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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 0CFD7C433EF for ; Fri, 15 Jun 2018 17:34:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BA196208B8 for ; Fri, 15 Jun 2018 17:34:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BA196208B8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966099AbeFORec (ORCPT ); Fri, 15 Jun 2018 13:34:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:48424 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965916AbeFOReb (ORCPT ); Fri, 15 Jun 2018 13:34:31 -0400 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (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 25EC820896; Fri, 15 Jun 2018 17:34:30 +0000 (UTC) Date: Fri, 15 Jun 2018 13:34:28 -0400 From: Steven Rostedt To: Thomas Gleixner Cc: Alan Stern , Mikulas Patocka , Ming Lei , Greg Kroah-Hartman , USB list , Kernel development list , Sebastian Sewior Subject: Re: High-priority softirqs [was: [PATCH] usb: don't offload isochronous urb completions to ksoftirq] Message-ID: <20180615133428.20205bae@gandalf.local.home> In-Reply-To: References: X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 15 Jun 2018 19:28:34 +0200 (CEST) Thomas Gleixner wrote: > One solution to that is to avoid both tasklets and kworkers and change the > USB code to make use of threaded interrupt handlers. I.e. handle the fast > stuff in the primary (hardirq) handler and delegate the rest to the irq > thread. That thread still can offload disk type stuff to a kworker if > needed. But the irq thread allows to bring the stuff under scheduler > control and experiments which I did a few years ago worked out pretty good. If there's any question about this, drivers can request to have their interrupt handlers run as threads. This has been added to mainline years ago. And it really should be the default solution before pushing off to tasklets or kworkers. -- Steve