Two important arguments in RTT estimation, mrtt and srtt, are passed to tcp_bpf_rtt(), so that bpf programs get more information about RTT computation in BPF_SOCK_OPS_RTT_CB. The difference between bpf_sock_ops->srtt_us and the srtt here is: the former is an old rtt before update, while srtt passed by tcp_bpf_rtt() is that after update.
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| @@ -6947,6 +6947,8 @@ enum { · 6946 unmodified lines | ||
| 6947 | 6947 | * socket transition to LISTEN state. |
| 6948 | 6948 | */ |
| 6949 | 6949 | BPF_SOCK_OPS_RTT_CB, /* Called on every RTT. |
| 6950 | + * Arg1: measured RTT input (mrtt) | |
| 6951 | + * Arg2: updated srtt | |
| 6950 | 6952 | */ |
| 6951 | 6953 | BPF_SOCK_OPS_PARSE_HDR_OPT_CB, /* Parse the header option. |
| 6952 | 6954 | * It will be called to handle |