-type:date :date:from:from:in-reply-to:in-reply-to:message-id:mime-version :references:reply-to:subject:subject:to:to; s=fm2; t=1782023660; x=1782110060; bh=chU/Ua1iXzawlorjuubIHCjude7rOzDNZZgpzEd+vAc=; b= AbrylZyKz0dcqiHo+QEkwoC45c+JRm68PAEwff6mNauHSzncc+m8n176ZyT5FgV4 rslkVVGjcoTDweCgpbCIY2IXYpAsQ0kRudWAMx/ktRLPnVhSpuqcTaqCllB7CrKz e0CUT3KlloH9h1KzkMX49N8KH1VEKQHlYJay/vQuGUqYp8wy3NGmnBUxXHCqexcK C/blCMoOvzdSQ2b5kkqN9U40QMO+HIxURq327ou+OcFrAq4oo8D5mB/4B1J1SAWQ 1OGeJ4nW5CBkUjLPEMoKIzo+7d3dUznO+L+TXOon9UUgHfrACZGwd+93GK+yGVFR WLFhM8c6ur9rDJ3xhhvlMQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding :content-type:content-type:date:date:feedback-id:feedback-id :from:from:in-reply-to:in-reply-to:message-id:mime-version :references:reply-to:subject:subject:to:to:x-me-proxy :x-me-sender:x-me-sender:x-sasl-enc; s=fm1; t=1782023660; x= 1782110060; bh=chU/Ua1iXzawlorjuubIHCjude7rOzDNZZgpzEd+vAc=; b=d +CBYrRAReC31HwS9xyoiSNpxH4Ra3ZkRt1EG94dfDYJh6XlZZdiEOXJeT46/msRh 62uLBRvEZK7/QPQsyjNeipDIdwZTT/c+fcTZ2Bkef7G42bQykJhvBiUzKhFSAM3Q PQXiA0n018WkLcd5OIlOLHShUUJfYGLfHc/DP5Y+CuWtdGsf8aVTsS1zXbD362O2 ni/vP28usiiXVJNLjZYouZ5MrBQD/heyJNZLtsILwP/iXsH9PbkkbxVcKQzeNT2Y NrapLVh98cVt+vsxE5xaUzCSfDMF4ZHmA9YMyXVDZ2y85+iBATRTMZBzyNa6dB4L 6UbcQYKVg8uDckyF/L9og== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTFI0erFCAdQWNRey6mqrPyUUd0RdUqMLJBCyBjA6wZ4mcU4CCNC5XKfb9J6UxHp/r j3e1YNnjBAi6zfOgLdA2WF4puGjMeJ4XVica2n3ulAgUwP2iwZ0CkiJ6zHGxS6aOvEKZhs apF4XRBQHUhpCuTMH3ifO500FqbLwduWmTMKHFfBbTGVzDGoMOKQOU0UoiHBFj+6xBfYFi Sx9mhJjwm5R44i73X9MuXY40HGiGJonD+3HD5cg8XealHl7fGueV5Q9K79SNbCbYXmGoUd kYBIVmSeVDbUa88VY82v4rK06QYi6b0T1kq5ywzFetXgqBDqnMUDkA7yTFaXFxKoXphIMX I476OS8rzlBd1U1/SwuExpIXwkOwKn8aRHFsFmXeQGmdLrnOZYaMBS/Ye6Em1rPI4XqJsK ON5dITxa97QNM6xhP2b1ailiCry+HCq14dxmBeydcl96N9ljjeZxHCzJRmG1tLd1DshZ/b nHf72n3xvOtkfoG2JiKf4kU5KWPVTtjaM5l87tdAuaAqAH7/bSRyxI+XgBsvBpDvTQLdIx pX9A5mWvznT0ovDnBdUN7ATzNH5x3HACUa4Aty8MjSXM85uy7nRNz5atXAYgbKxjfwVYuB vXWuKqaDOStxBlFIcnoJCGlh92SIHrjw7RDilkIFz7E7tOhueg8BksmUaHOg X-ME-Proxy: Feedback-ID: id06e481b:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Sun, 21 Jun 2026 02:34:15 -0400 (EDT) Date: Sun, 21 Jun 2026 02:34:12 -0400 From: Steven Rostedt To: Linus Torvalds Cc: Yury Norov , LKML , Masami Hiramatsu , Mathieu Desnoyers , Ao Sun , David Carlier , Karl Mehltretter , Martin Kaiser , Pengpeng Hou , Qian-Yu Lin , Rik van Riel , Rosen Penev , Shuvam Pandey , Vineeth Pillai , Yash Suthar , Yu Peng , Sebastian Andrzej Siewior , Thomas Gleixner , Peter Zijlstra Subject: Re: [GIT PULL] tracing: Updates for 7.2 Message-ID: <20260621023412.2cfab3f0@fedora> In-Reply-To: References: <20260616180122.57a3b426@fedora> <20260619081513.3e4a1fb0@fedora> <20260620181957.115d662c@fedora> <20260620194233.4e1e5d10@fedora> X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sat, 20 Jun 2026 17:18:26 -0700 Linus Torvalds wrote: > > Because no, trace_printk() isn't special. When you have a bug that triggers once every 11 days, due to some strange race, placing trace_printk()s all over to help you narrow down *where* to look is super important. trace_printk() has an extremely low overhead, like 150 ns which keeps the chances of it affecting the races low. Note, the above scenario was real story another kernel developer told me about, but that's besides the point. > > Christ, the only reason *you* think it's so special is because it's > your code and you use it, and the people you interact with use it. Do you know who the people I interact with are? 100s if not 1000s of kernel developers! I get my ideas from going to conferences and talking with people. This isn't me in some silo helping out an internal corporation with their secret sauce. I was unemployed from April 19th to June 15th and in that time I paid my own way to go to LSF/MM/BPF to find out more ways the tracing subsystem can be useful to others! Hang out more at conferences and talk to your kernel's developers and get a better idea of what people use. You interface mostly with top level maintainers. How much are you interfacing with the 1000s of contributors we have? Tracing has been extremely helpful for new developers. I've mentored several. How many new developers have you mentored in the last 5 years? That's a serious question. I don't know if you mentor new developers or not. It would be great if you did. Just last week, someone asked me how I got involved with the Linux kernel. They said, "It's so big and complex, how did you start?". I started looking at the kernel code in 1998. It was much simpler back then. Learning most of the kernel wasn't that difficult compared to starting development today. I only had to learn things as they came into existence. Learning about new features that appear over the years is much easier than coming in fresh and everything is a new feature to learn. > > But that's not because it's special - the common issue is *you*, not > trace_printk. > You already had others tell you that they use trace_printk() for debugging too. It's *not* just me! Ask people. There's been several times I've had people come up to me at conferences and thank me for trace_printk(). Heck, trace_prink() was important enough to be included in eBPF for debugging they programs. > > We're done here. That header gets removed from kernel.h. I told you I'm 100% fine with removing trace_printk.h from kernel.h if you are OK with the Makefile solution I posted. Having a TRACE_PRINTK_DEBUGGING config would not cause any issue for you or others that don't care about it. I believe it's a proper compromise. You seem to act like I'm arguing to keep trace_printk.h in kernel.h after I came up with an alternate solution. Let me add back the question you asked to the very first line of my reply that you went off on: > On Sat, 20 Jun 2026 15:39:25 -0700 > Linus Torvalds wrote: > > > Feel free to try to come up with such a patch. > > > > But honestly, before you do, what is the *advantage* of such a thing? > > For debugging it is really useful. You seem to think that comment was about why to keep trace_printk.h in kernel.h and bother everyone that doesn't use it. No, you asked me what the advantage of having the Makefile solution was, and that was my answer. -- Steve