Re: [Qemu-devel] SMP and qemu scheduler, HELP

[françois Guerret]

Hello,

Thanks for your concern.

I want to execute a realtime software which executes periodically the same loop.

On multicore target, I set one periodic loop per core.

I need the time to be synchronized between the cores at least with the granularity of a loop period.

For instance I want to prevent core 0 to execute three time its loop while core 1 executes its own once.

Moreover I want to use *time* (icount time) to synchornize the loops (hence a barrier using an active waiting

is definitly not a good solution). Indeed I need the icount time necessary to execute the loop to be more or less constant.

I hope these explanations will enable you to help me.

Thanks in advance

Francois

> From: address@hidden
> Date: Mon, 24 Aug 2015 16:52:04 +0100
> Subject: Re: [Qemu-devel] SMP and qemu scheduler, HELP
> To: address@hidden
> CC: address@hidden
>
> On 24 August 2015 at 11:03, françois Guerret
> <address@hidden> wrote:
> > Hello,
> >
> > I use qemu to emulate a SMP multicore processor and I am looking for a way :
> > * either to ask qemu scheduler to execute an other core. For that I need a
> > kind of
> > *yield()* syscall that I could insert into user code and which would be
> > catched by
> > QEMU scheduler.
> > * or to give an option to QEMU to control the sheduling period. I would
> > like to be
> > able to tell qemu that I need every core to be executed at least every
> > 1 ms
> > (in icount time mode) for instance.
>
>
> It would be interesting if you could explain why you want these features.
>
> thanks
> -- PMM