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=-6.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 D39FDC433E7 for ; Thu, 8 Oct 2020 19:18:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6AE2D221FE for ; Thu, 8 Oct 2020 19:18:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fivuwW5K" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728807AbgJHTSV (ORCPT ); Thu, 8 Oct 2020 15:18:21 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:48122 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725874AbgJHTSU (ORCPT ); Thu, 8 Oct 2020 15:18:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602184699; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=OcZS5FlPZvMeBO/kURU+SArFk5dBZ8JD4IGHErhHSyc=; b=fivuwW5KlYld+mEKPKEFV5bXiDAEmPLNKw+WvZ2jHgmbQNWAQ6WsFNmo7JiuJk2FGGXH1D a3YMpYxN6s1agiHGoaigYwcNOjZTEHWAMAwuA3CU+jIMo6ViOO6MD6fJ8d1luAejaQcIyu hjHiOIX7GX3YZniahk8hY+6jEVgL4zY= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-406-OvrW8t3zOE-Xm4NrISwybw-1; Thu, 08 Oct 2020 15:18:17 -0400 X-MC-Unique: OvrW8t3zOE-Xm4NrISwybw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 48C2A1084D70; Thu, 8 Oct 2020 19:18:16 +0000 (UTC) Received: from fuller.cnet (ovpn-112-7.gru2.redhat.com [10.97.112.7]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4439510013C1; Thu, 8 Oct 2020 19:18:09 +0000 (UTC) Received: by fuller.cnet (Postfix, from userid 1000) id 6DE6D4168BB6; Thu, 8 Oct 2020 16:17:42 -0300 (-03) Message-ID: <20201008191446.048306320@redhat.com> User-Agent: quilt/0.66 Date: Thu, 08 Oct 2020 16:11:31 -0300 From: Marcelo Tosatti To: linux-kernel@vger.kernel.org Cc: Frederic Weisbecker , Peter Zijlstra , Nitesh Narayan Lal , Peter Xu , Marcelo Tosatti Subject: [patch 2/2] nohz: change signal tick dependency to wakeup CPUs of member tasks References: <20201008191129.152030255@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Rather than waking up all nohz_full CPUs on the system, only wakeup the target CPUs of member threads of the signal. Reduces interruptions to nohz_full CPUs. Signed-off-by: Marcelo Tosatti Index: linux-2.6/kernel/time/tick-sched.c =================================================================== --- linux-2.6.orig/kernel/time/tick-sched.c +++ linux-2.6/kernel/time/tick-sched.c @@ -396,9 +396,17 @@ EXPORT_SYMBOL_GPL(tick_nohz_dep_clear_ta * Set a per-taskgroup tick dependency. Posix CPU timers need this in order to elapse * per process timers. */ -void tick_nohz_dep_set_signal(struct signal_struct *sig, enum tick_dep_bits bit) +void tick_nohz_dep_set_signal(struct task_struct *tsk, enum tick_dep_bits bit) { - tick_nohz_dep_set_all(&sig->tick_dep_mask, bit); + int prev; + struct task_struct *p; + + prev = atomic_fetch_or(BIT(bit), &tsk->signal->tick_dep_mask); + if (!prev) { + lockdep_assert_held(&tsk->sighand->siglock); + for_each_thread(tsk, p) + tick_nohz_kick_task(p); + } } void tick_nohz_dep_clear_signal(struct signal_struct *sig, enum tick_dep_bits bit) Index: linux-2.6/include/linux/tick.h =================================================================== --- linux-2.6.orig/include/linux/tick.h +++ linux-2.6/include/linux/tick.h @@ -207,7 +207,7 @@ extern void tick_nohz_dep_set_task(struc enum tick_dep_bits bit); extern void tick_nohz_dep_clear_task(struct task_struct *tsk, enum tick_dep_bits bit); -extern void tick_nohz_dep_set_signal(struct signal_struct *signal, +extern void tick_nohz_dep_set_signal(struct task_struct *tsk, enum tick_dep_bits bit); extern void tick_nohz_dep_clear_signal(struct signal_struct *signal, enum tick_dep_bits bit); @@ -252,11 +252,11 @@ static inline void tick_dep_clear_task(s if (tick_nohz_full_enabled()) tick_nohz_dep_clear_task(tsk, bit); } -static inline void tick_dep_set_signal(struct signal_struct *signal, +static inline void tick_dep_set_signal(struct task_struct *tsk, enum tick_dep_bits bit) { if (tick_nohz_full_enabled()) - tick_nohz_dep_set_signal(signal, bit); + tick_nohz_dep_set_signal(tsk, bit); } static inline void tick_dep_clear_signal(struct signal_struct *signal, enum tick_dep_bits bit) @@ -284,7 +284,7 @@ static inline void tick_dep_set_task(str enum tick_dep_bits bit) { } static inline void tick_dep_clear_task(struct task_struct *tsk, enum tick_dep_bits bit) { } -static inline void tick_dep_set_signal(struct signal_struct *signal, +static inline void tick_dep_set_signal(struct task_struct *tsk, enum tick_dep_bits bit) { } static inline void tick_dep_clear_signal(struct signal_struct *signal, enum tick_dep_bits bit) { } Index: linux-2.6/kernel/time/posix-cpu-timers.c =================================================================== --- linux-2.6.orig/kernel/time/posix-cpu-timers.c +++ linux-2.6/kernel/time/posix-cpu-timers.c @@ -523,7 +523,7 @@ static void arm_timer(struct k_itimer *t if (CPUCLOCK_PERTHREAD(timer->it_clock)) tick_dep_set_task(p, TICK_DEP_BIT_POSIX_TIMER); else - tick_dep_set_signal(p->signal, TICK_DEP_BIT_POSIX_TIMER); + tick_dep_set_signal(p, TICK_DEP_BIT_POSIX_TIMER); } /* @@ -1358,7 +1358,7 @@ void set_process_cpu_timer(struct task_s if (*newval < *nextevt) *nextevt = *newval; - tick_dep_set_signal(tsk->signal, TICK_DEP_BIT_POSIX_TIMER); + tick_dep_set_signal(tsk, TICK_DEP_BIT_POSIX_TIMER); } static int do_cpu_nanosleep(const clockid_t which_clock, int flags,