xiangxia.m.yue@xxxxxxxxx writes: > From: Tonghao Zhang <xiangxia.m.yue@xxxxxxxxx> > > This patch introduce a new bpf_ktime_get_real_ns helper, which may > help us to measure the skb latency in the ingress/forwarding path: > > HW/SW[1] -> ip_rcv/tcp_rcv_established -> tcp_recvmsg_locked/tcp_update_recv_tstamps > > * Insert BPF kprobe into ip_rcv/tcp_rcv_established invoking this helper. > Then we can inspect how long time elapsed since HW/SW. > * If inserting BPF kprobe tcp_update_recv_tstamps invoked by tcp_recvmsg, > we can measure how much latency skb in tcp receive queue. The reason for > this can be application fetch the TCP messages too late. Why not just use one of the existing ktime helpers and also add a BPF probe to set the initial timestamp instead of relying on skb->tstamp? -Toke
