Re: [Qemu-devel] [PATCH] migration: adding migration to/from a file

[Anthony Liguori]

Daniel P. Berrange wrote:
> On Tue, Jan 20, 2009 at 01:32:24PM +0200, Uri Lublin wrote:
>   
> > I can call fcntl with F_SETFL and O_NONBLOCK.
> >     
>
> IIRC that doesn't have any effect on plain files - they'll still potentially
> block on write.
>   

Yes, it doesn't.  I learned this the hard way with the old migration 
code.  When I implemented file: migration, I noticed it never worked 
properly (properly being live) unless I used a rate limit.  Since we 
defaulted a rate limit, it seemed to work, but the true test is whether 
it works in the absence of rate limiting.

Regards,

Anthony Liguori

> Daniel
>