On 4/13/21 5:01 PM, Alex Kogan wrote:
Hi, Andi.
Thanks for your comments!
On Apr 13, 2021, at 2:03 AM, Andi Kleen <ak@xxxxxxxxxxxxxxx> wrote:
Alex Kogan <alex.kogan@xxxxxxxxxx> writes:
+ numa_spinlock_threshold= [NUMA, PV_OPS]
+ Set the time threshold in milliseconds for the
+ number of intra-node lock hand-offs before the
+ NUMA-aware spinlock is forced to be passed to
+ a thread on another NUMA node. Valid values
+ are in the [1..100] range. Smaller values result
+ in a more fair, but less performant spinlock,
+ and vice versa. The default value is 10.
ms granularity seems very coarse grained for this. Surely
at some point of spinning you can afford a ktime_get? But ok.
We are reading time when we are at the head of the (main) queue, but
don’t have the lock yet. Not sure about the latency of ktime_get(), but
anything reasonably fast but not necessarily precise should work.
Could you turn that into a moduleparm which can be changed at runtime?
Would be strange to have to reboot just to play with this parameter
Yes, good suggestion, thanks.
This would also make the code a lot shorter I guess.
So you don’t think we need the command-line parameter, just the module_param?
The CNA code, if enabled, will be in vmlinux, not in a kernel module. As
a result, I think a module parameter will be no different from a kernel
command line parameter in this regard.
Cheers,
Longman
