Re: [Qemu-devel] [Qemu-ppc] [PATCH RFC v1 0/3] Enable MTTCG on PPC64

[G 3]

On Apr 6, 2017, at 9:32 AM, Cédric Le Goater wrote:

> On 04/06/2017 03:28 PM, G 3 wrote:
> > On Apr 6, 2017, at 9:26 AM, Cédric Le Goater wrote:
> >
> > > Hello Nikunj,
> > >
> > > On 04/06/2017 12:22 PM, Nikunj A Dadhania wrote:
> > > > The series enables Multi-Threaded TCG on PPC64
> > > >
> > > > Patch 01: Use atomic_cmpxchg in store conditional
> > > >       02: Handle first write to page during atomic operation
> > > >       03: Generate memory barriers for sync/isync and load/store  
> > > > conditional
> > > >
> > > > Patches are based on ppc-for-2.10
> > > >
> > > > Tested using following:
> > > > ./ppc64-softmmu/qemu-system-ppc64 -cpu POWER8 -vga none - 
> > > > nographic -machine pseries,usb=off -m 2G  -smp  
> > > > 8,cores=8,threads=1 -accel tcg,thread=multi  f23.img
> > >
> > > I tried it with a Ubuntu 16.04.2 guest using stress --cpu 8. It  
> > > looked
> > > good : the CPU usage of QEMU reached 760% on the host.
> >
> > What was your guest operating system?
>
> The guest is an Ubuntu 16.04.2 and the host is an Ubuntu 17.04.
>
> C.

Thank you for the information.

What you could do is run QEMU in emulation mode (non-kvm mode) and  
time how long it takes Ubuntu to boot up with one emulated core vs  
how long it takes to boot up on say 4 emulated cores. This would be a  
good start:

Boot up times:

one core:

two cores:

four cores:

eight cores: