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 0C954C369CB for ; Tue, 29 Apr 2025 06:02:55 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1u9e3N-0007sh-I9; Tue, 29 Apr 2025 02:02:49 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1u9e3H-0007rR-4g for qemu-devel@nongnu.org; Tue, 29 Apr 2025 02:02:43 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1u9e3F-0004JT-Br for qemu-devel@nongnu.org; Tue, 29 Apr 2025 02:02:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1745906559; 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=maKZnjj9tQQkDQ50CARh8MuV67A8e13wgSWLydJW+1w=; b=gcL4Ikfp2BOf05IVIb3T7w8p1DSiTSu4vB5LhsQeqkZEHfPpCmjWt65HcAycWIkJ3WsUqw Ucj9mS/hJufQNnhUdkGFqMAycVBYUHzJ0mxXwWPILNZtr7M76C0h5VIOSJAyNLkr1eY6fE 5fDJdmEwPDEt49rESLn9aO2Aqux4eQk= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-272-Kty8IKZXPNiEjOmoi07Nag-1; Tue, 29 Apr 2025 02:02:34 -0400 X-MC-Unique: Kty8IKZXPNiEjOmoi07Nag-1 X-Mimecast-MFC-AGG-ID: Kty8IKZXPNiEjOmoi07Nag_1745906553 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7D9121801A1A; Tue, 29 Apr 2025 06:02:33 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.27]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id ECB3519560AB; Tue, 29 Apr 2025 06:02:32 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 9EFB521E66C2; Tue, 29 Apr 2025 08:02:30 +0200 (CEST) From: Markus Armbruster To: Steven Sistare Cc: qemu-devel@nongnu.org, John Snow , Cleber Rosa , Eric Blake , Paolo Bonzini , "Daniel P. Berrange" , Eduardo Habkost , Fabiano Rosas , Laurent Vivier , devel@lists.libvirt.org Subject: Re: [PATCH V1 0/6] fast qom tree get In-Reply-To: <3c5e9e8d-a3c5-4179-800f-2c11d38b7b02@oracle.com> (Steven Sistare's message of "Mon, 28 Apr 2025 12:18:45 -0400") References: <1741036202-265696-1-git-send-email-steven.sistare@oracle.com> <87friheqcp.fsf@pond.sub.org> <86bb6d0f-63a1-4643-b58a-1186a73e3b17@oracle.com> <87selszp8o.fsf@pond.sub.org> <3c5e9e8d-a3c5-4179-800f-2c11d38b7b02@oracle.com> Date: Tue, 29 Apr 2025 08:02:30 +0200 Message-ID: <87v7qnpksp.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.484, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Steven Sistare writes: > On 4/28/2025 4:04 AM, Markus Armbruster wrote: >> Steven Sistare writes: >> >>> On 4/9/2025 3:39 AM, Markus Armbruster wrote: >>>> Hi Steve, I apologize for the slow response. >>>> >>>> Steve Sistare writes: >>>> >>>>> Using qom-list and qom-get to get all the nodes and property values in a >>>>> QOM tree can take multiple seconds because it requires 1000's of individual >>>>> QOM requests. Some managers fetch the entire tree or a large subset >>>>> of it when starting a new VM, and this cost is a substantial fraction of >>>>> start up time. >>>> >>>> "Some managers"... could you name one? >>> >>> My personal experience is with Oracle's OCI, but likely others could benefit. >> >> Elsewhere in this thread, we examined libvirt's use qom-get. Its use of >> qom-get is also noticably slow, and your work could speed it up. >> However, most of its use is for working around QMP interface >> shortcomings around probing CPU flags. Addressing these would help it >> even more. >> >> This makes me wonder what questions Oracle's OCI answers with the help >> of qom-get. Can you briefly describe them? >> >> Even if OCI would likewise be helped more by better QMP queries, your >> fast qom tree get work might still be useful. > > We already optimized our queries as a first step, but what remains is still > significant, which is why I submitted this RFE. I understand your motivation. I'd like to learn more on what OCI actually needs from QMP, to be able to better serve it and potentially other management applications.