* Peter Xu (pet...@redhat.com) wrote: > This reverts two commits: > > 671326201dac8fe91222ba0045709f04a8ec3af4 > 1b1f4ab69c41279a45ccd0d3178e83471e6e4ec1 > > Meanwhile it adds an entry to removed-features.rst for the > query-migrationthreads QMP command. > > This patch originates from another patchset [1] that wanted to cleanup the > interface and add corresponding HMP command, as lots of things are missing > in the query report; so far it only reports the main thread and multifd > sender threads; all the rest migration threads are not reported, including > multifd recv threads. > > As pointed out by Dan in the follow up discussions [1], the API is designed > in an awkward way where CPU pinning may not cover the whole lifecycle of > even the thread being reported. When asked, we also didn't get chance to > hear from the developer who introduced this feature to explain how this API > can be properly used.
One suggestion for replacing it, might be a way for a management interface to add threads to a thread-pool, prior to migration; and then have migration use threads from that pool rather than creating it's own. Dave > OTOH, this feature from debugging POV isn't very helpful either, as all > these information can be easily obtained by GDB. Esepcially, if with > "-name $VM,debug-threads=on" we do already have names for each migration > threads (which covers more than multifd sender threads). > > So it looks like the API isn't helpful in any form as of now, besides it > only adds maintenance burden to migration code, even if not much. > > Considering that so far there's totally no justification on how to use this > interface correctly, let's remove this interface instead of cleaning it up. > > In this special case, we even go beyond normal deprecation procedure, > because a deprecation process would only make sense when there are existing > users. In this specific case, we expect zero serious users with this API. > > [1] > https://lore.kernel.org/qemu-devel/20240930195837.825728-1-pet...@redhat.com/ > > Cc: Jiang Jiacheng <jiangjiach...@huawei.com> > Signed-off-by: Peter Xu <pet...@redhat.com> > --- > docs/about/removed-features.rst | 6 ++++ > qapi/migration.json | 27 -------------- > migration/threadinfo.h | 25 ------------- > migration/migration.c | 6 ---- > migration/multifd.c | 5 --- > migration/threadinfo.c | 64 --------------------------------- > migration/meson.build | 1 - > 7 files changed, 6 insertions(+), 128 deletions(-) > delete mode 100644 migration/threadinfo.h > delete mode 100644 migration/threadinfo.c > > diff --git a/docs/about/removed-features.rst b/docs/about/removed-features.rst > index c76b91a88d..02ca43dec7 100644 > --- a/docs/about/removed-features.rst > +++ b/docs/about/removed-features.rst > @@ -693,6 +693,12 @@ Use ``multifd-channels`` instead. > > Use ``multifd-compression`` instead. > > +``query-migrationthreads`` (removed in 9.2) > +''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' > + > +Removed with no replacement. For debugging purpose, please use ``-name > +$VM,debug-threads=on`` instead. > + > QEMU Machine Protocol (QMP) events > ---------------------------------- > > diff --git a/qapi/migration.json b/qapi/migration.json > index 3af6aa1740..5520a51553 100644 > --- a/qapi/migration.json > +++ b/qapi/migration.json > @@ -2264,33 +2264,6 @@ > { 'command': 'query-vcpu-dirty-limit', > 'returns': [ 'DirtyLimitInfo' ] } > > -## > -# @MigrationThreadInfo: > -# > -# Information about migrationthreads > -# > -# @name: the name of migration thread > -# > -# @thread-id: ID of the underlying host thread > -# > -# Since: 7.2 > -## > -{ 'struct': 'MigrationThreadInfo', > - 'data': {'name': 'str', > - 'thread-id': 'int'} } > - > -## > -# @query-migrationthreads: > -# > -# Returns information of migration threads > -# > -# Returns: @MigrationThreadInfo > -# > -# Since: 7.2 > -## > -{ 'command': 'query-migrationthreads', > - 'returns': ['MigrationThreadInfo'] } > - > ## > # @snapshot-save: > # > diff --git a/migration/threadinfo.h b/migration/threadinfo.h > deleted file mode 100644 > index 2f356ff312..0000000000 > --- a/migration/threadinfo.h > +++ /dev/null > @@ -1,25 +0,0 @@ > -/* > - * Migration Threads info > - * > - * Copyright (c) 2022 HUAWEI TECHNOLOGIES CO., LTD. > - * > - * Authors: > - * Jiang Jiacheng <jiangjiach...@huawei.com> > - * > - * This work is licensed under the terms of the GNU GPL, version 2 or later. > - * See the COPYING file in the top-level directory. > - */ > - > -#include "qapi/error.h" > -#include "qapi/qapi-commands-migration.h" > - > -typedef struct MigrationThread MigrationThread; > - > -struct MigrationThread { > - const char *name; /* the name of migration thread */ > - int thread_id; /* ID of the underlying host thread */ > - QLIST_ENTRY(MigrationThread) node; > -}; > - > -MigrationThread *migration_threads_add(const char *name, int thread_id); > -void migration_threads_remove(MigrationThread *info); > diff --git a/migration/migration.c b/migration/migration.c > index 7609e0feed..12388c451d 100644 > --- a/migration/migration.c > +++ b/migration/migration.c > @@ -57,7 +57,6 @@ > #include "net/announce.h" > #include "qemu/queue.h" > #include "multifd.h" > -#include "threadinfo.h" > #include "qemu/yank.h" > #include "sysemu/cpus.h" > #include "yank_functions.h" > @@ -3466,16 +3465,12 @@ static void qemu_savevm_wait_unplug(MigrationState > *s, int old_state, > static void *migration_thread(void *opaque) > { > MigrationState *s = opaque; > - MigrationThread *thread = NULL; > int64_t setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST); > MigThrError thr_error; > bool urgent = false; > Error *local_err = NULL; > int ret; > > - thread = migration_threads_add(MIGRATION_THREAD_SRC_MAIN, > - qemu_get_thread_id()); > - > rcu_register_thread(); > > object_ref(OBJECT(s)); > @@ -3573,7 +3568,6 @@ out: > migration_iteration_finish(s); > object_unref(OBJECT(s)); > rcu_unregister_thread(); > - migration_threads_remove(thread); > return NULL; > } > > diff --git a/migration/multifd.c b/migration/multifd.c > index 697fe86fdf..659022e817 100644 > --- a/migration/multifd.c > +++ b/migration/multifd.c > @@ -26,7 +26,6 @@ > #include "qemu-file.h" > #include "trace.h" > #include "multifd.h" > -#include "threadinfo.h" > #include "options.h" > #include "qemu/yank.h" > #include "io/channel-file.h" > @@ -570,13 +569,10 @@ int multifd_send_sync_main(void) > static void *multifd_send_thread(void *opaque) > { > MultiFDSendParams *p = opaque; > - MigrationThread *thread = NULL; > Error *local_err = NULL; > int ret = 0; > bool use_packets = multifd_use_packets(); > > - thread = migration_threads_add(p->name, qemu_get_thread_id()); > - > trace_multifd_send_thread_start(p->id); > rcu_register_thread(); > > @@ -669,7 +665,6 @@ out: > } > > rcu_unregister_thread(); > - migration_threads_remove(thread); > trace_multifd_send_thread_end(p->id, p->packets_sent); > > return NULL; > diff --git a/migration/threadinfo.c b/migration/threadinfo.c > deleted file mode 100644 > index 262990dd75..0000000000 > --- a/migration/threadinfo.c > +++ /dev/null > @@ -1,64 +0,0 @@ > -/* > - * Migration Threads info > - * > - * Copyright (c) 2022 HUAWEI TECHNOLOGIES CO., LTD. > - * > - * Authors: > - * Jiang Jiacheng <jiangjiach...@huawei.com> > - * > - * This work is licensed under the terms of the GNU GPL, version 2 or later. > - * See the COPYING file in the top-level directory. > - */ > - > -#include "qemu/osdep.h" > -#include "qemu/queue.h" > -#include "qemu/lockable.h" > -#include "threadinfo.h" > - > -QemuMutex migration_threads_lock; > -static QLIST_HEAD(, MigrationThread) migration_threads; > - > -static void __attribute__((constructor)) migration_threads_init(void) > -{ > - qemu_mutex_init(&migration_threads_lock); > -} > - > -MigrationThread *migration_threads_add(const char *name, int thread_id) > -{ > - MigrationThread *thread = g_new0(MigrationThread, 1); > - thread->name = name; > - thread->thread_id = thread_id; > - > - WITH_QEMU_LOCK_GUARD(&migration_threads_lock) { > - QLIST_INSERT_HEAD(&migration_threads, thread, node); > - } > - > - return thread; > -} > - > -void migration_threads_remove(MigrationThread *thread) > -{ > - QEMU_LOCK_GUARD(&migration_threads_lock); > - if (thread) { > - QLIST_REMOVE(thread, node); > - g_free(thread); > - } > -} > - > -MigrationThreadInfoList *qmp_query_migrationthreads(Error **errp) > -{ > - MigrationThreadInfoList *head = NULL; > - MigrationThreadInfoList **tail = &head; > - MigrationThread *thread = NULL; > - > - QEMU_LOCK_GUARD(&migration_threads_lock); > - QLIST_FOREACH(thread, &migration_threads, node) { > - MigrationThreadInfo *info = g_new0(MigrationThreadInfo, 1); > - info->name = g_strdup(thread->name); > - info->thread_id = thread->thread_id; > - > - QAPI_LIST_APPEND(tail, info); > - } > - > - return head; > -} > diff --git a/migration/meson.build b/migration/meson.build > index 66d3de86f0..28a680e5e2 100644 > --- a/migration/meson.build > +++ b/migration/meson.build > @@ -29,7 +29,6 @@ system_ss.add(files( > 'savevm.c', > 'socket.c', > 'tls.c', > - 'threadinfo.c', > ), gnutls, zlib) > > if get_option('replication').allowed() > -- > 2.45.0 > -- -----Open up your eyes, open up your mind, open up your code ------- / Dr. David Alan Gilbert | Running GNU/Linux | Happy \ \ dave @ treblig.org | | In Hex / \ _________________________|_____ http://www.treblig.org |_______/
