From 36feebb42f1fb9734c1b99b4afae87d3c8233548 Mon Sep 17 00:00:00 2001 From: Dave Barach Date: Fri, 7 Sep 2018 11:12:27 -0400 Subject: Improve NTP / kernel time change event handling clib_time_verify_frequency(...) rejects clock frequency changes greater than 1%. vlib_worker_thread_barrier_sync_int (...) continuously checks that the barrier hold-down timer is not unreasonably far in the future. Change-Id: I00ecb4c20e44de5d6a9c1499fa933e3dd834d11a Signed-off-by: Dave Barach --- src/vlib/threads.c | 16 ++++++++++++++-- src/vppinfra/time.c | 20 ++++++++++++++++++++ 2 files changed, 34 insertions(+), 2 deletions(-) (limited to 'src') diff --git a/src/vlib/threads.c b/src/vlib/threads.c index 8e75592c0e2..1972886a78b 100644 --- a/src/vlib/threads.c +++ b/src/vlib/threads.c @@ -1466,9 +1466,21 @@ vlib_worker_thread_barrier_sync_int (vlib_main_t * vm) /* Enforce minimum barrier open time to minimize packet loss */ ASSERT (vm->barrier_no_close_before <= (now + BARRIER_MINIMUM_OPEN_LIMIT)); - while ((now = vlib_time_now (vm)) < vm->barrier_no_close_before) - ; + while (1) + { + now = vlib_time_now (vm); + /* Barrier hold-down timer expired? */ + if (now >= vm->barrier_no_close_before) + break; + if ((vm->barrier_no_close_before - now) + > (2.0 * BARRIER_MINIMUM_OPEN_LIMIT)) + { + clib_warning ("clock change: would have waited for %.4f seconds", + (vm->barrier_no_close_before - now)); + break; + } + } /* Record time of closure */ t_open = now - vm->barrier_epoch; vm->barrier_epoch = now; diff --git a/src/vppinfra/time.c b/src/vppinfra/time.c index e9a764bcd31..d647e670dad 100644 --- a/src/vppinfra/time.c +++ b/src/vppinfra/time.c @@ -197,6 +197,7 @@ clib_time_verify_frequency (clib_time_t * c) f64 dtr = now_reference - c->last_verify_reference_time; f64 dtr_max; u64 dtc = c->last_cpu_time - c->last_verify_cpu_time; + f64 new_clocks_per_second, delta; f64 round_units = 100e5; c->last_verify_cpu_time = c->last_cpu_time; @@ -217,6 +218,25 @@ clib_time_verify_frequency (clib_time_t * c) return; } + /* + * Reject large frequency changes, another consequence of + * system clock changes particularly with old kernels. + */ + new_clocks_per_second = + flt_round_nearest ((f64) dtc / (dtr * round_units)) * round_units; + + delta = new_clocks_per_second - c->clocks_per_second; + if (delta < 0.0) + delta = -delta; + + if (PREDICT_FALSE ((delta / c->clocks_per_second) > .01)) + { + clib_warning ("Rejecting large frequency change of %.2f%%", + (delta / c->clocks_per_second) * 100.0); + c->log2_clocks_per_frequency_verify = c->log2_clocks_per_second; + return; + } + c->clocks_per_second = flt_round_nearest ((f64) dtc / (dtr * round_units)) * round_units; c->seconds_per_clock = 1 / c->clocks_per_second; -- cgit 1.2.3-korg