From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A5DC3606A31B for ; Mon, 26 Oct 2026 06:41:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=fGetx2fE Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1xLENw-0008QE-0a; Mon, 26 Oct 2026 02:40:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xLENh-0008Gm-Hj for qemu-devel@nongnu.org; Mon, 26 Oct 2026 02:40:31 -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 1xLENd-0006Ws-KW for qemu-devel@nongnu.org; Mon, 26 Oct 2026 02:40:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1792996823; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vRIexE8VLxz98e3hq8yzh3iz97cTQ18xLnnLBdc6gFY=; b=fGetx2fE41mqQ5xAm7QC0U9gK5S0uzoCkJ5ryTDFwzEcP7cdpzOF5nGzP0rU4+cZoKfheD S0x+QoueNyxrztDJfyz2ZB8ug8oh1T7mX6egv0KdACntBsBvQu7zs0CrAN21PkbcgXDYfk G3YEA0JrOs+LmHt3exWXeJxQd8jf4bI= 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-94-qjQUAzCFPNKn-DxhULrJOg-1; Mon, 26 Oct 2026 02:40:15 -0400 X-MC-Unique: qjQUAzCFPNKn-DxhULrJOg-1 X-Mimecast-MFC-AGG-ID: qjQUAzCFPNKn-DxhULrJOg_1792996814 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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 4AD2D1800471; Mon, 26 Oct 2026 06:40:14 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.44.22.2]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E15C01800446; Mon, 26 Oct 2026 06:40:13 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 670EA21E6A04; Mon, 26 Oct 2026 07:40:11 +0100 (CET) From: Markus Armbruster To: Hanna Czenczek Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org, Kevin Wolf , John Snow , "Denis V . Lunev" , Eric Blake , Stefan Hajnoczi , Paolo Bonzini Subject: Re: [PATCH v2 07/12] qapi/block: Add BLOCK_IO_DONE event In-Reply-To: (Hanna Czenczek's message of "Fri, 23 Oct 2026 16:38:08 +0200") References: <20261019182028.45305-1-hreitz@redhat.com> <20261019182028.45305-8-hreitz@redhat.com> <871p9ksvx5.fsf@pond.sub.org> <87ld7pgcsy.fsf@pond.sub.org> Date: Mon, 26 Oct 2026 07:40:11 +0100 Message-ID: <87ecdd6k38.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 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: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.339, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-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: qemu development List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org X-Spam-Status: No, score=-17.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Hanna Czenczek writes: > On 23.10.26 08:18, Markus Armbruster wrote: >> Hanna Czenczek writes: >> >>> On 20.10.26 08:55, Markus Armbruster wrote: >>>> Hanna Czenczek writes: >>>> >>>>> This event is emitted when an operation completes, for which a >>>>> BLOCK_IO_DELAY event has previously been emitted. >>>>> >>>>> Signed-off-by: Hanna Czenczek >>>>> --- >>>>> qapi/block.json | 33 +++++++++++++++++++++++++++++++++ >>>>> 1 file changed, 33 insertions(+) >>>>> >>>>> diff --git a/qapi/block.json b/qapi/block.json >>>>> index 5f9f5c28050..38f293dd32d 100644 >>>>> --- a/qapi/block.json >>>>> +++ b/qapi/block.json [...] >>>>> @@ -686,3 +689,33 @@ >>>>> 'action': 'BlockErrorAction', >>>>> '*offset': 'uint64', >>>>> 'bytes': 'uint64' } } >>>>> + >>>>> +## >>>>> +# @BLOCK_IO_DONE: >>>>> +# >>>>> +# Emitted on completion for disk operations that previously emitted a >>>>> +# `BLOCK_IO_DELAY` event. >>>> >>>> Can we have multiple operations in flight that previously emitted >>>> BLOCK_IO_DELAY? >>>> >>>> If yes, might a management application need to connect the BLOCK_IO_DO= NE >>>> back to the BLOCK_IO_DELAY? >>>> >>>> If yes, how could it do that? >>> >>> Well, the combination of device, operation, offset, bytes. >>> >>> Do you think there should be an ID like a u64 counter per >>> BlockBackend? >> >> I'm not overly particular on how exactly the connection can be made. If >> the quadruple you suggested always suffices, that's good enough for me. >> Documentation should point it out, though. >> >> Can multiple operations with the same (device, operation, offset, bytes) >> be in flight? > > Technically, sure. > > Adding an ID is quite ugly, I feel like, which is why I would need your i= nput in how it would be least intrusive in QAPI. First step is to get a clearer idea on what exactly management applications need here. > (Caveat, at this point: I=E2=80=99m afraid I=E2=80=99ll be quite far from= my notebook for around four weeks=E2=80=A6 Thank you for your help so far = :)) No problem! [...] >>>>> +# >>>>> +# @qom-path: path to the block device object in the QOM tree >>>>> +# >>>>> +# @operation: I/O operation >>>>> +# >>>>> +# @latency-ns: Full duration of the operation (in nanoseconds) >>>>> +# >>>>> +# @offset: Request offset in the guest disk (in bytes), if available >>>> >>>> Out of curiosity: when could @offset be unavailable? >>> >>> For flushes. >> >> Uh, what's @bytes then? > > 0. I found that natural. Any offset value is a valid offset, but a value = of 0 for bytes sounded good to me. > > I now anticipate discomfort with this, so I can make @bytes optional, too= , yes. How much a flush writes and where is not known here. We can use 0 for "unknown" as long as we document it. "Absent" feels like the more obvious choice to me, though. Advice, not a demand. Same logic arguagbly applies to @offset, too. Regardless, the special case "flush" needs to be documented. [...]