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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EB279C77B73 for ; Mon, 5 Jun 2023 19:15:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232963AbjFETPe (ORCPT ); Mon, 5 Jun 2023 15:15:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39402 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229792AbjFETP3 (ORCPT ); Mon, 5 Jun 2023 15:15:29 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A97FF120 for ; Mon, 5 Jun 2023 12:14:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1685992480; 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=SfydRo3YLfaDwYR7ylzaAXxWorOycnW9DfmBoaznkn8=; b=eeZz3mf8qH3j7Ur4VTjhB2/7bbzSeHro7DnLe16EhrCZtq2rnnmVa3Naj+M9Z3JdhphMyg KGqHkmeryoxTPjwPS5X/KzRPIGHHZ8enOdRcPQiT+IAuO8FsLxpaCARlri/7v/b4d8JHZG Ske6oMUx83SFnJlru38iynW2Sg12bv4= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-553-bc_Knc7RNfO_8NWo23UGlQ-1; Mon, 05 Jun 2023 15:14:37 -0400 X-MC-Unique: bc_Knc7RNfO_8NWo23UGlQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 305AF8032EF; Mon, 5 Jun 2023 19:14:37 +0000 (UTC) Received: from tpad.localdomain (ovpn-112-3.gru2.redhat.com [10.97.112.3]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F12F140CFD46; Mon, 5 Jun 2023 19:14:36 +0000 (UTC) Received: by tpad.localdomain (Postfix, from userid 1000) id 556E0400DC4D5; Mon, 5 Jun 2023 16:14:18 -0300 (-03) Date: Mon, 5 Jun 2023 16:14:18 -0300 From: Marcelo Tosatti To: Michal Hocko Cc: Christoph Lameter , Aaron Tomlin , Frederic Weisbecker , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Vlastimil Babka Subject: Re: [PATCH v2 2/3] vmstat: skip periodic vmstat update for nohz full CPUs Message-ID: References: <20230602185757.110910188@redhat.com> <20230602190115.521067386@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 05, 2023 at 08:57:15PM +0200, Michal Hocko wrote: > > Guest initiated I/O, since the host CPU is isolated. > > Make it explicit in the changelog. I think better use of our time would be to focus on https://lkml.iu.edu/hypermail/linux/kernel/2209.1/01263.html 1) Operate in terms of add CPU, remove CPU on sysfs (to avoid races). 2) Don't allow all CPUs to be marked as "block_interf". 3) Remove percpu rwsem lock. > I am just wondering how you can achieve your strict deadlines when IO is > involved but that is another story I guess. IO can be submitted when the ELF binary and libraries are read from the virtual disk, for example.