From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1425968AbeCBJup (ORCPT ); Fri, 2 Mar 2018 04:50:45 -0500 Received: from mga18.intel.com ([134.134.136.126]:52412 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1424456AbeCBJuk (ORCPT ); Fri, 2 Mar 2018 04:50:40 -0500 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,411,1515484800"; d="scan'208";a="35379315" Date: Fri, 2 Mar 2018 17:41:40 +0800 From: "Du, Changbin" To: "Rafael J. Wysocki" Cc: "Du, Changbin" , Rafael Wysocki , Linux PM , Steven Rostedt , Ingo Molnar , Linux Kernel Mailing List Subject: Re: [PATCH v2] tracing/power: Polish the tracepoints cpu_idle and cpu_frequency Message-ID: <20180302094140.ncypewkdg6g6rs2g@intel.com> References: <1519809638-24248-1-git-send-email-changbin.du@intel.com> <20180301022719.xyfcu5tpmadjxbut@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20171027-42-ad8712 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > >> That rather isn't the case if negative values are ever passed to the > >> tracepoint, right? > >> > > yes. > >> Which seems to be the reason why you want to make this change, isn't it? > >> > > yes, to improve readability. > > > >> So maybe fix the code using the tracepoint(s) to avoid passing > >> negative values to it(them)? > > For cpu_idle event, [0, CPUIDLE_STATE_MAX) are used to index the idle state arrary, > > so I think a appropriate value for PWR_EVENT_EXIT is -1 (defined in include/trace/events/power.h). > > Or do you have a better idea? Thanks! > > Sorry, I'm not sure what you mean. > > I'm saying that the code using the CPU PM tracepoints is not expected > to pass -1 as the CPU number to them. IOW, neither -1 nor its UL > representation should ever appear in the output of these tracepoints. > If that happens, it is a problem with the code using the tracepoints > which needs to be fixed. Users should not see any of these values. This patch only changed 'state' field but cpuid. For cpu_idle event, 'state' is singned value, but for cpu_frequency it is unsinged. The cpuid is always unsinged value. So no one passes -1 as CPU number. -- Thanks, Changbin Du