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[99.254.114.190]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7b1659bb8besm314663185a.13.2024.10.22.12.45.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Oct 2024 12:45:03 -0700 (PDT) From: Peter Xu To: qemu-devel@nongnu.org Cc: Julia Suvorova , "Dr . David Alan Gilbert" , Prasad Pandit , peterx@redhat.com, Juraj Marcin , Fabiano Rosas , =?utf-8?q?Daniel_P_=2E_Berrang=C3=A9?= , Markus Armbruster Subject: [PATCH v2] migration: Deprecate query-migrationthreads command Date: Tue, 22 Oct 2024 15:45:01 -0400 Message-ID: <20241022194501.1022443-1-peterx@redhat.com> X-Mailer: git-send-email 2.45.0 MIME-Version: 1.0 Received-SPF: pass client-ip=170.10.129.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.519, 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_H2=-1.697, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_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 Per previous discussion [1,2], this patch deprecates query-migrationthreads command. To summarize, the major reason of the deprecation is due to no sensible way to consume the API properly: (1) The reported list of threads are incomplete (ignoring destination threads and non-multifd threads). (2) For CPU pinning, there's no way to properly pin the threads with the API if the threads will start running right away after migration threads can be queried, so the threads will always run on the default cores for a short window. (3) For VM debugging, one can use "-name $VM,debug-threads=on" instead, which will provide proper names for all migration threads. [1] https://lore.kernel.org/r/20240930195837.825728-1-peterx@redhat.com [2] https://lore.kernel.org/r/20241011153417.516715-1-peterx@redhat.com Reviewed-by: Fabiano Rosas Acked-by: Markus Armbruster Signed-off-by: Peter Xu --- v2: - truncate long '-' line [Dan] - Remove warn_report() [Markus] - Proper spacing in qapi/ after "Features:" [Markus] --- docs/about/deprecated.rst | 8 ++++++++ qapi/migration.json | 7 ++++++- 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst index ce38a3d0cf..100ba66fe1 100644 --- a/docs/about/deprecated.rst +++ b/docs/about/deprecated.rst @@ -147,6 +147,14 @@ options are removed in favor of using explicit ``blockdev-create`` and ``blockdev-add`` calls. See :doc:`/interop/live-block-operations` for details. +``query-migrationthreads`` (since 9.2) +'''''''''''''''''''''''''''''''''''''' + +To be removed with no replacement, as it reports only a limited set of +threads (for example, it only reports source side of multifd threads, +without reporting any destination threads, or non-multifd source threads). +For debugging purpose, please use ``-name $VM,debug-threads=on`` instead. + Incorrectly typed ``device_add`` arguments (since 6.2) '''''''''''''''''''''''''''''''''''''''''''''''''''''' diff --git a/qapi/migration.json b/qapi/migration.json index 3af6aa1740..a605dc26db 100644 --- a/qapi/migration.json +++ b/qapi/migration.json @@ -2284,12 +2284,17 @@ # # Returns information of migration threads # +# Features: +# +# @deprecated: This command is deprecated with no replacement yet. +# # Returns: @MigrationThreadInfo # # Since: 7.2 ## { 'command': 'query-migrationthreads', - 'returns': ['MigrationThreadInfo'] } + 'returns': ['MigrationThreadInfo'], + 'features': ['deprecated'] } ## # @snapshot-save: