[Qemu-devel] [PATCH 19/23] userfaultfd: activate syscall

[Dr. David Alan Gilbert]

* Bharata B Rao (bharata at linux.vnet.ibm.com) wrote:
> On Tue, Sep 08, 2015 at 09:59:47AM +0100, Dr. David Alan Gilbert wrote:
> > * Bharata B Rao (bharata at linux.vnet.ibm.com) wrote:
> > > In fact I had successfully done postcopy migration of sPAPR guest with
> > > this setup.
> > 
> > Interesting - I'd not got that far myself on power; I was hitting a problem
> > loading htab ( htab_load() bad index 2113929216 (14848+0 entries) in htab stream (htab_shift=25) )
> > 
> > Did you have to make any changes to the qemu code to get that happy?
> 
> I should have mentioned that I tried only QEMU driven migration within
> the same host using wp3-postcopy branch of your tree. I don't see the
> above issue.
> 
> (qemu) info migrate
> capabilities: xbzrle: off rdma-pin-all: off auto-converge: off zero-blocks: off compress: off x-postcopy-ram: on 
> Migration status: completed
> total time: 39432 milliseconds
> downtime: 162 milliseconds
> setup: 14 milliseconds
> transferred ram: 1297209 kbytes
> throughput: 270.72 mbps
> remaining ram: 0 kbytes
> total ram: 4194560 kbytes
> duplicate: 734015 pages
> skipped: 0 pages
> normal: 318469 pages
> normal bytes: 1273876 kbytes
> dirty sync count: 4
> 
> I will try migration between different hosts soon and check.

I hit that on the same host; are you sure you've switched into postcopy mode;
i.e. issued a migrate_start_postcopy before the end of migration?

(My current world I have working on x86-64 and I've also tested reasonably well
on aarch64, and get to that htab problem on Power).

Dave

> 
> Regards,
> Bharata.
> 
--
Dr. David Alan Gilbert / dgilbert at redhat.com / Manchester, UK