tcp 相关的内核变量

/proc/sys/net/ipv4下这么多tcp 相关的内核变量，都有什么用处呢？

[vagrant@localhost ipv4]$ ll | grep tcp | awk '{key=$9; "cat " $9 | getline output; print key,"----", output}'tcp_abort_on_overflow ---- 0tcp_adv_win_scale ---- 1tcp_allowed_congestion_control ---- cubic renotcp_app_win ---- 31tcp_autocorking ---- 1tcp_available_congestion_control ---- cubic renotcp_base_mss ---- 512tcp_challenge_ack_limit ---- 100tcp_congestion_control ---- cubictcp_dsack ---- 1tcp_early_retrans ---- 3tcp_ecn ---- 2tcp_fack ---- 1tcp_fastopen ---- 0cat: tcp_fastopen_key: 权限不够tcp_fastopen_key ---- 0tcp_fin_timeout ---- 60tcp_frto ---- 2tcp_invalid_ratelimit ---- 500tcp_keepalive_intvl ---- 75tcp_keepalive_probes ---- 9tcp_keepalive_time ---- 7200tcp_limit_output_bytes ---- 262144tcp_low_latency ---- 0tcp_max_orphans ---- 2048tcp_max_ssthresh ---- 0tcp_max_syn_backlog ---- 128tcp_max_tw_buckets ---- 2048tcp_mem ---- 11607  15476   23214tcp_min_tso_segs ---- 2tcp_moderate_rcvbuf ---- 1tcp_mtu_probing ---- 0tcp_no_metrics_save ---- 0tcp_notsent_lowat ---- -1tcp_orphan_retries ---- 0tcp_reordering ---- 3tcp_retrans_collapse ---- 1tcp_retries1 ---- 3tcp_retries2 ---- 15tcp_rfc1337 ---- 0tcp_rmem ---- 4096  87380   3846112tcp_sack ---- 1tcp_slow_start_after_idle ---- 1tcp_stdurg ---- 0tcp_synack_retries ---- 5tcp_syncookies ---- 1tcp_syn_retries ---- 6tcp_thin_dupack ---- 0tcp_thin_linear_timeouts ---- 0tcp_timestamps ---- 1tcp_tso_win_divisor ---- 3tcp_tw_recycle ---- 0tcp_tw_reuse ---- 0tcp_window_scaling ---- 1tcp_wmem ---- 4096  16384   3846112tcp_workaround_signed_windows ---- 0[vagrant@localhost ipv4]$ pwd/proc/sys/net/ipv4