[Qemu-devel] Queries on dataplane mechanism

[Gaurav Sharma]

Hi,
I am trying to explore how the data plane mechanism works in QEMU. I
understand the behavior of QEMU big lock. Can someone clarify the following
w.r.t. to data plane :

1. Currently only virtio-blk-pci and virtio-scsi-pci have data plane
enabled ?

2. From qemu 2.1.0 data plane is enabled by default. I specify the
following options in the command line to enable :
-enable-kvm -drive if=none,id=drive1,file=file_name -object
iothread,id=iothread2 -device
virtio-blk-pci,id=drv0,drive=drive1,iothread=iothread2
Is the above syntax correct ?

3. What is the best possible scenario to test data plane ? Currently, I
have a test set up wherein i have two different devices [dev1 and dev2]. If
i process a write to dev1 which i made blocking by putting a sleep
statement, will i be able to process write on dev2 ? My understanding is
that as in case of dataplane we have a different event loop, i should be
able to process write on dev2. Is this correct ?

I am using qemu 2.2.0 on CentOS 7.1 with kvm version 1.5.3 and using Debian
3.2.8 as guest OS.

Regards.