On 1/24/20 11:58 PM, Paul E. McKenney wrote: > 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 > In auto-detection mode (the default), CNA will only be turned on when paravirt qspinlock is not enabled first and there are at least 2 numa nodes. The "numa_spinlock=on" option will force it on even when both of the above conditions are false. Cheers, Longman
