On 05/22/2012 06:56 AM, Orit Wasserman wrote: > Signed-off-by: Orit Wasserman <owass...@redhat.com> > --- > docs/xbzrle.txt | 114 > +++++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 files changed, 114 insertions(+), 0 deletions(-) > create mode 100644 docs/xbzrle.txt > > diff --git a/docs/xbzrle.txt b/docs/xbzrle.txt > new file mode 100644 > index 0000000..16950d5 > --- /dev/null > +++ b/docs/xbzrle.txt > @@ -0,0 +1,114 @@ > +XBZRLE (Xor Based Zero Run Length Encoding) > +=========================================== > + > +Using XBZRLE (Xor Based Zero Run Length Encoding) allows for the reduction > of VM > +downtime and the total live-migration time of Virtual machines. > +It is particularly useful for virtual machines running memory write intensive > +workloads that are typical of large enterprise applications such as SAP ERP > +Systems, and generally speaking for any application that uses a sparse memory > +update pattern. > + > +Instead of sending the changed guest memory page this solution will send a > +compressed version of the updates, thus reducing the amount of data sent > during > +live migration. > +In order to be able to calculate the update, the previous memory pages > needed to
s/needed/need/ > +be stored. Those pages are stored in a dedicated cache (hash table) and are s/stored./stored on the source./ > +Format > +======= > + > +The compression format uses the zero value, where zero represents an > unchanged > +value. s/uses the zero value/performs an XOR between the previous and current content of the page/ -- Eric Blake ebl...@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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