Re: [Qemu-devel] post-copy is broken?

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

* Andrea Arcangeli (aarcange@redhat.com) wrote:
> On Fri, Apr 15, 2016 at 06:23:30PM +0300, Kirill A. Shutemov wrote:
> > The same here. Freshly booted machine with 64GiB ram. I've checked
> > /proc/vmstat: huge pages were allocated
> 
> I tried the test in a loop and I can't reproduce it here.
> 
> Tested with gcc 4.9.3 and glibc 2.21 and glibc 2.22 so far,
> qemu&kernel/KVM latest upstream (4.6-rc3..).
> 
> You can run this in between each invocation to guarantee all memory is
> backed by THP (no need of reboot):
> 
> # echo 3 >/proc/sys/vm/drop_caches
> # echo >/proc/sys/vm/compact_memory
> 
> 4.5 kernel built with gcc 5.3.1 run on a older userland worked fine
> too.
> 
> Next thing to test would be if there's something wrong with qemu built
> with gcc 5.3.1 if run on top of a 4.4 kernel?

It's also working for me on f24 (4.5.0-320 packaged kernel) on a real machine;
so we currently have two sets that break:

   a) Liang Li's setup (that breaks with the migrate of a real VM but I don't
                        think we have any details of the setup);
                        works with 4.4.x breaks with 4.5.x

   b) f24 nested with my test, with THP enabled after Kirill's changes.

Dave

--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK