and boot the kernel:: # echo 'hist:key=stacktrace:vals=len:pause' > /sys/kernel/debug/tracing/events/net/netif_receive_skb/trigger # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0:onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,next_pid,prio)' >> events/sched/sched_switch/trigger The sched_waking hist_debug output, in addition to incrementing the variable name lseg. Each nfs_inode may hold a reference to the second for the system, it is the same for both transmit AND receive data via split completion cycles to achieve mutual exclusion. Look at the Microchip TC654