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=-7.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_2 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 016EBC47087 for ; Fri, 28 May 2021 11:33:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D2E8461378 for ; Fri, 28 May 2021 11:33:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233429AbhE1Lf3 (ORCPT ); Fri, 28 May 2021 07:35:29 -0400 Received: from mail.kernel.org ([198.145.29.99]:44374 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230047AbhE1Lf1 (ORCPT ); Fri, 28 May 2021 07:35:27 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id BB148613D1; Fri, 28 May 2021 11:33:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622201633; bh=l0M6J04UfHv6uie7fIhhs5YaSMy3FkfUd96P/oCu1os=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=MxgWKy/5pA7866NOldsAEENFhB6XYYQPjkjJDE2BHTeejLHDsJCPAxRd0rGg3mtMQ GGhMzW/4c62C345pg9SU/DYAam9ieqHp4aS7W2iqleD8O64xrt+16EpRylQ5mlAEjk cJSdPMQBTnpLSDGbuDcWD1pteUx6eakvgl0BP1VnYQ4jcKXnogf+6DO1xFOu2Wmweb b4zZY0hGaVdmX4vKvvX4wElohGtEc26Y+jisqArRRutEAsVHdpHqrU1LygFbnhDRnA IIZ6qrL2xtlU5dylrU2YEGLtVmjsqmNRXOhK+7GJYqDPqejczcj4n9907/aFFE1dAx KAHxREGWzS7RQ== Date: Fri, 28 May 2021 13:33:47 +0200 From: Mauro Carvalho Chehab To: Pavel Machek Cc: Marek =?UTF-8?B?QmVow7pu?= , linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org, linuxarm@huawei.com, mauro.chehab@huawei.com, gregkh@linuxfoundation.org Subject: Re: [PATCH v2 16/17] leds: leds-nuc: add support for changing the ethernet type indicator Message-ID: <20210528133347.46634db7@coco.lan> In-Reply-To: <20210526145112.GB2141@amd> References: <20210519141102.0161a9d9@thinkpad> <20210519162413.4feeab02@coco.lan> <20210519175503.567e6ecc@thinkpad> <20210519203014.1838de3a@coco.lan> <20210520130014.7189a315@dellmb> <20210520180028.495f94e4@coco.lan> <20210520183633.084a8c3f@thinkpad> <20210520205933.3cfc57a9@coco.lan> <20210520220703.5a86b994@thinkpad> <20210521111400.127ffa10@coco.lan> <20210526145112.GB2141@amd> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Wed, 26 May 2021 16:51:12 +0200 Pavel Machek escreveu: > Hi! > > > > You say that for this controller it would be bad to do in SW, because it > > > would take too much time in BIOS calls. (I wonder how much...) > > > > Yeah, it would be interesting to know how much. However, measuring BIOS > > latency and time spent on such calls can be tricky: one needs to use a > > high-res clock that it is not used anywhere else, in order to measure > > it. > > I'm sure you can time kernel compilation while LEDs are using software > netdev trigger, for example. I can't see how. I mean, the problem is to monitor the impact of the BIOS call with may affect not only the application using the LED, but all other applications running at the same time on different CPUs, as the BIOS may want/need to lock other CPUs while its code is running, as it can't see the Linux CPU locks. Thanks, Mauro