Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757070AbdIHTmH (ORCPT ); Fri, 8 Sep 2017 15:42:07 -0400 Received: from mga07.intel.com ([134.134.136.100]:41080 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757010AbdIHTlp (ORCPT ); Fri, 8 Sep 2017 15:41:45 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.42,363,1500966000"; d="scan'208";a="309613223" Message-ID: <1504899702.5276.14.camel@tzanussi-mobl.amr.corp.intel.com> Subject: Re: [PATCH v2 33/40] tracing: Add hist trigger support for variable reference aliases From: Tom Zanussi To: Steven Rostedt Cc: tglx@linutronix.de, mhiramat@kernel.org, namhyung@kernel.org, vedang.patel@intel.com, bigeasy@linutronix.de, joel.opensrc@gmail.com, joelaf@google.com, mathieu.desnoyers@efficios.com, baohong.liu@intel.com, linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org Date: Fri, 08 Sep 2017 14:41:42 -0500 In-Reply-To: <20170908150955.2ea9351e@gandalf.local.home> References: <35c0e47907c9acaa847c83ad0ec3af0092cde250.1504642143.git.tom.zanussi@linux.intel.com> <20170908150955.2ea9351e@gandalf.local.home> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4 (3.10.4-4.fc20) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 838 Lines: 24 On Fri, 2017-09-08 at 15:09 -0400, Steven Rostedt wrote: > On Tue, 5 Sep 2017 16:57:45 -0500 > Tom Zanussi wrote: > > > Add support for alias=$somevar where alias can be used as > > onmatch($alias). > > This change log is very lacking. What exactly is the purpose of alias? > > Sounds like the variable is going undercover. > This was a feature added at the request of a user, who wanted more flexibility in making naming clearer in certain cases e.g.: # echo 'hist:keys=next_pid:new_lat=$common_timestamp.usecs' > /sys/kernel/debug/tracing/events/sched/sched_switch/trigger # echo 'hist:keys=pid:latency=$new_lat:onmatch(sched.sched_switch).wake2($latency,pid)' > /sys/kernel/debug/tracing/events/synthetic/wake1/trigger I'll add a better description and exampe to the change log for this. Tom