Add a sample monitor to showcase hybrid/timed automata. The stall monitor identifies tasks stalled for longer than a threshold and reacts when that happens.
Signed-off-by: Gabriele Monaco <gmon...@redhat.com> --- Documentation/tools/rv/rv-mon-stall.rst | 44 +++++++ Documentation/trace/rv/monitor_stall.rst | 43 +++++++ kernel/trace/rv/Kconfig | 1 + kernel/trace/rv/Makefile | 1 + kernel/trace/rv/monitors/stall/Kconfig | 9 ++ kernel/trace/rv/monitors/stall/stall.c | 116 +++++++++++++++++++ kernel/trace/rv/monitors/stall/stall.h | 64 ++++++++++ kernel/trace/rv/monitors/stall/stall_trace.h | 19 +++ kernel/trace/rv/rv_trace.h | 1 + tools/verification/models/stall.dot | 20 ++++ 10 files changed, 318 insertions(+) create mode 100644 Documentation/tools/rv/rv-mon-stall.rst create mode 100644 Documentation/trace/rv/monitor_stall.rst create mode 100644 kernel/trace/rv/monitors/stall/Kconfig create mode 100644 kernel/trace/rv/monitors/stall/stall.c create mode 100644 kernel/trace/rv/monitors/stall/stall.h create mode 100644 kernel/trace/rv/monitors/stall/stall_trace.h create mode 100644 tools/verification/models/stall.dot diff --git a/Documentation/tools/rv/rv-mon-stall.rst b/Documentation/tools/rv/rv-mon-stall.rst new file mode 100644 index 000000000000..c79d7c2e4dd4 --- /dev/null +++ b/Documentation/tools/rv/rv-mon-stall.rst @@ -0,0 +1,44 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============ +rv-mon-stall +============ +-------------------- +Stalled task monitor +-------------------- + +:Manual section: 1 + +SYNOPSIS +======== + +**rv mon stall** [*OPTIONS*] + +DESCRIPTION +=========== + +The stalled task (**stall**) monitor is a sample per-task timed monitor that +checks if tasks are scheduled within a defined threshold after they are ready. + +See kernel documentation for further information about this monitor: +<https://docs.kernel.org/trace/rv/monitor_stall.html> + +OPTIONS +======= + +.. include:: common_ikm.rst + +SEE ALSO +======== + +**rv**\(1), **rv-mon**\(1) + +Linux kernel *RV* documentation: +<https://www.kernel.org/doc/html/latest/trace/rv/index.html> + +AUTHOR +====== + +Written by Gabriele Monaco <gmon...@redhat.com> + +.. include:: common_appendix.rst diff --git a/Documentation/trace/rv/monitor_stall.rst b/Documentation/trace/rv/monitor_stall.rst new file mode 100644 index 000000000000..e4d9b050a32f --- /dev/null +++ b/Documentation/trace/rv/monitor_stall.rst @@ -0,0 +1,43 @@ +Monitor stall +============= + +- Name: stall - wakeup in preemptive +- Type: per-task hybrid automaton +- Author: Gabriele Monaco <gmon...@redhat.com> + +Description +----------- + +The stalled task (stall) monitor is a sample per-task timed monitor that checks +if tasks are scheduled within a defined threshold after they are ready:: + + | + | + v + #==================================# + H dequeued H <+ + #==================================# | + | | + | sched_wakeup;reset(clk) | + v | + +----------------------------------+ | + | enqueued | | + | clk < threshold_jiffies | | sched_switch_wait + +----------------------------------+ | + | | + | sched_switch_in | + sched_switch_in v | + sched_wakeup +----------------------------------+ | + +------------------ | | | + | | running | | + +-----------------> | | -+ + +----------------------------------+ + + +The threshold can be configured as a parameter by either booting with the +``stall.threshold_jiffies=<new value>`` argument or writing a new value to +``/sys/module/stall/parameters/threshold_jiffies``. + +Specification +------------- +Grapviz Dot file in tools/verification/models/stall.dot diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig index 4ad392dfc57f..720fbe4935f8 100644 --- a/kernel/trace/rv/Kconfig +++ b/kernel/trace/rv/Kconfig @@ -78,6 +78,7 @@ source "kernel/trace/rv/monitors/pagefault/Kconfig" source "kernel/trace/rv/monitors/sleep/Kconfig" # Add new rtapp monitors here +source "kernel/trace/rv/monitors/stall/Kconfig" # Add new monitors here config RV_REACTORS diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile index 750e4ad6fa0f..51c95e2d2da6 100644 --- a/kernel/trace/rv/Makefile +++ b/kernel/trace/rv/Makefile @@ -17,6 +17,7 @@ obj-$(CONFIG_RV_MON_STS) += monitors/sts/sts.o obj-$(CONFIG_RV_MON_NRP) += monitors/nrp/nrp.o obj-$(CONFIG_RV_MON_SSSW) += monitors/sssw/sssw.o obj-$(CONFIG_RV_MON_OPID) += monitors/opid/opid.o +obj-$(CONFIG_RV_MON_STALL) += monitors/stall/stall.o # Add new monitors here obj-$(CONFIG_RV_REACTORS) += rv_reactors.o obj-$(CONFIG_RV_REACT_PRINTK) += reactor_printk.o diff --git a/kernel/trace/rv/monitors/stall/Kconfig b/kernel/trace/rv/monitors/stall/Kconfig new file mode 100644 index 000000000000..b19ba970c8af --- /dev/null +++ b/kernel/trace/rv/monitors/stall/Kconfig @@ -0,0 +1,9 @@ +# SPDX-License-Identifier: GPL-2.0-only +# +config RV_MON_STALL + depends on RV + # XXX: add dependencies if there + select HA_MON_EVENTS_ID + bool "stall monitor" + help + auto-generated diff --git a/kernel/trace/rv/monitors/stall/stall.c b/kernel/trace/rv/monitors/stall/stall.c new file mode 100644 index 000000000000..c98ad9838146 --- /dev/null +++ b/kernel/trace/rv/monitors/stall/stall.c @@ -0,0 +1,116 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/ftrace.h> +#include <linux/tracepoint.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/rv.h> +#include <rv/instrumentation.h> + +#define MODULE_NAME "stall" + +#include <trace/events/sched.h> +#include <rv_trace.h> + +#define RV_MON_TYPE RV_MON_PER_TASK +#include "stall.h" +#include <rv/ha_monitor.h> + +static u64 threshold_jiffies = 1000; +module_param(threshold_jiffies, ullong, 0644); + +static u64 ha_get_env(struct ha_monitor *ha_mon, enum envs_stall env) +{ + if (env == clk_stall) + return ha_get_clk_jiffy(ha_mon, env); + return ENV_INVALID_VALUE; +} + +static void ha_reset_env(struct ha_monitor *ha_mon, enum envs_stall env) +{ + if (env == clk_stall) + ha_reset_clk_jiffy(ha_mon, env); +} + +static bool ha_verify_constraint(struct ha_monitor *ha_mon, + enum states curr_state, enum events event, + enum states next_state) +{ + bool res = true; + + if (curr_state == dequeued_stall && event == sched_wakeup_stall) + ha_reset_env(ha_mon, clk_stall); + + if (next_state == curr_state || !res) + return res; + if (next_state == enqueued_stall) + ha_start_timer_jiffy(ha_mon, clk_stall, threshold_jiffies); + else if (curr_state == enqueued_stall) + res = !ha_cancel_timer(ha_mon); + return res; +} + +static void handle_sched_switch(void *data, bool preempt, + struct task_struct *prev, + struct task_struct *next, + unsigned int prev_state) +{ + if (!preempt && prev_state != TASK_RUNNING) + da_handle_start_event(prev, sched_switch_wait_stall); + da_handle_event(next, sched_switch_in_stall); +} + +static void handle_sched_wakeup(void *data, struct task_struct *p) +{ + da_handle_event(p, sched_wakeup_stall); +} + +static int enable_stall(void) +{ + int retval; + + retval = da_monitor_init(); + if (retval) + return retval; + + rv_attach_trace_probe("stall", sched_switch, handle_sched_switch); + rv_attach_trace_probe("stall", sched_wakeup, handle_sched_wakeup); + + return 0; +} + +static void disable_stall(void) +{ + rv_stall.enabled = 0; + + rv_detach_trace_probe("stall", sched_switch, handle_sched_switch); + rv_detach_trace_probe("stall", sched_wakeup, handle_sched_wakeup); + + da_monitor_destroy(); +} + +static struct rv_monitor rv_stall = { + .name = "stall", + .description = "identify tasks stalled for longer than a threshold.", + .enable = enable_stall, + .disable = disable_stall, + .reset = da_monitor_reset_all, + .enabled = 0, +}; + +static int __init register_stall(void) +{ + return rv_register_monitor(&rv_stall, NULL); +} + +static void __exit unregister_stall(void) +{ + rv_unregister_monitor(&rv_stall); +} + +module_init(register_stall); +module_exit(unregister_stall); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Gabriele Monaco <gmon...@redhat.com>"); +MODULE_DESCRIPTION("stall: identify tasks stalled for longer than a threshold."); diff --git a/kernel/trace/rv/monitors/stall/stall.h b/kernel/trace/rv/monitors/stall/stall.h new file mode 100644 index 000000000000..89b32c97c455 --- /dev/null +++ b/kernel/trace/rv/monitors/stall/stall.h @@ -0,0 +1,64 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Automatically generated C representation of stall automaton + * For further information about this format, see kernel documentation: + * Documentation/trace/rv/deterministic_automata.rst + */ + +#define MONITOR_NAME stall + +enum states_stall { + dequeued_stall = 0, + enqueued_stall, + running_stall, + state_max_stall +}; + +#define INVALID_STATE state_max_stall + +enum events_stall { + sched_switch_in_stall = 0, + sched_switch_wait_stall, + sched_wakeup_stall, + event_max_stall +}; + +enum envs_stall { + clk_stall = 0, + env_max_stall, + env_max_stored_stall = env_max_stall +}; + +_Static_assert(env_max_stored_stall <= MAX_HA_ENV_LEN, "Not enough slots"); + +struct automaton_stall { + char *state_names[state_max_stall]; + char *event_names[event_max_stall]; + char *env_names[env_max_stall]; + unsigned char function[state_max_stall][event_max_stall]; + unsigned char initial_state; + bool final_states[state_max_stall]; +}; + +static const struct automaton_stall automaton_stall = { + .state_names = { + "dequeued", + "enqueued", + "running" + }, + .event_names = { + "sched_switch_in", + "sched_switch_wait", + "sched_wakeup" + }, + .env_names = { + "clk" + }, + .function = { + { INVALID_STATE, INVALID_STATE, enqueued_stall }, + { running_stall, INVALID_STATE, INVALID_STATE }, + { running_stall, dequeued_stall, running_stall }, + }, + .initial_state = dequeued_stall, + .final_states = { 1, 0, 0 }, +}; diff --git a/kernel/trace/rv/monitors/stall/stall_trace.h b/kernel/trace/rv/monitors/stall/stall_trace.h new file mode 100644 index 000000000000..6a7cc1b1d040 --- /dev/null +++ b/kernel/trace/rv/monitors/stall/stall_trace.h @@ -0,0 +1,19 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +/* + * Snippet to be included in rv_trace.h + */ + +#ifdef CONFIG_RV_MON_STALL +DEFINE_EVENT(event_da_monitor_id, event_stall, + TP_PROTO(int id, char *state, char *event, char *next_state, bool final_state), + TP_ARGS(id, state, event, next_state, final_state)); + +DEFINE_EVENT(error_da_monitor_id, error_stall, + TP_PROTO(int id, char *state, char *event), + TP_ARGS(id, state, event)); + +DEFINE_EVENT(error_env_da_monitor_id, error_env_stall, + TP_PROTO(int id, char *state, char *event, char *env), + TP_ARGS(id, state, event, env)); +#endif /* CONFIG_RV_MON_STALL */ diff --git a/kernel/trace/rv/rv_trace.h b/kernel/trace/rv/rv_trace.h index dbb0cbbe15ca..3d9a4c70f523 100644 --- a/kernel/trace/rv/rv_trace.h +++ b/kernel/trace/rv/rv_trace.h @@ -187,6 +187,7 @@ DECLARE_EVENT_CLASS(error_env_da_monitor_id, __entry->env) ); +#include <monitors/stall/stall_trace.h> // Add new monitors based on CONFIG_HA_MON_EVENTS_ID here #endif diff --git a/tools/verification/models/stall.dot b/tools/verification/models/stall.dot new file mode 100644 index 000000000000..98e3ae47e104 --- /dev/null +++ b/tools/verification/models/stall.dot @@ -0,0 +1,20 @@ +digraph state_automaton { + center = true; + size = "7,11"; + {node [shape = circle] "enqueued"}; + {node [shape = plaintext, style=invis, label=""] "__init_dequeued"}; + {node [shape = doublecircle] "dequeued"}; + {node [shape = circle] "running"}; + "__init_dequeued" -> "dequeued"; + "enqueued" [label = "enqueued\nclk < threshold_jiffies"]; + "running" [label = "running"]; + "dequeued" [label = "dequeued", color = green3]; + "running" -> "running" [ label = "sched_switch_in\nsched_wakeup" ]; + "enqueued" -> "running" [ label = "sched_switch_in" ]; + "running" -> "dequeued" [ label = "sched_switch_wait" ]; + "dequeued" -> "enqueued" [ label = "sched_wakeup;reset(clk)" ]; + { rank = min ; + "__init_dequeued"; + "dequeued"; + } +} -- 2.50.1
