Re: [RFC 4/6] migration: Deprecate -incoming <uri>

Paolo Bonzini <pbonzini(a)redhat.com&gt; wrote: > On 6/22/23 10:52, Juan Quintela wrote: >> User friendliness. >> The problem is that if you use more than two channels with multifd, on >> the incoming side, you need to do: > > You're sacrificing user-friendliness for the 99.99% that don't use > multifd, for an error (i.e. it's not even fixing the issue) for the > 0.01% that use multifd. That's not user-friendly. You are forgeting of the 0.01% that uses postocopy preempt (that is easy just changing the default value to 2), and the 0.0000001% that uses compression (they have exactly the same problem with compress_threads, compress_zlib, etc). >> - migrate_set_parameter multifd-channels 16 >> - migrate_incoming <uri> >> >>> The issue is not how many features the command line has, but how >>> they're implemented. >> Or if they are confusing for the user? > > Anyone using multifd is not a typical user anyway. >>> If they're just QMP wrappers and as such they're self-contained in >>> softmmu/vl.c, that's fine. >>> >>> In fact, even for parameters, we could use keyval to parse "-incoming" >> What is keyval? > > util/keyval.c and include/qemu/keyval.h. It parses a list of > key=value pairs into a QDict. Once you have removed the "source" key > from the QDict you can use a visitor to parse the rest into a > MigrateSetParameters. See the handling of QEMU_OPTION_audio, it could > be something like > > > case QEMU_OPTION_incoing: { > Visitor *v; > MigrateSetParameters *incoming_params = NULL; > QDict *dict = keyval_parse(optarg, "source", NULL, > &error_fatal); > > if (incoming) { > if (qdict_haskey(dict, "source")) { > error_setg(&error_fatal, "Parameter 'source' > is duplicate"); > } > } else { > if (!qdict_haskey(dict, "source")) { > error_setg(&error_fatal, "Parameter 'source' > is missing"); > } > runstate_set(RUN_STATE_INMIGRATE); > incoming = g_strdup(qdict_get_str(dict, "source")); > qdict_del(dict, "source"); > } > > v = qobject_input_visitor_new_keyval(QOBJECT(dict)); > qobject_unref(dict); > visit_type_MigrateSetParameters(v, NULL, > &incoming_params, &error_fatal); > visit_free(v); > qmp_migration_set_parameters(incoming_params,

> &error_fatal); > qapi_free_MigrateSetParameters(incoming_params); > } > > > For example "-incoming [source=]tcp:foo,multifd-channels=16" would > desugar to > > migrate_set_parameter multifd-channels 16 > migrate_incoming tcp:foo > > The only incompatibility is for people who are using "," in an URI, > which is rare and only an issue for the "exec" protocol.

Aha, that makes sense. And will allow us to deprecate/remove the --global migration.* stuff.