SMP IRQ Affinity in L4android

Hi, everyone I want to move some interrupts to specified cpu core, but I encountered some difficulties. When I try to write to "/proc/irq/*/smp_affinity" with cpu bitmask, it will call the interface l4lx_irq_dev_set_affinity(), which locates in "pots-foc/src/lib/l4lx/l4lx_irq.cc". And I can see the printed log "switched irq * to cpu* ". However, in fact, it doesnot work, the irq is still staying on previous cpu core ( seeing "/proc/interrupts") . Please tell me how can I do, thank you so much!