This is v5 patchset of modified 'migrate' and 'migrate-incoming' QAPI design
for upstream review.
Would like to thank all the maintainers that actively participated in the v4
patchset discussion and gave insightful suggestions to improve the patches.
Link to previous upstream community patchset links:
v1: https://lists.gnu.org/archive/html/qemu-devel/2022-12/msg04339.html
v2: https://lists.gnu.org/archive/html/qemu-devel/2023-02/msg02106.html
v3: https://lists.gnu.org/archive/html/qemu-devel/2023-02/msg02473.html
v4: https://lists.gnu.org/archive/html/qemu-devel/2023-05/msg03064.html
v4 -> v5 changelog:
-------------------
- Improved majorly on cleanly freeing objects across the patches by using
g_auto(), g_autoptr(), gnew0() macros wherever necessary and preventing
unecessary use goto statements.
- Simplified error statement propogation in migration code flow.
- qapi: changed version form 8.0 -> 8.1
- For HMP commands, decided to keep using URI syntax forever, so depricated
implementation of migrate_channel_from_qdict() for converting URI ->
MigrateChannel struct, as "char *uri" is already getting converted into
modified struct using another API in the workflow.
- Additional tcp test case for multifd with modified QAPI syntax in qtests.
Abstract:
---------
Current QAPI 'migrate' command design (for initiating a migration
stream) contains information regarding different migrate transport mechanism
(tcp / unix / exec), dest-host IP address, and binding port number in form of
a string. Thus the design does seem to have some design issues. Some of the
issues, stated below are:
1. Use of string URIs is a data encoding scheme within a data encoding scheme.
QEMU code should directly be able to work with the results from QAPI,
without resorting to do a second level of parsing (eg. socket_parse()).
2. For features / parameters related to migration, the migration tunables needs
to be defined and updated upfront. For example, 'migrate-set-capability'
and 'migrate-set-parameter' is required to enable multifd capability and
multifd-number of channels respectively. Instead, 'Multifd-channels' can
directly be represented as a single additional parameter to 'migrate'
QAPI. 'migrate-set-capability' and 'migrate-set-parameter' commands could
be used for runtime tunables that need setting after migration has already
started.
The current patchset focuses on solving the first problem of multi-level
encoding of URIs. The patch defines 'migrate' command as a QAPI discriminated
union for the various transport backends (like socket, exec and rdma), and on
basis of transport backends, different migration parameters are defined.
(uri) string --> (channel) Channel-type
Transport-type
Migration parameters based on transport type
------------------------------------------------------------------------------
Het Gala (9):
migration: introduced 'MigrateAddress' in QAPI for migration wire
protocol.
migration: convert uri parameter into 'MigrateAddress' struct
migration: convert socket backend to accept MigrateAddress struct
migration: convert rdma backend to accept MigrateAddress struct
migration: convert exec backend to accept MigrateAddress struct.
migration: modified migration QAPIs to accept 'channels' argument for
migration
migration: modify migration_channels_and_uri_compatible() to
incorporate newer migration QAPI syntax
migration: Introduced MigrateChannelList struct to migration code
flow.
migration: adding test case for modified QAPI syntax
migration/exec.c | 62 ++++++++---
migration/exec.h | 8 +-
migration/migration-hmp-cmds.c | 16 ++-
migration/migration.c | 183 ++++++++++++++++++++++++++-------
migration/rdma.c | 34 +++---
migration/rdma.h | 6 +-
migration/socket.c | 39 ++-----
migration/socket.h | 7 +-
qapi/migration.json | 145 +++++++++++++++++++++++++-
softmmu/vl.c | 2 +-
tests/qtest/migration-test.c | 47 +++++++++
11 files changed, 426 insertions(+), 123 deletions(-)
--
2.22.3