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 E5722C2D0C0 for ; Mon, 23 Dec 2019 15:39:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B224D20715 for ; Mon, 23 Dec 2019 15:39:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726874AbfLWPjO (ORCPT ); Mon, 23 Dec 2019 10:39:14 -0500 Received: from foss.arm.com ([217.140.110.172]:46964 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726824AbfLWPjO (ORCPT ); Mon, 23 Dec 2019 10:39:14 -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 8C9491FB; Mon, 23 Dec 2019 07:39:13 -0800 (PST) Received: from [10.37.12.81] (unknown [10.37.12.81]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DA2613F6CF; Mon, 23 Dec 2019 07:39:11 -0800 (PST) Subject: Re: [PATCH 1/2] include: trace: Add SCMI header with trace events To: Jim Quinlan , Sudeep Holla Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, mingo@redhat.com, rostedt@goodmis.org References: <20191216161650.21844-1-lukasz.luba@arm.com> <20191218120900.GA28599@bogus> <7b59a2f1-0786-d24f-a653-76a60c15a8ae@broadcom.com> <7fe599d3-1ce2-1fde-2911-9516a26090b6@arm.com> <9befbc13-ba00-094d-0064-0d97c1ccbb63@broadcom.com> From: Lukasz Luba Message-ID: Date: Mon, 23 Dec 2019 15:39:09 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <9befbc13-ba00-094d-0064-0d97c1ccbb63@broadcom.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/20/19 4:24 PM, Jim Quinlan wrote: > >> Thank you for sharing your experiments and thoughts. I have probably >> similar setup for stressing the communication channel, but I do also >> some wired things in the firmware. That's why I need to measure these >> delays. I am happy that it is useful for you also. >> >> I don't know if your firmware supports 'fast channel', but please keep >> in mind that it is not tracked in this 'transfer_id'. >> This transfer_id in v2 version does not show the real transfers >> to the firmware since there is another path called 'fast channel' or >> 'fast_switch' in the CPUfreq. It is in drivers/firmware/arm_scmi/perf.c >> and the atomic variable is not incremented in that path. Adding it also >> there just for atomic_inc() probably would add delays in the fast_switch >> and also brings little value. >> For the normal channel, where we have spinlocks and other stuff, this >> atomic_inc() could stay in my opinion. >> >> Regards, >> Lukasz > Hi Lukasz, > > We currently do not use "fast channels" - although it is possible we might someday. > I find the transfer_id useful per your v2 even if it doesn't cover FC.  Thanks for > submitting and discussing this! Thank you for cooperation. Regards, Lukasz > > Regards, > Jim Quinlan >