Re: [PATCH] migration/throttle: Add throttle-trig-thres migration parameter

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Eric Blake (eblake@redhat.com) wrote:
> On 2/20/20 8:57 PM, Keqian Zhu wrote:
> > Currently, if the bytes_dirty_period is more than the 50% of
> > bytes_xfer_period, we start or increase throttling.
> > 
> > If we make this percentage higher, then we can tolerate higher
> > dirty rate during migration, which means less impact on guest.
> > The side effect of higher percentage is longer migration time.
> > 
> > We can configure this parameter to switch between migration time
> > firt or guest performance first. The default value is 50.
> > 
> > Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
> > ---
> > Cc: Juan Quintela <quintela@redhat.com>
> > Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > Cc: Eric Blake <eblake@redhat.com>
> > Cc: Markus Armbruster <armbru@redhat.com>
> > ---
> 
> > +++ b/qapi/migration.json
> > @@ -524,6 +524,10 @@
> >   #                      compression, so set the decompress-threads to the number about 1/4
> >   #                      of compress-threads is adequate.
> >   #
> > +# @throttle-trig-thres: The ratio of bytes_dirty_period and bytes_xfer_period to
> > +#                       trigger throttling. It is expressed as percentage. The
> > +#                       default value is 50. (Since 5.0)
> > +#
> 
> Abbreviating feels odd; can you please spell this out as
> throttle-trigger-threshold?
> 
> Can the threshold exceed 100%?

Note the code checks for that and disallows it, only allowing 1..99

Dave

> 
> -- 
> Eric Blake, Principal Software Engineer
> Red Hat, Inc.           +1-919-301-3226
> Virtualization:  qemu.org | libvirt.org
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK