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 616DBF3C982 for ; Tue, 24 Feb 2026 14:35:18 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vutVB-00070h-Og; Tue, 24 Feb 2026 09:35:05 -0500 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 1vutVA-000709-Re for qemu-devel@nongnu.org; Tue, 24 Feb 2026 09:35:04 -0500 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 1vutV8-0000Lp-QL for qemu-devel@nongnu.org; Tue, 24 Feb 2026 09:35:04 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1771943701; 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=M/s3DG4kRsNUk5cHSh4ez25A+ETDhRhwrwtAC4X8QkQ=; b=X3rXSXynm78CaC0rv7oTH6BMJ69mGVYl/gB2q6dUJ7Rs5oHY0lpwiVP25avcq7+W4sLPH1 PJJ9CiPnjqOJ4miUaCNxNRweJNccpVwSv6b4Ela3CzfxEip33WkLRXaS0ZnURF3UqVrsSk NbHCPOAc91l7y637bK+jWhh1R0gM3rM= Received: from mx-prod-mc-06.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-650-dX3TwfkmMTCYTarAAAjc9w-1; Tue, 24 Feb 2026 09:34:57 -0500 X-MC-Unique: dX3TwfkmMTCYTarAAAjc9w-1 X-Mimecast-MFC-AGG-ID: dX3TwfkmMTCYTarAAAjc9w_1771943697 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B57311800266; Tue, 24 Feb 2026 14:34:56 +0000 (UTC) Received: from redhat.com (unknown [10.45.225.66]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id CF450195419A; Tue, 24 Feb 2026 14:34:54 +0000 (UTC) Date: Tue, 24 Feb 2026 15:34:52 +0100 From: Kevin Wolf To: Fiona Ebner Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, hreitz@redhat.com, jsnow@redhat.com Subject: Re: [PATCH] hw/block/block: add 'throttle-group' property Message-ID: References: <20260116143946.1031006-1-f.ebner@proxmox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260116143946.1031006-1-f.ebner@proxmox.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -10 X-Spam_score: -1.1 X-Spam_bar: - X-Spam_report: (-1.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_RPBL_BLOCKED=0.358, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.659, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development 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 Am 16.01.2026 um 15:39 hat Fiona Ebner geschrieben: > With '-drive', it is possible to specify the throttle configuration > directly on the commandline. Add the possibility to do the same when > using the modern way with '-blockdev' and a front-end device. Using a > throttle filter block node is not always an option: in particular, the > mirror block job operates on a root block node and it might be desired > to throttle only the guest IO, but not to the block job. Hm, is there still a reason why we require a root node for the source? > There already is a 'block_set_io_throttle' QMP command, but it's nicer > to be able to do it via the commandline too. > > Signed-off-by: Fiona Ebner > --- > > Hope I didn't miss a way to do this already. > > Should changing via qom-set be supported? Currently, an attempt fails: > > Error: Attempt to set property 'throttle-group' on device 'scsi0' > > (type 'scsi-hd') after it was realized > but there already is the 'block_set_io_throttle' QMP command. It would be nice, but I don't think runtime writable properties are used much in devices because I believe this would have to be done with plain QOM properties, i.e. outside of qdev. Though if it's actually easy, we could consider implementing it. > hw/block/block.c | 15 +++++++++++++++ > include/hw/block/block.h | 4 +++- > tests/qemu-iotests/172.out | 38 ++++++++++++++++++++++++++++++++++++++ > 3 files changed, 56 insertions(+), 1 deletion(-) Looks good to me, though maybe we could also use a qemu-iotests case that actually tries to set the property instead of only updating the output everywhere for having no throttle group. Kevin