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=-11.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 68D86C4167B for ; Mon, 7 Dec 2020 13:07:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2F84522838 for ; Mon, 7 Dec 2020 13:07:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726314AbgLGNHX (ORCPT ); Mon, 7 Dec 2020 08:07:23 -0500 Received: from mail.kernel.org ([198.145.29.99]:34018 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725867AbgLGNHW (ORCPT ); Mon, 7 Dec 2020 08:07:22 -0500 Date: Mon, 7 Dec 2020 14:06:39 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1607346402; bh=/S4wAAJphnrhh2Uzis7jKmvU2S4fC/taQwaYkyRT5MY=; h=From:To:Cc:Subject:References:In-Reply-To:From; b=XVJ+QEd/YpHRqtQbJ3Y6WBR14e3iG6y2rf3HNSM/zuGGEPdnoWq8v+HflJL1piOQO jzLABBTXfiteouQl8DLeiHfPdvf0lvciH/vjCZCYv2bOE+Vd8gi2HHy4jRUq5/oim6 SNyvBBtrn2Ar44gu9j9jeL3qPt/yhExcc0Gy+NdX++4bDqijLqQ0/lSO66iPOsS+Hj mfmhX0PKy80KafSaHsmgZ8efp0cLoj6JYCCiPAhD0JuJ85zU2fUNkw6zs5i1mHd2RS ZhpkbzIQyw6vq+EggbGqjMj2uNrkRZGmX7CPBvkDnHMLBHW1iTFjVcrR4CvARaKYNf YLHFvN0q5ZQfQ== From: Frederic Weisbecker To: Thomas Gleixner Cc: LKML , Peter Zijlstra , Paul McKenney , Sebastian Andrzej Siewior Subject: Re: [patch V2 1/9] softirq: Add RT specific softirq accounting Message-ID: <20201207130639.GB122233@lothringen> References: <20201204170151.960336698@linutronix.de> <20201204170804.765109984@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201204170804.765109984@linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 04, 2020 at 06:01:52PM +0100, Thomas Gleixner wrote: > From: Thomas Gleixner > > RT requires the softirq processing and local bottomhalf disabled regions to > be preemptible. Using the normal preempt count based serialization is > therefore not possible because this implicitely disables preemption. > > RT kernels use a per CPU local lock to serialize bottomhalfs. As > local_bh_disable() can nest the lock can only be acquired on the outermost > invocation of local_bh_disable() and released when the nest count becomes > zero. Tasks which hold the local lock can be preempted so its required to > keep track of the nest count per task. > > Add a RT only counter to task struct and adjust the relevant macros in > preempt.h. > > Signed-off-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker