Re: [Qemu-devel] virtio-serial-pci very expensive during live migration

[Amit Shah]

On (Thu) 08 May 2014 [15:36:13], Paolo Bonzini wrote:
> Il 08/05/2014 15:30, Amit Shah ha scritto:
> >On (Thu) 08 May 2014 [15:14:26], Paolo Bonzini wrote:
> >>Il 08/05/2014 15:02, Amit Shah ha scritto:
> >>>>>I tried the patch below.  Unfortunately it seems to cause qemu to crash.
> >>>This doesn't remove the memory_region_transaction_begin() and
> >>>_commit() from memory_region_add_eventfd(), which will still be
> >>>called.
> >>
> >>That's correct, transactions can be nested.
> >
> >But each _commit() will add to the delay?
> 
> No, only the outermost one.

Helps to read the code :-)

Chris, I just tried a simple test this way:

./x86_64-softmmu/qemu-system-x86_64 -device virtio-serial-pci -device 
virtserialport -S -monitor stdio -nographic

and it didn't crash for me.  This was with qemu.git.  Perhaps you can
try in a similar way.


                Amit