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

[Cédric Le Goater]

On 04/07/2017 08:07 AM, Cédric Le Goater wrote:
> On 04/07/2017 07:24 AM, Nikunj A Dadhania wrote:
>> 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)
> 
> ok. I get it. Thanks,
> 
>>> and the PowerNV machine ?
>>
>> Haven't tried it, should work. Just give a shot, let me know if you see 
>> problems.
> 
> sure. pnv is still on 2.9, so I will rebase on 2.10, merge your 
> patches  and tell you.

The system seems to be spinning in skiboot in cpu_idle/relax when 
starting the linux kernel. It finally boots, but it is rather long.
David has merged enough to test if you want to give it a try.

Cheers,

C.