From 228529d1fec305c05a7c7e173258b1c939ef3b1b Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Tue, 22 Oct 2024 15:45:01 -0400 Subject: [PATCH] migration: Deprecate query-migrationthreads command 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 Link: https://lore.kernel.org/r/20241022194501.1022443-1-peterx@redhat.com Signed-off-by: Peter Xu --- 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 1e1e9f5f18b..8e85607bddc 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 3af6aa17405..a605dc26dbc 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: -- 2.39.5