On 04/21/2013 03:17 PM, mrhi...@linux.vnet.ibm.com wrote: > From: "Michael R. Hines" <mrhi...@us.ibm.com> > > This functions allows you to perform your own per-QEMUFileOps > calculation for the value of 'max_size'. > > For RDMA, this calculation artificially limits migration throughput > and needs to be done differently for high-throughput links. > > Signed-off-by: Michael R. Hines <mrhi...@us.ibm.com> > ---
>
> +size_t qemu_get_max_size(QEMUFile *f, uint64_t transferred_bytes,
> + uint64_t time_spent, uint64_t max_downtime)
> +{
> + if (time_spent) {
> + mbps = (((double) transferred_bytes * 8.0) /
> + ((double) time_spent / 1000.0)) / 1000.0 / 1000.0;
> + } else {
> + mbps = -1.0;
> + }
> +
> + if (f->ops->get_max_size) {
> + return f->ops->get_max_size(f, f->opaque,
> + transferred_bytes, time_spent, max_downtime);
> + }
> +
> + return ((double) (transferred_bytes / time_spent)) *
> + max_downtime / 1000000;
Cast to double is too late; you've already suffered from integer
division truncation when you compute (transferred_bytes/time_spent).
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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