Re: [PATCH 0/3][RFC] NUMA: add host side pinning

[Anthony Liguori <anthony@codemonkey.ws>]

On 06/24/2010 06:12 AM, Avi Kivity wrote:
> On 06/24/2010 01:58 PM, Andre Przywara wrote:
>>> So who would create the /dev/shm/nodeXX files?
>>
>> Currently it is QEMU. It creates a somewhat unique filename, opens 
>> and unlinks it. The difference would be to name the file after the 
>> option and to not unlink it.
>>
>> > I can imagine starting numactl before qemu, even though that's
>> > cumbersome. I don't think it's feasible to start numactl after
>> > qemu is running. That'd involve way too much magic that I'd prefer
>> > qemu to call numactl itself.
>> Using the current code the files would not exist before QEMU 
>> allocated RAM, and after that it could already touch pages before 
>> numactl set the policy.
>
> Non-anonymous memory doesn't work well with ksm and transparent 
> hugepages.  Is it possible to use anonymous memory rather than file 
> backed?

You aren't going to be doing NUMA pinning and KSM AFAICT.

Regards,

Anthony Liguori

>> To avoid this I'd like to see the pinning done from within QEMU. I am 
>> not sure whether calling numactl via system() and friends is OK, I'd 
>> prefer to run the syscalls directly (like in patch 3/3) and pull the 
>> necessary options into the -numa pin,... command line. We could mimic 
>> numactl's syntax here.
>
> Definitely not use system(), but IIRC numactl has a library interface?
>
>