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=-13.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 D5FEEC4338F for ; Wed, 25 Aug 2021 10:02:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B3D076127B for ; Wed, 25 Aug 2021 10:02:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239861AbhHYKDY (ORCPT ); Wed, 25 Aug 2021 06:03:24 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:24632 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239683AbhHYKDW (ORCPT ); Wed, 25 Aug 2021 06:03:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1629885756; 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: in-reply-to:in-reply-to:references:references; bh=TNQw5M7GXPNq6aXAA7yK5iUMHOIbWCguNiz70Y3FyJs=; b=RLDdZUex+GAcw4mPLW05fpJPhciEB5e7ZE2xmUaohhozKutn0AhQeAfDRwXcV6bb0bbAw7 BP2spp9vqCvatnbUYSDo5uyYAZ2/2g7UBa0EYgxj8a6wDUzzWpCSF6KfDrnjXhka8EA6K+ Sx6QvwjnZEwa0Tl5pEuloJDLyCv1WMk= 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-587-ErSM2KAfOY-vjF_cnFabgQ-1; Wed, 25 Aug 2021 06:02:35 -0400 X-MC-Unique: ErSM2KAfOY-vjF_cnFabgQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9EA0D180FCA7; Wed, 25 Aug 2021 10:02:33 +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 E5CE719C59; Wed, 25 Aug 2021 10:02:25 +0000 (UTC) Received: by fuller.cnet (Postfix, from userid 1000) id 3364F416D8BC; Wed, 25 Aug 2021 07:02:21 -0300 (-03) Date: Wed, 25 Aug 2021 07:02:21 -0300 From: Marcelo Tosatti To: linux-kernel@vger.kernel.org Cc: Nitesh Lal , Nicolas Saenz Julienne , Frederic Weisbecker , Christoph Lameter , Juri Lelli , Peter Zijlstra , Alex Belits , Peter Xu , Thomas Gleixner Subject: Re: [patch V3 0/8] extensible prctl task isolation interface and vmstat sync Message-ID: <20210825100221.GB83176@fuller.cnet> References: <20210824152423.300346181@fuller.cnet> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210824152423.300346181@fuller.cnet> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org +CC Thomas. On Tue, Aug 24, 2021 at 12:24:23PM -0300, Marcelo Tosatti wrote: > > The logic to disable vmstat worker thread, when entering > nohz full, does not cover all scenarios. For example, it is possible > for the following to happen: > > 1) enter nohz_full, which calls refresh_cpu_vm_stats, syncing the stats. > 2) app runs mlock, which increases counters for mlock'ed pages. > 3) start -RT loop > > Since refresh_cpu_vm_stats from nohz_full logic can happen _before_ > the mlock, vmstat shepherd can restart vmstat worker thread on > the CPU in question. > > To fix this, add task isolation prctl interface to quiesce > deferred actions when returning to userspace. > > The patchset is based on ideas and code from the > task isolation patchset from Alex Belits: > https://lwn.net/Articles/816298/ > > Please refer to Documentation/userspace-api/task_isolation.rst > (patch 2) for details. > > Note: the prctl interface is independent of nohz_full=. > > --------- > > v3: > > - Split in smaller patches (Nitesh Lal). > - Misc cleanups (Nitesh Lal). > - Clarify nohz_full is not a dependency (Nicolas Saenz). > - Incorrect values for prctl definitions (kernel robot). > - Save configured state, so applications > can activate externally configured > task isolation parameters. > - Remove "system default" notion (chisol should > make it obsolete). > - Update documentation: add new section with explanation > about configuration/activation and code example. > - Update samples. > - Report configuration/activation state at > /proc/pid/task_isolation. > - Condense dirty information of per-CPU vmstats counters > in a bool. > - In-kernel KVM support. > - Add support to configure inheritance on fork and exec. > > v2: > > - Finer-grained control of quiescing (Frederic Weisbecker / Nicolas Saenz). > > - Avoid potential regressions by allowing applications > to use ISOL_F_QUIESCE_DEFMASK (whose default value > is configurable in /sys/). (Nitesh Lal / Nicolas Saenz). > > v2 can be found at: > https://lore.kernel.org/patchwork/project/lkml/list/?series=510225 > > > --- > > Documentation/userspace-api/task_isolation.rst | 281 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > arch/x86/kvm/x86.c | 3 > fs/proc/base.c | 68 +++++++++++++++++++ > include/linux/sched.h | 5 + > include/linux/task_isolation.h | 131 ++++++++++++++++++++++++++++++++++++++ > include/linux/vmstat.h | 17 ++++ > include/uapi/linux/prctl.h | 27 +++++++ > init/init_task.c | 3 > kernel/Makefile | 2 > kernel/entry/common.c | 2 > kernel/exit.c | 2 > kernel/fork.c | 23 ++++++ > kernel/sys.c | 26 +++++++ > kernel/task_isolation.c | 315 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > mm/vmstat.c | 167 ++++++++++++++++++++++++++++++++++++------------ > samples/Kconfig | 7 ++ > samples/Makefile | 1 > samples/task_isolation/Makefile | 9 ++ > samples/task_isolation/task_isol.c | 83 ++++++++++++++++++++++++ > samples/task_isolation/task_isol.h | 9 ++ > samples/task_isolation/task_isol_userloop.c | 56 ++++++++++++++++ > 21 files changed, 1194 insertions(+), 43 deletions(-) > >