[Qemu-devel] [PATCH 0/9] Incoming migration coroutine

[Paolo Bonzini <pbonzini@redhat.com>]

Juan,

here is the implementation of migration-in-a-coroutine, applying on top
of your recently-posted 41-patch series.  With these patches, the monitor
(and in the future the NBD server) is responsive during migration.

The first seven patches are just cleanups, only the last two
actually implement the feature.  They are the opposite change of the
nonblocking->blocking change that you implemented for the migration
thread.  However, the change is much simpler because we have no timers,
and because of the use of coroutines.

Without coroutines (and as in non-threaded migration), you have
to proceed in two steps: first collect data in a buffer, then
write it.  This lets you handle EAGAIN only at precise points in
buffered_flush/buffered_put_buffer, so that you can restart writing
in migrate_fd_put_notify.  This "checkpointing" is the reason why
QEMUFileBuffered exists.  With coroutines, you can just stop whenever
you want with qemu_coroutine_yield.  As soon as select tells you that you
can read, you'll re-enter directly in qemu_get_buffer, read more data
and pass it to the loading routines.

Thanks,

Paolo

Paolo Bonzini (9):
  migration: unify stdio-based QEMUFile operations
  migration: consolidate QEMUFile methods in a single QEMUFileOps struct
  migration: add qemu_get_fd
  migration: replace qemu_stdio_fd with qemu_get_fd
  migration: clean up server sockets and handlers before invoking process_incoming_migration
  migration: close socket QEMUFile from socket_close
  migration: move qemu_fclose to process_incoming_migration
  migration: handle EAGAIN while reading QEMUFile
  migration: move process_incoming_migration to a coroutine

 buffered_file.c  |  21 +++++--
 migration-exec.c |   5 +-
 migration-fd.c   |   3 +-
 migration-tcp.c  |  10 +--
 migration-unix.c |  10 +--
 migration.c      |  27 +++++++-
 qemu-file.h      |  23 ++++---
 savevm.c         | 188 ++++++++++++++++++++++++++++++++-----------------------
 8 file modificati, 181 inserzioni(+), 106 rimozioni(-)

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1.7.12