Re: [Qemu-devel] [PATCH] migration: Increase default max_downtime from 30ms to 300ms

[Markus Armbruster]

Adding Juan.

Alexey Kardashevskiy <address@hidden> writes:

> The existing timeout is 30ms which on 100MB/s (1Gbit) gives us
> 3MB/s rate maximum. If we put some load on the guest, it is easy to
> get page dirtying rate too big so live migration will never complete.
> In the case of libvirt that means that the guest will be stopped
> anyway after a timeout specified in the "virsh migrate" command and
> this normally generates even bigger delay.
>
> This changes max_downtime to 300ms which seems to be more
> reasonable value.
>
> Signed-off-by: Alexey Kardashevskiy <address@hidden>
> ---
>  migration.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/migration.c b/migration.c
> index e0e24d4..02bbce9 100644
> --- a/migration.c
> +++ b/migration.c
> @@ -144,7 +144,7 @@ void process_incoming_migration(QEMUFile *f)
>   * the choice of nanoseconds is because it is the maximum resolution that
>   * get_clock() can achieve. It is an internal measure. All user-visible
>   * units must be in seconds */
> -static uint64_t max_downtime = 30000000;
> +static uint64_t max_downtime = 300000000;
>  
>  uint64_t migrate_max_downtime(void)
>  {