On Fri, Mar 19, 2021 at 05:52:47PM +0300, Andrey Gruzdev wrote:
> Added missing qemu_fflush() on buffer file holding precopy device state.
> Increased initial QIOChannelBuffer allocation to 512KB to avoid reallocs.
> Typical configurations often require >200KB for device state and VMDESC.
>
> Signed-off-by: Andrey Gruzdev <andrey.gruz...@virtuozzo.com>
> ---
> migration/migration.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index ca8b97baa5..32b48fe9f5 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -3812,7 +3812,7 @@ static void *bg_migration_thread(void *opaque)
> * with vCPUs running and, finally, write stashed non-RAM part of
> * the vmstate from the buffer to the migration stream.
> */
> - s->bioc = qio_channel_buffer_new(128 * 1024);
> + s->bioc = qio_channel_buffer_new(512 * 1024);
> qio_channel_set_name(QIO_CHANNEL(s->bioc), "vmstate-buffer");
> fb = qemu_fopen_channel_output(QIO_CHANNEL(s->bioc));
> object_unref(OBJECT(s->bioc));
> @@ -3866,6 +3866,8 @@ static void *bg_migration_thread(void *opaque)
> if (qemu_savevm_state_complete_precopy_non_iterable(fb, false, false)) {
> goto fail;
> }
> + qemu_fflush(fb);
What will happen if the vmstates are bigger than 512KB? Would the extra data
be dropped?
In that case, I'm wondering whether we'll need a qemu_file_get_error() after
the flush to detect it, and whether we need to retry with a bigger buffer size?
Thanks,
--
Peter Xu
