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=-7.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 C3F00C433E1 for ; Wed, 29 Jul 2020 14:53:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A0AEA22B43 for ; Wed, 29 Jul 2020 14:53:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596034406; bh=fp2UmJ60nahw5GDWRN0Aw65GthA1YO0B+AQzyViir4U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=Nguy2LPWTqSSYXHzPYrwKmR7piyjckbaAwZLQcjGGzc0PjLF6ozkQtUNh3mQpFoZM +fhMDaXVIwHQPtizv6ax1oI2ioth2yai0qjarQ+eYo5nKqpBoDtxTPcel+GcBDqrdn Sw+573TnoOT4M2Dz5H56XMJNJpaK0R63XetMH9Ug= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727008AbgG2OxV (ORCPT ); Wed, 29 Jul 2020 10:53:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:34370 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726909AbgG2OxT (ORCPT ); Wed, 29 Jul 2020 10:53:19 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6A29121744; Wed, 29 Jul 2020 14:53:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596034399; bh=fp2UmJ60nahw5GDWRN0Aw65GthA1YO0B+AQzyViir4U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UBUvVV1R89Ln+j78ufGotq8p+n7KvD1YVJ6LxenHh/ilGpPs6Yb/uV+v+mTZ424aG KnA2dbpF0QwLxV/NYoYPAjeU0uaOI0lbYVQB7MO43C4c0yEkbBuypsETuRVcG1PMsB 8y8MscqKKOtrXTt1lKOBxzm507dEdnSfuCz5d3hk= Date: Wed, 29 Jul 2020 16:53:09 +0200 From: Greg Kroah-Hartman To: Badhri Jagan Sridharan Cc: Guenter Roeck , Heikki Krogerus , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] usb: typec: tcpm: Migrate workqueue to RT priority for processing events Message-ID: <20200729145309.GA3490882@kroah.com> References: <20200724020551.2737376-1-badhri@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200724020551.2737376-1-badhri@google.com> Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Thu, Jul 23, 2020 at 07:05:51PM -0700, Badhri Jagan Sridharan wrote: > "tReceiverResponse 15 ms Section 6.6.2 > The receiver of a Message requiring a response Shall respond > within tReceiverResponse in order to ensure that the > sender’s SenderResponseTimer does not expire." > > When the cpu complex is busy running other lower priority > work items, TCPM's work queue sometimes does not get scheduled > on time to meet the above requirement from the spec. > Moving to kthread_work apis to run with real time priority. > Just lower than the default threaded irq priority, > MAX_USER_RT_PRIO/2 + 1. (Higher number implies lower priority). > > Further, as observed in 1ff688209e2e, moving to hrtimers to > overcome scheduling latency while scheduling the delayed work. > > TCPM has three work streams: > 1. tcpm_state_machine > 2. vdm_state_machine > 3. event_work > > tcpm_state_machine and vdm_state_machine both schedule work in > future i.e. delayed. Hence each of them have a corresponding > hrtimer, tcpm_state_machine_timer & vdm_state_machine_timer. > > When work is queued right away kthread_queue_work is used. > Else, the relevant timer is programmed and made to queue > the kthread_work upon timer expiry. > > kthread_create_worker only creates one kthread worker thread, > hence single threadedness of workqueue is retained. > > Signed-off-by: Badhri Jagan Sridharan This doesn't apply against my usb-next branch at all. Can you rebase and resend? Remember to collect the reviewed-by tags as well when you do so. thanks, greg k-h