Re: [Qemu-devel] [PATCH v3 0/4] Introduce the microvm machine type

[Michael S. Tsirkin]

On Thu, Jul 25, 2019 at 04:13:13PM +0200, Paolo Bonzini wrote:
> On 25/07/19 15:54, Michael S. Tsirkin wrote:
> >> FWIW the "PCI tax" seems to be ~10 ms in QEMU, ~10 ms in the firmware(*)
> >> and ~25 ms in the kernel.
> > How did you measure the qemu time btw?
> > 
> 
> It's QEMU startup, but not QEMU altogether.  For example the time spent
> in memory.c when a BAR is programmed is not part of those 10 ms.
> 
> So I just computed q35 qemu startup - microvm qemu startup, it's 65 vs
> 65 ms.
> 
> Paolo

Oh so it could be eventfd or whatever, just as well.

I actually wonder whether we spend much time within
synchronize_* calls. eventfd triggers this a  lot of times.

How about ioeventfd=off? Does this speed up things?



-- 
MST