Re: [Qemu-devel] [PATCH QEMU 5/5] migration: Add the interface for cache drop control

[Li, Liang Z]

> Sent: Tuesday, April 19, 2016 10:52 PM
> To: Li, Liang Z; address@hidden; address@hidden;
> address@hidden; address@hidden; address@hidden
> Cc: address@hidden; address@hidden;
> address@hidden; address@hidden; address@hidden;
> address@hidden; address@hidden; address@hidden;
> address@hidden; address@hidden; address@hidden;
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> Subject: Re: [Qemu-devel] [PATCH QEMU 5/5] migration: Add the interface
> for cache drop control
> 
> On 04/19/2016 08:20 AM, Liang Li wrote:
> > Whether drop the cache and drop what kind of cache depend on the
> 
> Whether to drop the cache, and what kind of cache drop to perform,
> depend ...
> 
> > user, add the related qmp and hmp interface to query and set the cache
> > control value.
> >
> > Signed-off-by: Liang Li <address@hidden>
> > ---
> 
> > +++ b/qapi-schema.json
> > @@ -612,11 +612,21 @@
> >  # @x-cpu-throttle-increment: throttle percentage increase each time
> >  #                            auto-converge detects that migration is not 
> > making
> >  #                            progress. The default value is 10. (Since 2.5)
> > +# @x-drop-cache: drop guest's page cache during live migration, the value
> can
> > +#         be set to 0, 1, 2, 3. 1 means drop the clean page cache, 2 means
> > +#         drop the slab cache, 3 means to drop both clean page cache, 0
> means
> > +#         do not drop any cache. Drop cache can speed up live migration
> > +#         process and reduce the network traffic, the side affect is the
> > +#         performance impact to the guest, 1 is the recommended value for
> > +#         proper balance between speed and performance. The value only
> takes
> > +#         affect when the virtio-balloon device are enabled and the guest
> > +#         has the related driver. The default value is 0. (Since 2.7)
> 
> Absolutely not this interface.  Make this an enum type, not a raw magic-
> number integer type, where the user requests "x-drop-cache":"clean", "x-
> drop-cache":"slab", and so on.
> 

The enum type looks better, thanks!

Liang
> --
> Eric Blake   eblake redhat com    +1-919-301-3266
> Libvirt virtualization library http://libvirt.org