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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 5DB84C7618F for ; Fri, 26 Jul 2019 19:19:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 37FE4218B8 for ; Fri, 26 Jul 2019 19:19:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388625AbfGZTTE (ORCPT ); Fri, 26 Jul 2019 15:19:04 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:50208 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388586AbfGZTTB (ORCPT ); Fri, 26 Jul 2019 15:19:01 -0400 Received: from localhost ([127.0.0.1] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1hr5k2-0001BU-Uo; Fri, 26 Jul 2019 21:18:59 +0200 Message-Id: <20190726185753.551967692@linutronix.de> User-Agent: quilt/0.65 Date: Fri, 26 Jul 2019 20:30:57 +0200 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Steven Rostedt , Sebastian Siewior , Anna-Maria Gleixner , Arnaldo Carvalho de Melo , Jiri Olsa , Paolo Bonzini , Juergen Gross Subject: [patch 09/12] hrtimer: Move unmarked hrtimers to soft interrupt expiry on RT References: <20190726183048.982726647@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sebastian Andrzej Siewior On PREEMPT_RT not all hrtimers can be expired in hard interrupt context even if that is perfectly fine on a PREEMPT_RT=n kernel, e.g. because they take regular spinlocks. Also for latency reasons PREEMPT_RT tries to defer most hrtimers' expiry into softirq context. hrtimers marked with HRTIMER_MODE_HARD must be kept in hard interrupt context expiry mode. Add the required logic. No functional change for PREEMPT_RT=n kernels. [ tglx: Split out of a larger combo patch. Added changelog ] Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner --- kernel/time/hrtimer.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -1271,8 +1271,16 @@ static void __hrtimer_init(struct hrtime enum hrtimer_mode mode) { bool softtimer = !!(mode & HRTIMER_MODE_SOFT); - int base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0; struct hrtimer_cpu_base *cpu_base; + int base; + + /* + * On PREEMPT_RT enabled kernels hrtimers which are not explicitely + * marked for hard interrupt expiry mode are moved into soft + * interrupt context for latency reasons. + */ + if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(mode & HRTIMER_MODE_HARD)) + softtimer = true; memset(timer, 0, sizeof(struct hrtimer)); @@ -1286,6 +1294,7 @@ static void __hrtimer_init(struct hrtime if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL) clock_id = CLOCK_MONOTONIC; + base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0; base += hrtimer_clockid_to_base(clock_id); timer->is_soft = softtimer; timer->base = &cpu_base->clock_base[base];