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

[Nikunj A Dadhania]

Cédric Le Goater <address@hidden> writes:

> 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.

Cool.

>> Todo:
>> * Enable other machine types and PPC32.
>
> I am quite ignorant on the topic.
> Have you looked at what it would take to emulate support of the HW
> threads ?

We would need to implement msgsndp (doorbell support for IPI between
threads of same core)

> and the PowerNV machine ?

Haven't tried it, should work. Just give a shot, let me know if you see 
problems.

Regards
Nikunj