Re: [Qemu-devel] [PATCH v2 3/8] dump-guest-memory: add basic "detach" support.

[Peter Xu]

On Fri, Nov 27, 2015 at 11:14:17AM +0100, Paolo Bonzini wrote:
> 
> 
> On 27/11/2015 07:27, Peter Xu wrote:
> > If embed the mr pointer into GuestPhyBlock, then we might need to
> > ref/unref one MemoryRegion for multiple times (and I am not sure how
> > many, maybe it could be a very big number especially the
> > MemoryRegionSections are scattered?). Not sure whether it is more
> > efficient.
> > 
> > For what I see, the number of MemoryRegions should be not big (<5 in
> > my case). So even with O(N^2), it should merely like O(N). Not sure
> > about this too.
> > 
> > Would like to hear more review comments from Paolo and others.
> > 
> 
> Fam suggestion is a good one, ref'ing one MemoryRegion many times is not
> a problem.

Ok, then I will embed the MemoryRegion pointer into GuestPhysBlocks
in v3.

> 
> Also I noticed now that you do the dump_init in the main thread (using a
> listener), so the RCU lock/unlock is not needed.  I don't know this code
> very well.

Yes, it's in main thread too in v1 patch, since I think that should
not be the time consuming part. If so, I will remove the RCU
lock/unlock too.

> 
> It's worth adding a comment at the top of functions that are called from
> a separate thread.

Ok. Will add that.

Thanks!
Peter

> 
> Thanks,
> 
> Paolo