Re: [Qemu-devel] Migration dirty bitmap: should only mark pages as dirty after they have been sent

[Li, Liang Z]

> > I compare SHA1 with XBZRLE. I use XBZRLE in two ways:
> > 1. Begins to buffer pages from iteration 1; 2. As current
> > implementation, begins to buffer pages from iteration 2.
> >
> > I post the results of three workloads: cpu2006.zeusmp, cpu2006.mcf,
> > memcached.
> > I set the cache size as 256MB for zeusmp & mcf (they run in VM with
> > 1GB ram), and set the cache size as 1GB for memcached (it run in VM
> > with 6GB ram, and memcached takes 4GB as cache).
> >
> > As you can read from the data below, beginning to buffer pages from
> > iteration 1 is better than the current implementation(from iteration
> > 2), because the total migration time is shorter.
> >
> > SHA1 is better than the XBZRLE with the cache size I choose, because
> > it leads to shorter migration time, and consumes far less memory
> > overhead (<1/200 of the total VM memory).
> >
> 
> Hi Chunguang,
> 
> Have you tried to use a large XBZRLE cache size which equals to the guest's
> RAM size?
> Is SHA1 faster in that case?
> 
> Thanks!
> Liang

Intel's future chipset will contain hardware engines which supports SHA-x and 
MD5,
We can make use these engines to offload the overhead from CPU for SHA/MD5 
calculation.

Liang