From 56eccdbaa982a6aff16fbc2a651fd024ecc589a8 Mon Sep 17 00:00:00 2001 From: Benoît Ganne Date: Fri, 20 Aug 2021 09:18:31 +0200 Subject: vlib: add virtual time support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Type: feature Change-Id: Iabd76558e9c72ed8286cfeeb1fbaa4fde4832a90 Signed-off-by: Benoît Ganne --- src/vlib/time.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 84 insertions(+) create mode 100644 src/vlib/time.c (limited to 'src/vlib/time.c') diff --git a/src/vlib/time.c b/src/vlib/time.c new file mode 100644 index 00000000000..cfe45a0643c --- /dev/null +++ b/src/vlib/time.c @@ -0,0 +1,84 @@ +/* + * SPDX-License-Identifier: Apache-2.0 + * Copyright(c) 2021 Cisco Systems, Inc. + */ + +/* Virtual time allows to adjust VPP clock by arbitrary amount of time. + * It is done such that the order of timer expirations is maintained, + * and if a timer expiration callback reschedule another timer, this + * timer will also properly expire in the right order. IOW, the order + * of events is preserved. + * + * When moving time forward, each VPP thread (main and workers) runs an + * instance of the input node 'virtual-time-input' below. This node is + * responsible of advancing its own VPP thread clock to the next timer + * expiration. IOW each thread will move its clock independently one + * timer at a time. This also means that while moving time forward, each + * thread might not have the exact same view of what 'now' means. Once + * the main thread has finished moving its time forward, the worker thread + * barrier will ensure the timer between main and workers is synchronized. + * + * Using an input node in poll-mode has several advantages, including + * preventing 'unix-epoll-input' to sleep (as it will not sleep if at + * least one polling node is active). */ + +#include +#include + +static f64 vlib_time_virtual_stop; + +static uword +vlib_time_virtual_input (vlib_main_t *vm, vlib_node_runtime_t *node, + vlib_frame_t *frame) +{ + const f64 next = vlib_time_get_next_timer (vm); + /* each thread will advance its own time. In case a thread is much faster + * than another, we must make sure it does not run away... */ + if (vlib_time_now (vm) + next > vlib_time_virtual_stop) + vlib_node_set_state (vm, node->node_index, VLIB_NODE_STATE_DISABLED); + else + vlib_time_adjust (vm, next); + return 0; +} + +VLIB_REGISTER_NODE (vlib_time_virtual_input_node) = { + .function = vlib_time_virtual_input, + .type = VLIB_NODE_TYPE_INPUT, + .name = "virtual-time-input", + .state = VLIB_NODE_STATE_DISABLED, +}; + +static clib_error_t * +vlib_time_virtual_adjust_command_fn (vlib_main_t *vm, unformat_input_t *input, + vlib_cli_command_t *cmd) +{ + f64 val; + + if (!unformat (input, "%f", &val)) + return clib_error_create ("unknown input `%U'", format_unformat_error, + input); + + vlib_time_virtual_stop = vlib_time_now (vm) + val; + + foreach_vlib_main () + vlib_node_set_state (this_vlib_main, vlib_time_virtual_input_node.index, + VLIB_NODE_STATE_POLLING); + + vlib_worker_thread_barrier_release (vm); + while ((val = vlib_process_wait_for_event_or_clock (vm, val)) >= 0.001) + ; + /* this barrier sync will resynchronize all the clocks, so even if the main + * thread was faster than some workers, this will make sure the workers will + * disable their virtual-time-input node on their next iteration (as stop + * time is reached). If a worker is too slow, there is a slight chance + * several of its timers expire at the same time at this point. Time will + * tell... */ + vlib_worker_thread_barrier_sync (vm); + return 0; +} + +VLIB_CLI_COMMAND (vlib_time_virtual_command) = { + .path = "set clock adjust", + .short_help = "set clock adjust ", + .function = vlib_time_virtual_adjust_command_fn, +}; -- cgit 1.2.3-korg