From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 720F38F7D; Wed, 22 Jan 2025 21:38:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737581892; cv=none; b=RQ4HwW01vX/YRzhaLj4SwKM35QrBeG1nR7ykPxUsyX6XGj9PY8cdgzf6/tvLSTclHSwY2fiwRswBmosIZftLJZcfprVruJk3TYPz0whKwmFsz7cgbDSmzb3oonpTMok2TqA7OR9Pc/pWp+tKmrX8o7dMnpA31dH3Zie6qccTMGc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737581892; c=relaxed/simple; bh=nsa82N+UqX5eUkDvsBsM38qybveCYzz7Y/ICGZXEC8U=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=R1e9kLHOdfQqMwYRQYgVCMvKGkNxhxIAw8HqpuB4ipEa6ZvapSonsS0BnclPmYWltLmVLUJZRB7twSiiS+tbb5NHfGdbidpMuXe1K3ORD7RAqP9FJ5oM3DPl2Jsz36JATrmMqyEPAdcG6B7DLhufphtrgvbxM8j6Fg2tXVKgZz4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JI91gAQ3; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JI91gAQ3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 53A02C4CED2; Wed, 22 Jan 2025 21:38:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737581892; bh=nsa82N+UqX5eUkDvsBsM38qybveCYzz7Y/ICGZXEC8U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=JI91gAQ3Mikl+ahGA4pYV+Iy9w+Xys7F1IwWQc+cpixaXLs9nAXUJIoyAnQgXszjF h97W5G0piJR5rDmfJYf/O53bVuaowS5LD2H1LslhpZocMiEJ5UuCpaWjWKmu0EGDs7 63t9+J+K6DUY8HIFyngRu+IYUXvns4FCrtvkmgfrpWEDhSb4xZ1TYd1ocBB4P7ORAv s8tFe1vMYjsp4QwaIGyH2dTkbmd11c7QpjKi3hdBhy53/LCzE4Ns39/fbLkmSG7zQx 9IYFfafSnrdgfa1Q+aeDAoY/qmWYvX+GUFQyDrQO6MzeCM1Nqm5scQJbci1A6Keajl COG0Gn+JHYf0g== Date: Wed, 22 Jan 2025 13:38:09 -0800 From: Josh Poimboeuf To: Peter Zijlstra Cc: x86@kernel.org, Steven Rostedt , Ingo Molnar , Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org, Indu Bhagat , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , linux-perf-users@vger.kernel.org, Mark Brown , linux-toolchains@vger.kernel.org, Jordan Rome , Sam James , linux-trace-kernel@vger.kernel.org, Andrii Nakryiko , Jens Remus , Mathieu Desnoyers , Florian Weimer , Andy Lutomirski , Masami Hiramatsu , Weinan Liu Subject: Re: [PATCH v4 28/39] unwind_user/deferred: Add deferred unwinding interface Message-ID: <20250122213809.wcpmpvexg3gmzsoq@jpoimboe> References: <6052e8487746603bdb29b65f4033e739092d9925.1737511963.git.jpoimboe@kernel.org> <20250122133730.GQ7145@noisy.programming.kicks-ass.net> 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=utf-8 Content-Disposition: inline In-Reply-To: <20250122133730.GQ7145@noisy.programming.kicks-ass.net> On Wed, Jan 22, 2025 at 02:37:30PM +0100, Peter Zijlstra wrote: > On Tue, Jan 21, 2025 at 06:31:20PM -0800, Josh Poimboeuf wrote: > > +/* > > + * The context cookie is a unique identifier which allows post-processing to > > + * correlate kernel trace(s) with user unwinds. The high 12 bits are the CPU > > s/12/16/ ? Oops. Code is right, comment is wrong. > > > + * id; the lower 48 bits are a per-CPU entry counter. > > + */ > > +static u64 ctx_to_cookie(u64 cpu, u64 ctx) > > +{ > > + BUILD_BUG_ON(NR_CPUS > 65535); > > + return (ctx & ((1UL << 48) - 1)) | (cpu << 48); > > +} -- Josh