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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D5880C433EF for ; Wed, 11 May 2022 09:47:16 +0000 (UTC) Received: from localhost ([::1]:53430 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1noiw7-0006k1-U3 for qemu-devel@archiver.kernel.org; Wed, 11 May 2022 05:47:15 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44550) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1noikP-00042Q-GZ for qemu-devel@nongnu.org; Wed, 11 May 2022 05:35:09 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:49225) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1noikM-0001Vt-8i for qemu-devel@nongnu.org; Wed, 11 May 2022 05:35:07 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1652261705; h=from:from:reply-to: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=TCUyWeoTAdznvjJTRmaU+kldP66AnHRMBIyYQ2kdEFM=; b=DXMhLnlo4GmZpROH/rgzsHO2Q5hhRDeVPRZocQbzEBRcfLGHQ/x8d2xis1MunA66qvoIrb a3vg/7EUbKyLPpps595Hivt5FD89v+tjNVXxvlMRfOpVmGay2H0uJyU4a7+kWW2s9uz8qj 9Iqnh9rp5ZCTqDyl1oWma4sdMDiacN4= 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-643-6NCafCZJMAy1gQOh2ZjFlQ-1; Wed, 11 May 2022 05:35:04 -0400 X-MC-Unique: 6NCafCZJMAy1gQOh2ZjFlQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 00D4F185A794 for ; Wed, 11 May 2022 09:35:04 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.142]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 58D817AF0; Wed, 11 May 2022 09:34:51 +0000 (UTC) Date: Wed, 11 May 2022 10:34:48 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: David Hildenbrand Cc: Michal Privoznik , qemu-devel@nongnu.org Subject: Re: [PATCH] util: NUMA aware memory preallocation Message-ID: References: <8a6b84ed-50bc-8f6e-4b71-7e15247c4ac0@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <8a6b84ed-50bc-8f6e-4b71-7e15247c4ac0@redhat.com> User-Agent: Mutt/2.1.5 (2021-12-30) X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, May 11, 2022 at 11:31:23AM +0200, David Hildenbrand wrote: > >> Long story short, management application has no way of learning > >> TIDs of allocator threads so it can't make them run NUMA aware. > > > > This feels like the key issue. The preallocation threads are > > invisible to libvirt, regardless of whether we're doing coldplug > > or hotplug of memory-backends. Indeed the threads are invisible > > to all of QEMU, except the memory backend code. > > > > Conceptually we need 1 or more explicit worker threads, that we > > can assign CPU affinity to, and then QEMU can place jobs on them. > > I/O threads serve this role, but limited to blockdev work. We > > need a generalization of I/O threads, for arbitrary jobs that > > QEMU might want to farm out to specific numa nodes. > > At least the "-object iothread" thingy can already be used for actions > outside of blockdev. virtio-balloon uses one for free page hinting. Ah that's good to know, so my idea probably isn't so much work as I thought it might be. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|