diff options
Diffstat (limited to 'src/vlib')
| -rw-r--r-- | src/vlib/main.h | 9 | ||||
| -rw-r--r-- | src/vlib/threads.c | 313 | ||||
| -rw-r--r-- | src/vlib/threads.h | 29 |
3 files changed, 340 insertions, 11 deletions
diff --git a/src/vlib/main.h b/src/vlib/main.h index 4c0cde3ff45..fb67334e4e2 100644 --- a/src/vlib/main.h +++ b/src/vlib/main.h @@ -199,6 +199,15 @@ typedef struct vlib_main_t */ int need_vlib_worker_thread_node_runtime_update; + /* + * Barrier epoch - Set to current time, each time barrier_sync or + * barrier_release is called with zero recursion. + */ + f64 barrier_epoch; + + /* Earliest barrier can be closed again */ + f64 barrier_no_close_before; + } vlib_main_t; /* Global main structure. */ diff --git a/src/vlib/threads.c b/src/vlib/threads.c index 6cd325b3e2c..2d9ce84a7cb 100644 --- a/src/vlib/threads.c +++ b/src/vlib/threads.c @@ -35,6 +35,222 @@ vl (void *p) vlib_worker_thread_t *vlib_worker_threads; vlib_thread_main_t vlib_thread_main; +/* + * Barrier tracing can be enabled on a normal build to collect information + * on barrier use, including timings and call stacks. Deliberately not + * keyed off CLIB_DEBUG, because that can add significant overhead which + * imapacts observed timings. + */ + +#ifdef BARRIER_TRACING + /* + * Output of barrier tracing can be to syslog or elog as suits + */ +#ifdef BARRIER_TRACING_ELOG +static u32 +elog_id_for_msg_name (const char *msg_name) +{ + uword *p, r; + static uword *h; + u8 *name_copy; + + if (!h) + h = hash_create_string (0, sizeof (uword)); + + p = hash_get_mem (h, msg_name); + if (p) + return p[0]; + r = elog_string (&vlib_global_main.elog_main, "%s", msg_name); + + name_copy = format (0, "%s%c", msg_name, 0); + + hash_set_mem (h, name_copy, r); + + return r; +} + + /* + * elog Barrier trace functions, which are nulled out if BARRIER_TRACING isn't + * defined + */ + +static inline void +barrier_trace_sync (f64 t_entry, f64 t_open, f64 t_closed) +{ + /* *INDENT-OFF* */ + ELOG_TYPE_DECLARE (e) = + { + .format = "barrier <%d#%s(O:%dus:%dus)(%dus)", + .format_args = "i4T4i4i4i4", + }; + /* *INDENT-ON* */ + struct + { + u32 count, caller, t_entry, t_open, t_closed; + } *ed = 0; + + ed = ELOG_DATA (&vlib_global_main.elog_main, e); + ed->count = (int) vlib_worker_threads[0].barrier_sync_count; + ed->caller = elog_id_for_msg_name (vlib_worker_threads[0].barrier_caller); + ed->t_entry = (int) (1000000.0 * t_entry); + ed->t_open = (int) (1000000.0 * t_open); + ed->t_closed = (int) (1000000.0 * t_closed); +} + +static inline void +barrier_trace_sync_rec (f64 t_entry) +{ + /* *INDENT-OFF* */ + ELOG_TYPE_DECLARE (e) = + { + .format = "barrier <%d(%dus)%s", + .format_args = "i4i4T4", + }; + /* *INDENT-ON* */ + struct + { + u32 depth, t_entry, caller; + } *ed = 0; + + ed = ELOG_DATA (&vlib_global_main.elog_main, e); + ed->depth = (int) vlib_worker_threads[0].recursion_level - 1; + ed->t_entry = (int) (1000000.0 * t_entry); + ed->caller = elog_id_for_msg_name (vlib_worker_threads[0].barrier_caller); +} + +static inline void +barrier_trace_release_rec (f64 t_entry) +{ + /* *INDENT-OFF* */ + ELOG_TYPE_DECLARE (e) = + { + .format = "barrier (%dus)%d>", + .format_args = "i4i4", + }; + /* *INDENT-ON* */ + struct + { + u32 t_entry, depth; + } *ed = 0; + + ed = ELOG_DATA (&vlib_global_main.elog_main, e); + ed->t_entry = (int) (1000000.0 * t_entry); + ed->depth = (int) vlib_worker_threads[0].recursion_level; +} + +static inline void +barrier_trace_release (f64 t_entry, f64 t_closed_total, f64 t_update_main) +{ + /* *INDENT-OFF* */ + ELOG_TYPE_DECLARE (e) = + { + .format = "barrier (%dus){%d}(C:%dus)#%d>", + .format_args = "i4i4i4i4", + }; + /* *INDENT-ON* */ + struct + { + u32 t_entry, t_update_main, t_closed_total, count; + } *ed = 0; + + ed = ELOG_DATA (&vlib_global_main.elog_main, e); + ed->t_entry = (int) (1000000.0 * t_entry); + ed->t_update_main = (int) (1000000.0 * t_update_main); + ed->t_closed_total = (int) (1000000.0 * t_closed_total); + ed->count = (int) vlib_worker_threads[0].barrier_sync_count; + + /* Reset context for next trace */ + vlib_worker_threads[0].barrier_context = NULL; +} +#else +char barrier_trace[65536]; +char *btp = barrier_trace; + + /* + * syslog Barrier trace functions, which are nulled out if BARRIER_TRACING + * isn't defined + */ + + +static inline void +barrier_trace_sync (f64 t_entry, f64 t_open, f64 t_closed) +{ + btp += sprintf (btp, "<%u#%s", + (unsigned int) vlib_worker_threads[0].barrier_sync_count, + vlib_worker_threads[0].barrier_caller); + + if (vlib_worker_threads[0].barrier_context) + { + btp += sprintf (btp, "[%s]", vlib_worker_threads[0].barrier_context); + + } + + btp += sprintf (btp, "(O:%dus:%dus)(%dus):", + (int) (1000000.0 * t_entry), + (int) (1000000.0 * t_open), (int) (1000000.0 * t_closed)); + +} + +static inline void +barrier_trace_sync_rec (f64 t_entry) +{ + btp += sprintf (btp, "<%u(%dus)%s:", + (int) vlib_worker_threads[0].recursion_level - 1, + (int) (1000000.0 * t_entry), + vlib_worker_threads[0].barrier_caller); +} + +static inline void +barrier_trace_release_rec (f64 t_entry) +{ + btp += sprintf (btp, ":(%dus)%u>", (int) (1000000.0 * t_entry), + (int) vlib_worker_threads[0].recursion_level); +} + +static inline void +barrier_trace_release (f64 t_entry, f64 t_closed_total, f64 t_update_main) +{ + + btp += sprintf (btp, ":(%dus)", (int) (1000000.0 * t_entry)); + if (t_update_main > 0) + { + btp += sprintf (btp, "{%dus}", (int) (1000000.0 * t_update_main)); + } + + btp += sprintf (btp, "(C:%dus)#%u>", + (int) (1000000.0 * t_closed_total), + (int) vlib_worker_threads[0].barrier_sync_count); + + /* Dump buffer to syslog, and reset for next trace */ + fformat (stderr, "BTRC %s\n", barrier_trace); + btp = barrier_trace; + vlib_worker_threads[0].barrier_context = NULL; +} +#endif +#else + + /* Null functions for default case where barrier tracing isn't used */ +static inline void +barrier_trace_sync (f64 t_entry, f64 t_open, f64 t_closed) +{ +} + +static inline void +barrier_trace_sync_rec (f64 t_entry) +{ +} + +static inline void +barrier_trace_release_rec (f64 t_entry) +{ +} + +static inline void +barrier_trace_release (f64 t_entry, f64 t_closed_total, f64 t_update_main) +{ +} +#endif + uword os_get_nthreads (void) { @@ -558,6 +774,10 @@ start_workers (vlib_main_t * vm) *vlib_worker_threads->node_reforks_required = 0; vm->need_vlib_worker_thread_node_runtime_update = 0; + /* init timing */ + vm->barrier_epoch = 0; + vm->barrier_no_close_before = 0; + worker_thread_index = 1; for (i = 0; i < vec_len (tm->registrations); i++) @@ -790,6 +1010,7 @@ start_workers (vlib_main_t * vm) VLIB_MAIN_LOOP_ENTER_FUNCTION (start_workers); + static inline void worker_thread_node_runtime_update_internal (void) { @@ -993,7 +1214,6 @@ vlib_worker_thread_node_refork (void) nm_clone->processes = vec_dup (nm->processes); } - void vlib_worker_thread_node_runtime_update (void) { @@ -1192,10 +1412,29 @@ vlib_worker_thread_fork_fixup (vlib_fork_fixup_t which) vlib_worker_thread_barrier_release (vm); } + /* + * Enforce minimum open time to minimize packet loss due to Rx overflow, + * based on a test based heuristic that barrier should be open for at least + * 3 time as long as it is closed (with an upper bound of 1ms because by that + * point it is probably too late to make a difference) + */ + +#ifndef BARRIER_MINIMUM_OPEN_LIMIT +#define BARRIER_MINIMUM_OPEN_LIMIT 0.001 +#endif + +#ifndef BARRIER_MINIMUM_OPEN_FACTOR +#define BARRIER_MINIMUM_OPEN_FACTOR 3 +#endif + void -vlib_worker_thread_barrier_sync (vlib_main_t * vm) +vlib_worker_thread_barrier_sync_int (vlib_main_t * vm) { f64 deadline; + f64 now; + f64 t_entry; + f64 t_open; + f64 t_closed; u32 count; if (vec_len (vlib_mains) < 2) @@ -1205,29 +1444,55 @@ vlib_worker_thread_barrier_sync (vlib_main_t * vm) count = vec_len (vlib_mains) - 1; + /* Record entry relative to last close */ + now = vlib_time_now (vm); + t_entry = now - vm->barrier_epoch; + /* Tolerate recursive calls */ if (++vlib_worker_threads[0].recursion_level > 1) - return; + { + barrier_trace_sync_rec (t_entry); + return; + } vlib_worker_threads[0].barrier_sync_count++; - deadline = vlib_time_now (vm) + BARRIER_SYNC_TIMEOUT; + /* 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) + ; + + /* Record time of closure */ + t_open = now - vm->barrier_epoch; + vm->barrier_epoch = now; + + deadline = now + BARRIER_SYNC_TIMEOUT; *vlib_worker_threads->wait_at_barrier = 1; while (*vlib_worker_threads->workers_at_barrier != count) { - if (vlib_time_now (vm) > deadline) + if ((now = vlib_time_now (vm)) > deadline) { fformat (stderr, "%s: worker thread deadlock\n", __FUNCTION__); os_panic (); } } + + t_closed = now - vm->barrier_epoch; + + barrier_trace_sync (t_entry, t_open, t_closed); + } void vlib_worker_thread_barrier_release (vlib_main_t * vm) { f64 deadline; + f64 now; + f64 minimum_open; + f64 t_entry; + f64 t_closed_total; + f64 t_update_main = 0.0; int refork_needed = 0; if (vec_len (vlib_mains) < 2) @@ -1235,8 +1500,15 @@ vlib_worker_thread_barrier_release (vlib_main_t * vm) ASSERT (vlib_get_thread_index () == 0); + + now = vlib_time_now (vm); + t_entry = now - vm->barrier_epoch; + if (--vlib_worker_threads[0].recursion_level > 0) - return; + { + barrier_trace_release_rec (t_entry); + return; + } /* Update (all) node runtimes before releasing the barrier, if needed */ if (vm->need_vlib_worker_thread_node_runtime_update) @@ -1249,15 +1521,17 @@ vlib_worker_thread_barrier_release (vlib_main_t * vm) refork_needed = 1; clib_smp_atomic_add (vlib_worker_threads->node_reforks_required, (vec_len (vlib_mains) - 1)); + now = vlib_time_now (vm); + t_update_main = now - vm->barrier_epoch; } - deadline = vlib_time_now (vm) + BARRIER_SYNC_TIMEOUT; + deadline = now + BARRIER_SYNC_TIMEOUT; *vlib_worker_threads->wait_at_barrier = 0; while (*vlib_worker_threads->workers_at_barrier > 0) { - if (vlib_time_now (vm) > deadline) + if ((now = vlib_time_now (vm)) > deadline) { fformat (stderr, "%s: worker thread deadlock\n", __FUNCTION__); os_panic (); @@ -1267,11 +1541,13 @@ vlib_worker_thread_barrier_release (vlib_main_t * vm) /* Wait for reforks before continuing */ if (refork_needed) { - deadline = vlib_time_now (vm) + BARRIER_SYNC_TIMEOUT; + now = vlib_time_now (vm); + + deadline = now + BARRIER_SYNC_TIMEOUT; while (*vlib_worker_threads->node_reforks_required > 0) { - if (vlib_time_now (vm) > deadline) + if ((now = vlib_time_now (vm)) > deadline) { fformat (stderr, "%s: worker thread refork deadlock\n", __FUNCTION__); @@ -1279,6 +1555,23 @@ vlib_worker_thread_barrier_release (vlib_main_t * vm) } } } + + t_closed_total = now - vm->barrier_epoch; + + minimum_open = t_closed_total * BARRIER_MINIMUM_OPEN_FACTOR; + + if (minimum_open > BARRIER_MINIMUM_OPEN_LIMIT) + { + minimum_open = BARRIER_MINIMUM_OPEN_LIMIT; + } + + vm->barrier_no_close_before = now + minimum_open; + + /* Record barrier epoch (used to enforce minimum open time) */ + vm->barrier_epoch = now; + + barrier_trace_release (t_entry, t_closed_total, t_update_main); + } /* diff --git a/src/vlib/threads.h b/src/vlib/threads.h index c3f1cadee16..72340ee1a37 100644 --- a/src/vlib/threads.h +++ b/src/vlib/threads.h @@ -18,6 +18,22 @@ #include <vlib/main.h> #include <linux/sched.h> +/* + * To enable detailed tracing of barrier usage, including call stacks and + * timings, define BARRIER_TRACING here or in relevant TAGS. If also used + * with CLIB_DEBUG, timing will _not_ be representative of normal code + * execution. + * + */ + +// #define BARRIER_TRACING 1 + +/* + * Two options for barrier tracing output: syslog & elog. + */ + +// #define BARRIER_TRACING_ELOG 1 + extern vlib_main_t **vlib_mains; void vlib_set_thread_name (char *name); @@ -102,6 +118,10 @@ typedef struct vlib_thread_registration_t *registration; u8 *name; u64 barrier_sync_count; +#ifdef BARRIER_TRACING + const char *barrier_caller; + const char *barrier_context; +#endif volatile u32 *node_reforks_required; long lwp; @@ -179,7 +199,14 @@ u32 vlib_frame_queue_main_init (u32 node_index, u32 frame_queue_nelts); #define BARRIER_SYNC_TIMEOUT (1.0) #endif -void vlib_worker_thread_barrier_sync (vlib_main_t * vm); +#ifdef BARRIER_TRACING +#define vlib_worker_thread_barrier_sync(X) {vlib_worker_threads[0].barrier_caller=__FUNCTION__;vlib_worker_thread_barrier_sync_int(X);} +#else +#define vlib_worker_thread_barrier_sync(X) vlib_worker_thread_barrier_sync_int(X) +#endif + + +void vlib_worker_thread_barrier_sync_int (vlib_main_t * vm); void vlib_worker_thread_barrier_release (vlib_main_t * vm); void vlib_worker_thread_node_refork (void); |