Re: [PATCH v9 0/5] Add NUMA-awareness to qspinlock

Paul E. McKenney
2020-01-25T04:58:49Z

On Fri, Jan 24, 2020 at 09:17:05PM -0500, Waiman Long wrote:
> On 1/24/20 8:59 PM, Waiman Long wrote:
> >> You called it! I will play with QEMU's -numa argument to see if I can get
> >> CNA to run for me. Please accept my apologies for the false alarm.
> >>
> >> Thanx, Paul
> >>
> > CNA is not currently supported in a VM guest simply because the numa
> > information is not reliable. You will have to run it on baremetal to
> > test it. Sorry for that.
>
> Correction. There is a command line option to force CNA lock to be used
> in a VM. Use the "numa_spinlock=on" boot command line parameter.

As I understand it, I need to use a series of -numa arguments to qemu
combined with the numa_spinlock=on (or =1) on the kernel command line.
If the kernel thinks that there is only one NUMA node, it appears to
avoid doing CNA.

Correct?

Thanx, Paul