From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B89DBC43603 for ; Wed, 18 Dec 2019 12:09:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 953E12146E for ; Wed, 18 Dec 2019 12:09:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726799AbfLRMJI (ORCPT ); Wed, 18 Dec 2019 07:09:08 -0500 Received: from foss.arm.com ([217.140.110.172]:44064 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726029AbfLRMJH (ORCPT ); Wed, 18 Dec 2019 07:09:07 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2C5F930E; Wed, 18 Dec 2019 04:09:07 -0800 (PST) Received: from bogus (e107155-lin.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 290633F6CF; Wed, 18 Dec 2019 04:09:06 -0800 (PST) Date: Wed, 18 Dec 2019 12:09:00 +0000 From: Sudeep Holla To: Jim Quinlan Cc: lukasz.luba@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, mingo@redhat.com, rostedt@goodmis.org, Sudeep Holla Subject: Re: [PATCH 1/2] include: trace: Add SCMI header with trace events Message-ID: <20191218120900.GA28599@bogus> References: <20191216161650.21844-1-lukasz.luba@arm.com> <20191216161650.21844-1-lukasz.luba@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191216161650.21844-1-lukasz.luba@arm.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 16, 2019 at 05:15:54PM -0500, Jim Quinlan wrote: > From: Lukasz Luba > > + > +TRACE_EVENT(scmi_xfer_begin, > + TP_PROTO(u8 id, u8 protocol_id, u16 seq, bool poll), > + TP_ARGS(id, protocol_id, seq, poll), > + > + TP_STRUCT__entry( > + __field(u8, id) > + __field(u8, protocol_id) > + __field(u16, seq) > + __field(bool, poll) > + ), > + > + TP_fast_assign( > + __entry->id = id; > + __entry->protocol_id = protocol_id; > + __entry->seq = seq; > + __entry->poll = poll; > + ), > + > + TP_printk("id=%u protocol_id=%u seq=%u poll=%u", __entry->id, > + __entry->protocol_id, __entry->seq, __entry->poll) > +); > + > +TRACE_EVENT(scmi_xfer_end, > + TP_PROTO(u8 id, u8 protocol_id, u16 seq, u32 status), > + TP_ARGS(id, protocol_id, seq, status), > + > + TP_STRUCT__entry( > + __field(u8, id) > + __field(u8, protocol_id) > + __field(u16, seq) > + __field(u32, status) > + ), > + > + TP_fast_assign( > + __entry->id = id; > + __entry->protocol_id = protocol_id; > + __entry->seq = seq; > + __entry->status = status; > + ), > + > + TP_printk("id=%u protocol_id=%u seq=%u status=%u", __entry->id, > + __entry->protocol_id, __entry->seq, __entry->status) > +); > > Hello, > > When there are multiple messages in the mbox queue, I've found it > a chore matching up the 'begin' event with the 'end' event for each > SCMI msg. The id (command) may not be unique, the proto_id may not be > unique, and the seq may not be unique. I agree on id and proto_id part easily and the seq may not be unique if and only if the previous command has completed. > The combination of the three may not be unique. Not 100% sure on that. I remember one of the issue you reported where OS times out and platform may still be processing it. That's one of the case where seq id may get re-assigned, but now that's fixed and the scenario may not happen. I am trying to understand why you think it is not unique ? > Would it make sense to assign a monotonically increasing ID to each > msg so that one can easily match the two events for each msg? I am not sure if we need to maintain a tracker/counter just for trace purposes. > This id could be the result of an atomic increment and > could be stored in the xfer structure. Of course, it would be one of > the values printed out in the events. > > Also, would you consider a third event, right after the > scmi_fetch_response() invocation in scmi_rx_callback()? I've found > this to be insightful in situations where we were debugging a timeout. > > I'm fine if you elect not to do the above; I just wanted to post > this for your consideration. > I am interested in the scenario we can make use of this and also help in testing it if we add this. I am not against it but I don't see the need for it. -- Regards, Sudeep