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=-3.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 ABEC3C433DF for ; Thu, 8 Oct 2020 19:18:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 494EB221FE for ; Thu, 8 Oct 2020 19:18:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="g/om7oVF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728630AbgJHTSV (ORCPT ); Thu, 8 Oct 2020 15:18:21 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:28427 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726864AbgJHTSU (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; bh=WAjg58k6zysC55xXuQSmmv3IfCLTn65IVmudRZhOFxQ=; b=g/om7oVF1qQTVXzMD1hGBhMqjI1btWC5NI0Ii7Vu+teLVxBQLzTMhBqq010lz6SM4acXCc GeQpGYGYl0ANAyLsZ5hod+e16DEZw1Fhv2ffD1RjnOSM34ZBWSnenFG1dHNdMiYziHRx84 p7fHVbnTlJrumQO39tZJi9XkwW/69wc= 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-450-sdhn-Y5_OnK1Vmbeb-y1Xw-1; Thu, 08 Oct 2020 15:18:17 -0400 X-MC-Unique: sdhn-Y5_OnK1Vmbeb-y1Xw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9C2E118BE16D; 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 3B7A9614F5; Thu, 8 Oct 2020 19:18:09 +0000 (UTC) Received: by fuller.cnet (Postfix, from userid 1000) id 673DF4168BA3; Thu, 8 Oct 2020 16:17:42 -0300 (-03) Message-ID: <20201008191129.152030255@redhat.com> User-Agent: quilt/0.66 Date: Thu, 08 Oct 2020 16:11:29 -0300 From: Marcelo Tosatti To: linux-kernel@vger.kernel.org Cc: Frederic Weisbecker , Peter Zijlstra , Nitesh Narayan Lal , Peter Xu Subject: [patch 0/2] nohz_full: only wakeup target CPUs when notifying new tick dependency (v3) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When enabling per-CPU posix timers, an IPI to nohz_full CPUs might be performed (to re-read the dependencies and possibly not re-enter nohz_full on a given CPU). A common case is for applications that run on nohz_full= CPUs to not use POSIX timers (eg DPDK). This patch changes the notification to only IPI the target CPUs where the task(s) whose tick dependencies are being updated are executing. This reduces interruptions to nohz_full= CPUs. --- v3: replace superfluous rcu_read_lock with lockdep_assert (PeterZ)