Unable to utilize 400 Gb/s DRBD link with single resource using DRBD’s CPU mask

[AntonHPE]

Hello

According to the user guide,

"DRBD allows you to set an explicit CPU mask for its kernel threads. By default, DRBD picks a single CPU for each resource. All the threads for this resource run on this CPU. This policy is generally optimal when the goal is maximum aggregate performance with more DRBD resources than CPU cores. If instead you want to maximize the performance of individual resources at the cost of total CPU usage, you can use the CPU mask parameter to allow the DRBD threads to use multiple CPUs."

Test DRBD resource has,

resource test {
options {
cpu-mask 0000ffff;
}

But looks it still uses single core on Primary and Secondary servers, limiting replication bandwidth up to ~4GByte/s, no matter TCP or RDMA Test environment completely idle.
Hardware - 400 Gb/s dedicated link for DRBD, PCIe 5.0. NVMe SSDs, AMD EPYC 9455P 48-Core.

So, how let DRBD utilize modern hardware keeping all replication volumes with single DRBD resource ?