Re: [Qemu-devel] Why I advise against using ivshmem

[Claudio Fontana]

On 17.06.2014 11:03, David Marchand wrote:
> Hello all,
> 
> On 06/17/2014 04:54 AM, Stefan Hajnoczi wrote:
>> ivshmem has a performance disadvantage for guest-to-host
>> communication.  Since the shared memory is exposed as PCI BARs, the
>> guest has to memcpy into the shared memory.
>>
>> vhost-user can access guest memory directly and avoid the copy inside the 
>> guest.
> 
> Actually, you can avoid this memory copy using frameworks like DPDK.
> 
> 
>> Unless someone steps up and maintains ivshmem, I think it should be
>> deprecated and dropped from QEMU.
> 
> Then I can maintain ivshmem for QEMU.
> If this is ok, I will send a patch for MAINTAINERS file.
> 
> 

Just a +1 over here for the need of a guest to guest shared memory solution.

There are several internal requirements for that, and I saw this discussion 
just about when starting to build on top of nahanni/ivshmem.

In general what I'd like to see is for ivshmem (or any other guest-guest shared 
memory communication solution)
to get consolidated into the QEMU codebase, and not having to pick and choose 
pieces from different repositories.
vhost-user is interesting and welcome, however guest-host communication is not 
the use case I have over here at the moment.

Ciao,

Claudio