From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965888AbbDVPg1 (ORCPT ); Wed, 22 Apr 2015 11:36:27 -0400 Received: from mail-ig0-f180.google.com ([209.85.213.180]:34813 "EHLO mail-ig0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965695AbbDVPgX (ORCPT ); Wed, 22 Apr 2015 11:36:23 -0400 Message-ID: <5537BFF4.1050605@gmail.com> Date: Wed, 22 Apr 2015 09:36:20 -0600 From: David Ahern User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Arnaldo Carvalho de Melo , Steven Rostedt CC: Ron Rechenmacher , Christoph Hellwig , linux-kernel@vger.kernel.org, Arjan van de Ven , Namhyung Kim , Pawel Moll , Stephane Eranian Subject: Re: [PATCH] tracing: Export key trace event symbols References: <55364CF4.2090600@fnal.gov> <20150421132355.GA18161@infradead.org> <55365002.4010707@fnal.gov> <20150421095310.12370f88@gandalf.local.home> <55366609.4020709@fnal.gov> <20150421114931.63fd343d@gandalf.local.home> <5536CDF1.2020801@fnal.gov> <20150421184446.7b63cbec@gandalf.local.home> <55370673.60504@fnal.gov> <20150422085314.1b07e0b7@gandalf.local.home> <20150422144751.GC2316@kernel.org> In-Reply-To: <20150422144751.GC2316@kernel.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/22/15 8:47 AM, Arnaldo Carvalho de Melo wrote: > Em Wed, Apr 22, 2015 at 08:53:14AM -0400, Steven Rostedt escreveu: >> >On Tue, 21 Apr 2015 21:24:51 -0500 >> >Ron Rechenmacher wrote: >>> > >I've looked at the above reference briefly and it appears that user-space >>> > >would be mmapping the buffer read-only. Is that correct? >> > >> >Correct, but I'm sure we could still add something (if it doesn't >> >already exist) to have userspace write into the buffer. Ftrace has that >> >with the trace_marker file. > There is something in the works, I guess Pawell Moll (sp) was working on it, and > David Ahern (CCed) should know, David? > I played around with generating perf events in userspace with the intention of having the userspace events get merged with kernel events during the processing stage, but I did not take it to the point of integrating into perf. This was around October 2013. I got distracted with other topics and have not come back to it. Pawel has a patch that allows userspace to inject events into the stream via ioctl calls. Stephane also injects events for JIT. One of the key requirements is a common time basis (e.g., CLOCK_MONOTONIC or PERF_CLOCK) to be able to merge the events properly. I have a kernel module that exports perf_clock to userspace via clock_gettime; the 4.1 kernel should have the code that allows the clock id to be specified providing a solution to this problem. David