From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) (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 66A553815F0; Fri, 10 Jul 2026 19:14:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.17 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783710851; cv=none; b=kIQ3oGwGFduEv1eldF5/a++xqJxi5ePOeIfFNR/z1hfAmMc0dsD9SU6vUdDnof+rIRdBDPY2xg/hLiJbqLNGxllaIZfSc2nmL89hj/2QyhkRNeYoTtQ54r65UwxrsRHHMWbw0BsHjL2V3X+gHX37PMz5WMEvTudVZ0xoonCD5DI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783710851; c=relaxed/simple; bh=100S/dvlLVz4p4G++LneVn45QELJa3UerG7xWrUk7mQ=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=PmVlcbak5VgcWnuBQE/eUbOczQV6SsL8NCrq+1lDxWpLQw0NO3LizQce7O69ESx6xyjmI5e6TkPPZ7oC3B6j9twqqsrKQypvNnI81NZY1gDnd2jjOFB5rkltsaVJT4S7q67tqAt9vG5w3KMJjATcCjRdxyQVnBIEI9C4kgfKyd8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; arc=none smtp.client-ip=216.40.44.17 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Received: from omf03.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay06.hostedemail.com (Postfix) with ESMTP id E29631C8C88; Fri, 10 Jul 2026 19:14:07 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf03.hostedemail.com (Postfix) with ESMTPA id C7B986000A; Fri, 10 Jul 2026 19:14:05 +0000 (UTC) Date: Fri, 10 Jul 2026 15:14:15 -0400 From: Steven Rostedt To: Li Pengfei Cc: mhiramat@kernel.org, mathieu.desnoyers@efficios.com, mark.rutland@arm.com, linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org, zhangbo56@xiaomi.com, lipengfei28@xiaomi.com Subject: Re: [RFC PATCH v4 0/3] trace: stack trace deduplication for ftrace ring buffer Message-ID: <20260710151415.726a8c82@gandalf.local.home> In-Reply-To: <20260706063154.1947674-1-lipengfei28@xiaomi.com> References: <20260616064119.438063-1-lipengfei28@xiaomi.com> <20260706063154.1947674-1-lipengfei28@xiaomi.com> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-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 X-Rspamd-Server: rspamout01 X-Rspamd-Queue-Id: C7B986000A X-Stat-Signature: 77d75e1qt5h5n87q6mxxu6ssyurcx4hg X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX19g3eCGWomfAmc0thjoqp/ZFmQvBCDmU7I= X-HE-Tag: 1783710845-904239 X-HE-Meta: U2FsdGVkX1+fAfT6kjfwIrmi59odxYDgkBCCIl5h3kiKYSMT8DU3maQCuq+SF4LSh2OrWSggL+vi0fEjQmeaC3BCju5DuHPcWLGQE+i2ne2PNUS3V2vzlHMKS1t1wmyou89seSrQ2SKDDyGfbBFEu9IfFtqJU2CqyzL5tdCE6fR2Rp/lx/MzEtxB86Z3MYRKZfjHr8MGCr0pabolWVikNnqMSPdukYYr3aRek9MyaJGOMYiQnuiZfpKbvF7lJxG89gqVDW+tzaRyAPEohbpoNQFjcqQJfNZ5fUr4021pviUOx/yCNVwtxR+Qz3vry/nxoFZoi1zZZzSZjSgzXW9ocKJmWdzyruMHdc8458JYFa5IhfRfH59nOs2JhcYJc8Hsd5lFbGwtUMI= On Mon, 6 Jul 2026 14:31:54 +0800 Li Pengfei wrote: > From: Pengfei Li > > Hi Steven, Masami, > > Gentle ping on this v4 series now that the 7.2 merge window has settled. > > I'd especially value a quick steer on the two design questions from the > cover letter, since they shape how I respin: > > 1. Eager vs lazy allocation of the element pool (~8 MB at the default > bits=14 when CONFIG_FTRACE_STACKMAP=y, whether or not userspace ever > enables the option). Is eager allocation acceptable, or should v5 > switch to lazy allocation on the first 'echo 1 > options/stackmap'? > > 2. Whether to introduce the stack_map_bin binary interface now, or ship > the text stack_map interface first and add the binary export once > trace-cmd / libtraceevent integration is designed. > > Happy to respin in either direction. Full series for reference: > > https://lore.kernel.org/all/20260616064119.438063-1-lipengfei28@xiaomi.com/ Sorry for the late reply. I just started a new job (on 6/15) and spent the first two weeks focused on that. I'm just catching up now. Note, I tried out this patch set with function tracing on lock functions: trace-cmd start -p function -O stackmap --func-stack -l '*lock*' And wow! it grows pretty quickly # cat /sys/kernel/tracing/stack_map | wc 326593 708742 10979376 Anyway, I do like the idea and I may even use this to help do user space stack traces. But I will have to take a deeper dive into it, which I will hopefully have some time next week to do so. But if not next week, perhaps within the next month. I just letting you know that I'm not ignoring you. I'm just a bit behind. Thanks, -- Steve