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Mon, 3 Jun 2024 11:17:55 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.93]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DFEA0202696B; Mon, 3 Jun 2024 11:17:54 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 1696221E681D; Mon, 3 Jun 2024 13:17:54 +0200 (CEST) From: Markus Armbruster To: Fiona Ebner Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, armbru@redhat.com, eblake@redhat.com, hreitz@redhat.com, kwolf@redhat.com, vsementsov@yandex-team.ru, jsnow@redhat.com Subject: Re: [PATCH v2 2/2] backup: add minimum cluster size to performance options In-Reply-To: <20240528120114.344416-3-f.ebner@proxmox.com> (Fiona Ebner's message of "Tue, 28 May 2024 14:01:14 +0200") References: <20240528120114.344416-1-f.ebner@proxmox.com> <20240528120114.344416-3-f.ebner@proxmox.com> Date: Mon, 03 Jun 2024 13:17:54 +0200 Message-ID: <87cyoytgv1.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.4 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable 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 Fiona Ebner writes: > In the context of backup fleecing, discarding the source will not work > when the fleecing image has a larger granularity than the one used for > block-copy operations (can happen if the backup target has smaller > cluster size), because cbw_co_pdiscard_snapshot() will align down the > discard requests and thus effectively ignore then. > > To make @discard-source work in such a scenario, allow specifying the > minimum cluster size used for block-copy operations and thus in > particular also the granularity for discard requests to the source. > > Suggested-by: Vladimir Sementsov-Ogievskiy > Signed-off-by: Fiona Ebner [...] > diff --git a/qapi/block-core.json b/qapi/block-core.json > index 8fc0a4b234..f1219a9dfb 100644 > --- a/qapi/block-core.json > +++ b/qapi/block-core.json > @@ -1551,11 +1551,16 @@ > # it should not be less than job cluster size which is calculated > # as maximum of target image cluster size and 64k. Default 0. > # > +# @min-cluster-size: Minimum size of blocks used by copy-before-write > +# and background copy operations. Has to be a power of 2. No > +# effect if smaller than the maximum of the target's cluster size > +# and 64 KiB. Default 0. (Since 9.1) > +# > # Since: 6.0 > ## > { 'struct': 'BackupPerf', > - 'data': { '*use-copy-range': 'bool', > - '*max-workers': 'int', '*max-chunk': 'int64' } } > + 'data': { '*use-copy-range': 'bool', '*max-workers': 'int', > + '*max-chunk': 'int64', '*min-cluster-size': 'size' } } > > ## > # @BackupCommon: QAPI schema Acked-by: Markus Armbruster