[Qemu-devel] how to create threads like dataplane in qemu

[Qemu-devel] how to create threads like dataplane in qemu

[PERSIST]

Hello!
  I want to create a specific thread for each process in VM so that virtio block requests from each process can be sumbitted in the thread related to the process.
  I tried to implement it by referring to dataplane,but I can not understand the source about dataplane.
  What should I do?

  I am not good at English.Please forgive me.

  Best wishes
                                                            Zhiheng Tao

Re: [Qemu-devel] how to create threads like dataplane in qemu

[Fam Zheng]

On Sat, 04/01 11:54, PERSIST wrote:
> Hello!
>   I want to create a specific thread for each process in VM so that virtio block requests from each process can be sumbitted in the thread related to the process.
>   I tried to implement it by referring to dataplane,but I can not understand the source about dataplane.

There are multiple abstraction layers between guest process and QEMU threads, I
don't think the model you describe is practical. In dataplane, requests are
submitted to host through virtio ioeventfd, and handled by the per-virtual
device thread. What are you trying to achieve here?

Fam

Re: [Qemu-devel] how to create threads like dataplane in qemu

[Stefan Hajnoczi]

[-- Attachment #1: Type: text/plain, Size: 985 bytes --]

On Sat, Apr 01, 2017 at 11:54:35AM +0800, PERSIST wrote:
>   I want to create a specific thread for each process in VM so that virtio block requests from each process can be sumbitted in the thread related to the process.
>   I tried to implement it by referring to dataplane,but I can not understand the source about dataplane.
>   What should I do?

It sounds like QEMU can already do what you want:

1. Define -object iothread for each guest process that needs a
   dedicated dataplane thread.
2. Define -device virtio-blk-pci,iothread=iothread for each block
   device.  It wasn't clear from your email but I'm assuming here that
   every guest process operates on its own disk image file.  QEMU does
   not support true multiqueue disk I/O to a single image file yet.

You should also bind the iothreads to host logical CPUs, bind vcpu
threads to host logical CPUs, and bind the guest processes to vcpus.
That way each guest process has a dedicated host CPU and iothread.

Stefan

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 455 bytes --]