On 29-Jan-21 10:05 AM, Bruce Richardson wrote:
On Thu, Jan 28, 2021 at 04:07:07AM +0000, Oscar Zhao wrote:
Hello dpdk devs,
I would like to discuss the feasibility of implementing CPU topology detection
on FreeBSD. Currently both eal_cpu_core_id() and eal_cpu_socket_id() in rte_eal
library always return 0 on FreeBSD, making NUMA-aware development impossible
without resorting to external libraries or system APIs.
The CPU topology information is available via sysct kern.sched.topology_spec.
The only issue is that the return value is an XML formatted object (see
https://forums.freebsd.org/threads/number-of-cpus-and-cores.41299/).
(https://forums.freebsd.org/threads/number-of-cpus-and-cores.41299/) I'm not
sure how feasible it is to parse XML inside DPDK.
On a side note, obtaining the physical NUMA node id of a core is easy - sysctl
dev.cpu.[cpu#].%domain returns the corresponding node id but I have yet found a
straightforward way to detect hyperthreads besides the XML thing.
Oscar
Even adding in the numa node information would be a welcome start.
There's little value in it though, because as far as i'm aware we can't
allocate memory on specific NUMA nodes in FreeBSD.
--
Thanks,
Anatoly
