Re: [PATCH 0/6] refactor RDMA live migration based on rsocket API

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Jun 04, 2024 at 08:14:06PM +0800, Gonglei wrote:
> From: Jialin Wang <wangjialin23@huawei.com>
> 
> Hi,
> 
> This patch series attempts to refactor RDMA live migration by
> introducing a new QIOChannelRDMA class based on the rsocket API.
> 
> The /usr/include/rdma/rsocket.h provides a higher level rsocket API
> that is a 1-1 match of the normal kernel 'sockets' API, which hides the
> detail of rdma protocol into rsocket and allows us to add support for
> some modern features like multifd more easily.
> 
> Here is the previous discussion on refactoring RDMA live migration using
> the rsocket API:
> 
> https://lore.kernel.org/qemu-devel/20240328130255.52257-1-philmd@linaro.org/
> 
> We have encountered some bugs when using rsocket and plan to submit them to
> the rdma-core community.
> 
> In addition, the use of rsocket makes our programming more convenient,
> but it must be noted that this method introduces multiple memory copies,
> which can be imagined that there will be a certain performance degradation,
> hoping that friends with RDMA network cards can help verify, thank you!

So you didn't test it with an RDMA card?
You really should test with an RDMA card though, for correctness
as much as performance.


> Jialin Wang (6):
>   migration: remove RDMA live migration temporarily
>   io: add QIOChannelRDMA class
>   io/channel-rdma: support working in coroutine
>   tests/unit: add test-io-channel-rdma.c
>   migration: introduce new RDMA live migration
>   migration/rdma: support multifd for RDMA migration
> 
>  docs/rdma.txt                     |  420 ---
>  include/io/channel-rdma.h         |  165 ++
>  io/channel-rdma.c                 |  798 ++++++
>  io/meson.build                    |    1 +
>  io/trace-events                   |   14 +
>  meson.build                       |    6 -
>  migration/meson.build             |    3 +-
>  migration/migration-stats.c       |    5 +-
>  migration/migration-stats.h       |    4 -
>  migration/migration.c             |   13 +-
>  migration/migration.h             |    9 -
>  migration/multifd.c               |   10 +
>  migration/options.c               |   16 -
>  migration/options.h               |    2 -
>  migration/qemu-file.c             |    1 -
>  migration/ram.c                   |   90 +-
>  migration/rdma.c                  | 4205 +----------------------------
>  migration/rdma.h                  |   67 +-
>  migration/savevm.c                |    2 +-
>  migration/trace-events            |   68 +-
>  qapi/migration.json               |   13 +-
>  scripts/analyze-migration.py      |    3 -
>  tests/unit/meson.build            |    1 +
>  tests/unit/test-io-channel-rdma.c |  276 ++
>  24 files changed, 1360 insertions(+), 4832 deletions(-)
>  delete mode 100644 docs/rdma.txt
>  create mode 100644 include/io/channel-rdma.h
>  create mode 100644 io/channel-rdma.c
>  create mode 100644 tests/unit/test-io-channel-rdma.c
> 
> -- 
> 2.43.0