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=-7.6 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 22049C4363C for ; Wed, 7 Oct 2020 18:05:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B57DB21707 for ; Wed, 7 Oct 2020 18:05:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="YmZW/IcH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728414AbgJGSFK (ORCPT ); Wed, 7 Oct 2020 14:05:10 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:33855 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727085AbgJGSFK (ORCPT ); Wed, 7 Oct 2020 14:05:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602093909; 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=p5JHnvclYDLHKHB4GAf0Q2qFX9EM0QTp+UrXTsO6WlI=; b=YmZW/IcHTXONliJdaXVwX0027U716fYOEuR2g1AAKY34vIMmpeNdsG4byaE6mFaWCbpjgU ccXxBOTiWNu/UgYxzqstkv5kOqVezyQ3+jRKHb0v1NWORZavpUQ9hr4yEY3kEAoQlbA9XJ yGv9p0zI9qQx4MYiPszUVAcioOvUDYY= 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-195-OWTDjFJJNlG1aVzf61JSmQ-1; Wed, 07 Oct 2020 14:05:07 -0400 X-MC-Unique: OWTDjFJJNlG1aVzf61JSmQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E52C38027E1; Wed, 7 Oct 2020 18:05:02 +0000 (UTC) Received: from fuller.cnet (ovpn-112-4.gru2.redhat.com [10.97.112.4]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 41C595D9DD; Wed, 7 Oct 2020 18:04:57 +0000 (UTC) Received: by fuller.cnet (Postfix, from userid 1000) id 6A339417D683; Wed, 7 Oct 2020 15:04:33 -0300 (-03) Message-ID: <20201007180229.765691166@redhat.com> User-Agent: quilt/0.66 Date: Wed, 07 Oct 2020 15:01:53 -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: <20201007180151.623061463@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 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 @@ -398,7 +398,15 @@ EXPORT_SYMBOL_GPL(tick_nohz_dep_clear_ta */ void tick_nohz_dep_set_signal(struct signal_struct *sig, enum tick_dep_bits bit) { - tick_nohz_dep_set_all(&sig->tick_dep_mask, bit); + int prev; + + prev = atomic_fetch_or(BIT(bit), &sig->tick_dep_mask); + if (!prev) { + rcu_read_lock(); + for_each_thread(sig, t) + tick_nohz_kick_task(t); + rcu_read_unlock(); + } } void tick_nohz_dep_clear_signal(struct signal_struct *sig, enum tick_dep_bits bit)