Date: Thu, 24 Oct 2019 05:54:30 +0000 (UTC) From: Randall Stewart <rrs@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r354013 - head/sys/netinet/tcp_stacks Message-ID: <201910240554.x9O5sU46008191@repo.freebsd.org>
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Author: rrs Date: Thu Oct 24 05:54:30 2019 New Revision: 354013 URL: https://svnweb.freebsd.org/changeset/base/354013 Log: Fix a small bug in bbr when running under a VM. Basically what happens is we are more delayed in the pacer calling in so we remove the stack from the pacer and recalculate how much time is left after all data has been acknowledged. However the comparision was backwards so we end up with a negative value in the last_pacing_delay time which causes us to add in a huge value to the next pacing time thus stalling the connection. Reported by: vm2.finance@gmail.com Modified: head/sys/netinet/tcp_stacks/bbr.c Modified: head/sys/netinet/tcp_stacks/bbr.c ============================================================================== --- head/sys/netinet/tcp_stacks/bbr.c Thu Oct 24 04:12:38 2019 (r354012) +++ head/sys/netinet/tcp_stacks/bbr.c Thu Oct 24 05:54:30 2019 (r354013) @@ -11814,12 +11814,13 @@ bbr_do_segment_nounlock(struct mbuf *m, struct tcphdr uint32_t del; del = lcts - bbr->rc_pacer_started; - if (del > bbr->r_ctl.rc_last_delay_val) { + if (bbr->r_ctl.rc_last_delay_val > del) { BBR_STAT_INC(bbr_force_timer_start); bbr->r_ctl.rc_last_delay_val -= del; bbr->rc_pacer_started = lcts; } else { /* We are late */ + bbr->r_ctl.rc_last_delay_val = 0; BBR_STAT_INC(bbr_force_output); (void)tp->t_fb->tfb_tcp_output(tp); } @@ -12278,8 +12279,9 @@ bbr_output_wtime(struct tcpcb *tp, const struct timeva * We are early setup to adjust * our slot time. */ + uint64_t merged_val; + bbr->r_ctl.rc_agg_early += (bbr->r_ctl.rc_last_delay_val - delay_calc); - bbr->r_ctl.rc_last_delay_val = 0; bbr->r_agg_early_set = 1; if (bbr->r_ctl.rc_hptsi_agg_delay) { if (bbr->r_ctl.rc_hptsi_agg_delay >= bbr->r_ctl.rc_agg_early) { @@ -12292,9 +12294,13 @@ bbr_output_wtime(struct tcpcb *tp, const struct timeva bbr->r_ctl.rc_hptsi_agg_delay = 0; } } + merged_val = bbr->rc_pacer_started; + merged_val <<= 32; + merged_val |= bbr->r_ctl.rc_last_delay_val; bbr_log_pacing_delay_calc(bbr, inp->inp_hpts_calls, - bbr->r_ctl.rc_agg_early, cts, 3, 0, + bbr->r_ctl.rc_agg_early, cts, delay_calc, merged_val, bbr->r_agg_early_set, 3); + bbr->r_ctl.rc_last_delay_val = 0; BBR_STAT_INC(bbr_early); delay_calc = 0; }
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