Add a per-cpu monitor as part of the sched model:
* opid: operations with preemption and irq disabled
Monitor to ensure wakeup and need_resched occur with irq and
preemption disabled or in irq handlers.
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
---
Documentation/trace/rv/monitor_sched.rst | 55 +++++++
kernel/trace/rv/Kconfig | 1 +
kernel/trace/rv/Makefile | 1 +
kernel/trace/rv/monitors/nrp/Kconfig | 2 +-
kernel/trace/rv/monitors/opid/Kconfig | 17 +++
kernel/trace/rv/monitors/opid/opid.c | 169 +++++++++++++++++++++
kernel/trace/rv/monitors/opid/opid.h | 104 +++++++++++++
kernel/trace/rv/monitors/opid/opid_trace.h | 15 ++
kernel/trace/rv/rv_trace.h | 1 +
tools/verification/models/sched/opid.dot | 35 +++++
10 files changed, 399 insertions(+), 1 deletion(-)
create mode 100644 kernel/trace/rv/monitors/opid/Kconfig
create mode 100644 kernel/trace/rv/monitors/opid/opid.c
create mode 100644 kernel/trace/rv/monitors/opid/opid.h
create mode 100644 kernel/trace/rv/monitors/opid/opid_trace.h
create mode 100644 tools/verification/models/sched/opid.dot
diff --git a/Documentation/trace/rv/monitor_sched.rst b/Documentation/trace/rv/monitor_sched.rst
index 4cb6590284786..6f796e22dbab6 100644
--- a/Documentation/trace/rv/monitor_sched.rst
+++ b/Documentation/trace/rv/monitor_sched.rst
@@ -366,6 +366,61 @@ after the task got to ``sleeping`` until a ``wakeup``::
| |
+----------------------------+
+Monitor opid
+------------
+
+The operations with preemption and irq disabled (opid) monitor ensures
+operations like ``wakeup`` and ``need_resched`` occur with interrupts and
+preemption disabled or during interrupt context, in such case preemption may
+not be disabled explicitly.
+``need_resched`` can be set by some RCU internals functions, in which case it
+doesn't match a task wakeup and might occur with only interrupts disabled::
+
+ | sched_need_resched
+ | sched_waking
+ | irq_entry
+ | +--------------------+
+ v v |
+ +------------------------------------------------------+
+ +----------- | disabled | <+
+ | +------------------------------------------------------+ |
+ | | ^ |
+ | | preempt_disable sched_need_resched |
+ | preempt_enable | +--------------------+ |
+ | v | v | |
+ | +------------------------------------------------------+ |
+ | | irq_disabled | |
+ | +------------------------------------------------------+ |
+ | | | ^ |
+ | irq_entry | | |
+ | sched_need_resched v | irq_disable |
+ | sched_waking +--------------+ | | |
+ | +----- | | irq_enable | |
+ | | | in_irq | | | |
+ | +----> | | | | |
+ | +--------------+ | | irq_disable
+ | | | | |
+ | irq_enable | irq_enable | | |
+ | v v | |
+ | #======================================================# |
+ | H enabled H |
+ | #======================================================# |
+ | | ^ ^ preempt_enable | |
+ | preempt_disable preempt_enable +--------------------+ |
+ | v | |
+ | +------------------+ | |
+ +----------> | preempt_disabled | -+ |
+ +------------------+ |
+ | |
+ +-------------------------------------------------------+
+
+This monitor is designed to work on ``PREEMPT_RT`` kernels, the special case of
+events occurring in interrupt context is a shortcut to identify valid scenarios
+where the preemption tracepoints might not be visible, during interrupts
+preemption is always disabled. On non- ``PREEMPT_RT`` kernels, the interrupts
+might invoke a softirq to set ``need_resched`` and wake up a task. This is
+another special case that is currently not supported by the monitor.
+
References
----------
diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig
index 2cce1f22892a0..86d4c59ca4966 100644
--- a/kernel/trace/rv/Kconfig
+++ b/kernel/trace/rv/Kconfig
@@ -53,6 +53,7 @@ source "kernel/trace/rv/monitors/sncid/Kconfig"
source "kernel/trace/rv/monitors/sts/Kconfig"
source "kernel/trace/rv/monitors/nrp/Kconfig"
source "kernel/trace/rv/monitors/sssw/Kconfig"
+source "kernel/trace/rv/monitors/opid/Kconfig"
# Add new sched monitors here
source "kernel/trace/rv/monitors/rtapp/Kconfig"
diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile
index 3f517fe639c5a..955d0947122ce 100644
--- a/kernel/trace/rv/Makefile
+++ b/kernel/trace/rv/Makefile
@@ -17,6 +17,7 @@ obj-$(CONFIG_RV_MON_SLEEP) += monitors/sleep/sleep.o
obj-$(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-$(CONFIG_RV_MON_OPID) += monitors/opid/opid.o
# Add new monitors here
obj-$(CONFIG_RV_REACTORS) += rv_reactors.o
obj-$(CONFIG_RV_REACT_PRINTK) += reactor_printk.o
diff --git a/kernel/trace/rv/monitors/nrp/Kconfig b/kernel/trace/rv/monitors/nrp/Kconfig
index f37ff70e8d204..a175c430d351f 100644
--- a/kernel/trace/rv/monitors/nrp/Kconfig
+++ b/kernel/trace/rv/monitors/nrp/Kconfig
@@ -3,7 +3,7 @@
config RV_MON_NRP
depends on RV
depends on RV_MON_SCHED
- default y if !ARCH_ARM64
+ default y if !ARM64
select DA_MON_EVENTS_ID
bool "nrp monitor"
help
diff --git a/kernel/trace/rv/monitors/opid/Kconfig b/kernel/trace/rv/monitors/opid/Kconfig
new file mode 100644
index 0000000000000..23b43d2704153
--- /dev/null
+++ b/kernel/trace/rv/monitors/opid/Kconfig
@@ -0,0 +1,17 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+config RV_MON_OPID
+ depends on RV
+ depends on TRACE_IRQFLAGS
+ depends on TRACE_PREEMPT_TOGGLE
+ depends on RV_MON_SCHED
+ default y if PREEMPT_RT
+ select DA_MON_EVENTS_IMPLICIT
+ bool "opid monitor"
+ help
+ Monitor to ensure operations like wakeup and need resched occur with
+ interrupts and preemption disabled or during IRQs, where preemption
+ may not be disabled explicitly.
+
+ For further information, see:
+ Documentation/trace/rv/monitor_sched.rst
diff --git a/kernel/trace/rv/monitors/opid/opid.c b/kernel/trace/rv/monitors/opid/opid.c
new file mode 100644
index 0000000000000..4f1902f24805c
--- /dev/null
+++ b/kernel/trace/rv/monitors/opid/opid.c
@@ -0,0 +1,169 @@
+// 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>
+#include <rv/da_monitor.h>
+
+#define MODULE_NAME "opid"
+
+#include <trace/events/sched.h>
+#include <trace/events/irq.h>
+#include <trace/events/preemptirq.h>
+#include <rv_trace.h>
+#include <monitors/sched/sched.h>
+
+#include "opid.h"
+
+static struct rv_monitor rv_opid;
+DECLARE_DA_MON_PER_CPU(opid, unsigned char);
+
+#ifdef CONFIG_X86_LOCAL_APIC
+#include <asm/trace/irq_vectors.h>
+
+static void handle_vector_irq_entry(void *data, int vector)
+{
+ da_handle_event_opid(irq_entry_opid);
+}
+
+static void attach_vector_irq(void)
+{
+ rv_attach_trace_probe("opid", local_timer_entry, handle_vector_irq_entry);
+ if (IS_ENABLED(CONFIG_IRQ_WORK))
+ rv_attach_trace_probe("opid", irq_work_entry, handle_vector_irq_entry);
+ if (IS_ENABLED(CONFIG_SMP)) {
+ rv_attach_trace_probe("opid", reschedule_entry, handle_vector_irq_entry);
+ rv_attach_trace_probe("opid", call_function_entry, handle_vector_irq_entry);
+ rv_attach_trace_probe("opid", call_function_single_entry, handle_vector_irq_entry);
+ }
+}
+
+static void detach_vector_irq(void)
+{
+ rv_detach_trace_probe("opid", local_timer_entry, handle_vector_irq_entry);
+ if (IS_ENABLED(CONFIG_IRQ_WORK))
+ rv_detach_trace_probe("opid", irq_work_entry, handle_vector_irq_entry);
+ if (IS_ENABLED(CONFIG_SMP)) {
+ rv_detach_trace_probe("opid", reschedule_entry, handle_vector_irq_entry);
+ rv_detach_trace_probe("opid", call_function_entry, handle_vector_irq_entry);
+ rv_detach_trace_probe("opid", call_function_single_entry, handle_vector_irq_entry);
+ }
+}
+
+#else
+/* We assume irq_entry tracepoints are sufficient on other architectures */
+static void attach_vector_irq(void) { }
+static void detach_vector_irq(void) { }
+#endif
+
+static void handle_irq_disable(void *data, unsigned long ip, unsigned long parent_ip)
+{
+ da_handle_event_opid(irq_disable_opid);
+}
+
+static void handle_irq_enable(void *data, unsigned long ip, unsigned long parent_ip)
+{
+ da_handle_event_opid(irq_enable_opid);
+}
+
+static void handle_irq_entry(void *data, int irq, struct irqaction *action)
+{
+ da_handle_event_opid(irq_entry_opid);
+}
+
+static void handle_preempt_disable(void *data, unsigned long ip, unsigned long parent_ip)
+{
+ da_handle_event_opid(preempt_disable_opid);
+}
+
+static void handle_preempt_enable(void *data, unsigned long ip, unsigned long parent_ip)
+{
+ da_handle_event_opid(preempt_enable_opid);
+}
+
+static void handle_sched_need_resched(void *data, struct task_struct *tsk, int cpu, int tif)
+{
+ /* The monitor's intitial state is not in_irq */
+ if (this_cpu_read(hardirq_context))
+ da_handle_event_opid(sched_need_resched_opid);
+ else
+ da_handle_start_event_opid(sched_need_resched_opid);
+}
+
+static void handle_sched_waking(void *data, struct task_struct *p)
+{
+ /* The monitor's intitial state is not in_irq */
+ if (this_cpu_read(hardirq_context))
+ da_handle_event_opid(sched_waking_opid);
+ else
+ da_handle_start_event_opid(sched_waking_opid);
+}
+
+static int enable_opid(void)
+{
+ int retval;
+
+ retval = da_monitor_init_opid();
+ if (retval)
+ return retval;
+
+ rv_attach_trace_probe("opid", irq_disable, handle_irq_disable);
+ rv_attach_trace_probe("opid", irq_enable, handle_irq_enable);
+ rv_attach_trace_probe("opid", irq_handler_entry, handle_irq_entry);
+ rv_attach_trace_probe("opid", preempt_disable, handle_preempt_disable);
+ rv_attach_trace_probe("opid", preempt_enable, handle_preempt_enable);
+ rv_attach_trace_probe("opid", sched_set_need_resched_tp, handle_sched_need_resched);
+ rv_attach_trace_probe("opid", sched_waking, handle_sched_waking);
+ attach_vector_irq();
+
+ return 0;
+}
+
+static void disable_opid(void)
+{
+ rv_opid.enabled = 0;
+
+ rv_detach_trace_probe("opid", irq_disable, handle_irq_disable);
+ rv_detach_trace_probe("opid", irq_enable, handle_irq_enable);
+ rv_detach_trace_probe("opid", irq_handler_entry, handle_irq_entry);
+ rv_detach_trace_probe("opid", preempt_disable, handle_preempt_disable);
+ rv_detach_trace_probe("opid", preempt_enable, handle_preempt_enable);
+ rv_detach_trace_probe("opid", sched_set_need_resched_tp, handle_sched_need_resched);
+ rv_detach_trace_probe("opid", sched_waking, handle_sched_waking);
+ detach_vector_irq();
+
+ da_monitor_destroy_opid();
+}
+
+/*
+ * This is the monitor register section.
+ */
+static struct rv_monitor rv_opid = {
+ .name = "opid",
+ .description = "operations with preemption and irq disabled.",
+ .enable = enable_opid,
+ .disable = disable_opid,
+ .reset = da_monitor_reset_all_opid,
+ .enabled = 0,
+};
+
+static int __init register_opid(void)
+{
+ rv_register_monitor(&rv_opid, &rv_sched);
+ return 0;
+}
+
+static void __exit unregister_opid(void)
+{
+ rv_unregister_monitor(&rv_opid);
+}
+
+module_init(register_opid);
+module_exit(unregister_opid);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Gabriele Monaco <gmonaco@redhat.com>");
+MODULE_DESCRIPTION("opid: operations with preemption and irq disabled.");
diff --git a/kernel/trace/rv/monitors/opid/opid.h b/kernel/trace/rv/monitors/opid/opid.h
new file mode 100644
index 0000000000000..efdbcda8fff30
--- /dev/null
+++ b/kernel/trace/rv/monitors/opid/opid.h
@@ -0,0 +1,104 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Automatically generated C representation of opid automaton
+ * For further information about this format, see kernel documentation:
+ * Documentation/trace/rv/deterministic_automata.rst
+ */
+
+enum states_opid {
+ disabled_opid = 0,
+ enabled_opid,
+ in_irq_opid,
+ irq_disabled_opid,
+ preempt_disabled_opid,
+ state_max_opid
+};
+
+#define INVALID_STATE state_max_opid
+
+enum events_opid {
+ irq_disable_opid = 0,
+ irq_enable_opid,
+ irq_entry_opid,
+ preempt_disable_opid,
+ preempt_enable_opid,
+ sched_need_resched_opid,
+ sched_waking_opid,
+ event_max_opid
+};
+
+struct automaton_opid {
+ char *state_names[state_max_opid];
+ char *event_names[event_max_opid];
+ unsigned char function[state_max_opid][event_max_opid];
+ unsigned char initial_state;
+ bool final_states[state_max_opid];
+};
+
+static const struct automaton_opid automaton_opid = {
+ .state_names = {
+ "disabled",
+ "enabled",
+ "in_irq",
+ "irq_disabled",
+ "preempt_disabled"
+ },
+ .event_names = {
+ "irq_disable",
+ "irq_enable",
+ "irq_entry",
+ "preempt_disable",
+ "preempt_enable",
+ "sched_need_resched",
+ "sched_waking"
+ },
+ .function = {
+ {
+ INVALID_STATE,
+ preempt_disabled_opid,
+ disabled_opid,
+ INVALID_STATE,
+ irq_disabled_opid,
+ disabled_opid,
+ disabled_opid
+ },
+ {
+ irq_disabled_opid,
+ INVALID_STATE,
+ INVALID_STATE,
+ preempt_disabled_opid,
+ enabled_opid,
+ INVALID_STATE,
+ INVALID_STATE
+ },
+ {
+ INVALID_STATE,
+ enabled_opid,
+ INVALID_STATE,
+ INVALID_STATE,
+ INVALID_STATE,
+ in_irq_opid,
+ in_irq_opid
+ },
+ {
+ INVALID_STATE,
+ enabled_opid,
+ in_irq_opid,
+ disabled_opid,
+ INVALID_STATE,
+ irq_disabled_opid,
+ INVALID_STATE
+ },
+ {
+ disabled_opid,
+ INVALID_STATE,
+ INVALID_STATE,
+ INVALID_STATE,
+ enabled_opid,
+ INVALID_STATE,
+ INVALID_STATE
+ },
+ },
+ .initial_state = disabled_opid,
+ .final_states = { 0, 1, 0, 0, 0 },
+};
diff --git a/kernel/trace/rv/monitors/opid/opid_trace.h b/kernel/trace/rv/monitors/opid/opid_trace.h
new file mode 100644
index 0000000000000..3df6ff955c300
--- /dev/null
+++ b/kernel/trace/rv/monitors/opid/opid_trace.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * Snippet to be included in rv_trace.h
+ */
+
+#ifdef CONFIG_RV_MON_OPID
+DEFINE_EVENT(event_da_monitor, event_opid,
+ TP_PROTO(char *state, char *event, char *next_state, bool final_state),
+ TP_ARGS(state, event, next_state, final_state));
+
+DEFINE_EVENT(error_da_monitor, error_opid,
+ TP_PROTO(char *state, char *event),
+ TP_ARGS(state, event));
+#endif /* CONFIG_RV_MON_OPID */
diff --git a/kernel/trace/rv/rv_trace.h b/kernel/trace/rv/rv_trace.h
index b5cb1d1807fd2..c2e841a080df6 100644
--- a/kernel/trace/rv/rv_trace.h
+++ b/kernel/trace/rv/rv_trace.h
@@ -63,6 +63,7 @@ DECLARE_EVENT_CLASS(error_da_monitor,
#include <monitors/snep/snep_trace.h>
#include <monitors/sncid/sncid_trace.h>
#include <monitors/sts/sts_trace.h>
+#include <monitors/opid/opid_trace.h>
// Add new monitors based on CONFIG_DA_MON_EVENTS_IMPLICIT here
#endif /* CONFIG_DA_MON_EVENTS_IMPLICIT */
diff --git a/tools/verification/models/sched/opid.dot b/tools/verification/models/sched/opid.dot
new file mode 100644
index 0000000000000..2d5e1df3405f2
--- /dev/null
+++ b/tools/verification/models/sched/opid.dot
@@ -0,0 +1,35 @@
+digraph state_automaton {
+ center = true;
+ size = "7,11";
+ {node [shape = plaintext, style=invis, label=""] "__init_disabled"};
+ {node [shape = circle] "disabled"};
+ {node [shape = doublecircle] "enabled"};
+ {node [shape = circle] "enabled"};
+ {node [shape = circle] "in_irq"};
+ {node [shape = circle] "irq_disabled"};
+ {node [shape = circle] "preempt_disabled"};
+ "__init_disabled" -> "disabled";
+ "disabled" [label = "disabled"];
+ "disabled" -> "disabled" [ label = "sched_need_resched\nsched_waking\nirq_entry" ];
+ "disabled" -> "irq_disabled" [ label = "preempt_enable" ];
+ "disabled" -> "preempt_disabled" [ label = "irq_enable" ];
+ "enabled" [label = "enabled", color = green3];
+ "enabled" -> "enabled" [ label = "preempt_enable" ];
+ "enabled" -> "irq_disabled" [ label = "irq_disable" ];
+ "enabled" -> "preempt_disabled" [ label = "preempt_disable" ];
+ "in_irq" [label = "in_irq"];
+ "in_irq" -> "enabled" [ label = "irq_enable" ];
+ "in_irq" -> "in_irq" [ label = "sched_need_resched\nsched_waking" ];
+ "irq_disabled" [label = "irq_disabled"];
+ "irq_disabled" -> "disabled" [ label = "preempt_disable" ];
+ "irq_disabled" -> "enabled" [ label = "irq_enable" ];
+ "irq_disabled" -> "in_irq" [ label = "irq_entry" ];
+ "irq_disabled" -> "irq_disabled" [ label = "sched_need_resched" ];
+ "preempt_disabled" [label = "preempt_disabled"];
+ "preempt_disabled" -> "disabled" [ label = "irq_disable" ];
+ "preempt_disabled" -> "enabled" [ label = "preempt_enable" ];
+ { rank = min ;
+ "__init_disabled";
+ "disabled";
+ }
+}
--
2.50.1On Tue, Jul 15, 2025 at 09:14:34AM +0200, Gabriele Monaco wrote: > diff --git a/kernel/trace/rv/monitors/nrp/Kconfig b/kernel/trace/rv/monitors/nrp/Kconfig > index f37ff70e8d204..a175c430d351f 100644 > --- a/kernel/trace/rv/monitors/nrp/Kconfig > +++ b/kernel/trace/rv/monitors/nrp/Kconfig > @@ -3,7 +3,7 @@ > config RV_MON_NRP > depends on RV > depends on RV_MON_SCHED > - default y if !ARCH_ARM64 > + default y if !ARM64 I think this is not supposed to be in this patch? It has nothing to do with the opid monitor. > select DA_MON_EVENTS_ID > bool "nrp monitor" > help > diff --git a/kernel/trace/rv/monitors/opid/Kconfig b/kernel/trace/rv/monitors/opid/Kconfig > new file mode 100644 > index 0000000000000..23b43d2704153 > --- /dev/null > +++ b/kernel/trace/rv/monitors/opid/Kconfig > @@ -0,0 +1,17 @@ > +# SPDX-License-Identifier: GPL-2.0-only > +# > +config RV_MON_OPID > + depends on RV > + depends on TRACE_IRQFLAGS > + depends on TRACE_PREEMPT_TOGGLE > + depends on RV_MON_SCHED > + default y if PREEMPT_RT > + select DA_MON_EVENTS_IMPLICIT Shouldn't we add "depends on PREEMPT_RT"? I tried this monitor on non-RT x86 kernel, and got some errors. That could confuse people. And the monitor reports some errors on riscv64 with PREEMPT_RT=y: root@riscv:~/rv-tests# uname -a Linux riscv 6.16.0-rc6-00054-g7590637d9ca2 #87 SMP PREEMPT_RT Wed Jul 16 11:26:00 CEST 2025 riscv64 GNU/Linux root@riscv:~/rv-tests# stress-ng --cpu-sched -1 stress-ng: info: [452] defaulting to a 1 day run per stressor stress-ng: info: [452] dispatching hogs: 4 cpu-sched [ 614.390462] rv: monitor opid does not allow event irq_entry on state in_irq Best regards, Nam
On Wed, 2025-07-16 at 11:38 +0200, Nam Cao wrote: > And the monitor reports some errors on riscv64 with PREEMPT_RT=y: > > root@riscv:~/rv-tests# uname -a > Linux riscv 6.16.0-rc6-00054-g7590637d9ca2 #87 SMP PREEMPT_RT Wed Jul > 16 11:26:00 CEST 2025 riscv64 GNU/Linux > root@riscv:~/rv-tests# stress-ng --cpu-sched -1 > stress-ng: info: [452] defaulting to a 1 day run per stressor > stress-ng: info: [452] dispatching hogs: 4 cpu-sched > [ 614.390462] rv: monitor opid does not allow event irq_entry on > state in_irq Finally managed to bootstrap a riscv VM, that is an error I thought I'd fixed and I'm genuinely surprised I didn't notice on other architectures. Thanks again for catching it though! Gabriele
On Wed, 2025-07-16 at 11:38 +0200, Nam Cao wrote: > On Tue, Jul 15, 2025 at 09:14:34AM +0200, Gabriele Monaco wrote: > > diff --git a/kernel/trace/rv/monitors/nrp/Kconfig > > b/kernel/trace/rv/monitors/nrp/Kconfig > > index f37ff70e8d204..a175c430d351f 100644 > > --- a/kernel/trace/rv/monitors/nrp/Kconfig > > +++ b/kernel/trace/rv/monitors/nrp/Kconfig > > @@ -3,7 +3,7 @@ > > config RV_MON_NRP > > depends on RV > > depends on RV_MON_SCHED > > - default y if !ARCH_ARM64 > > + default y if !ARM64 > > I think this is not supposed to be in this patch? It has nothing to > do with > the opid monitor. Damn, fixed up the wrong patch, will move it to the other one.. > > > select DA_MON_EVENTS_ID > > bool "nrp monitor" > > help > > diff --git a/kernel/trace/rv/monitors/opid/Kconfig > > b/kernel/trace/rv/monitors/opid/Kconfig > > new file mode 100644 > > index 0000000000000..23b43d2704153 > > --- /dev/null > > +++ b/kernel/trace/rv/monitors/opid/Kconfig > > @@ -0,0 +1,17 @@ > > +# SPDX-License-Identifier: GPL-2.0-only > > +# > > +config RV_MON_OPID > > + depends on RV > > + depends on TRACE_IRQFLAGS > > + depends on TRACE_PREEMPT_TOGGLE > > + depends on RV_MON_SCHED > > + default y if PREEMPT_RT > > + select DA_MON_EVENTS_IMPLICIT > > Shouldn't we add "depends on PREEMPT_RT"? I tried this monitor on > non-RT x86 kernel, and got some errors. That could confuse people. Mmh, my rationale was that it reports errors on non PREEMPT_RT, but it does build. If someone wants to try it out there, they are free to do it. We are just not supporting it officially. The monitor might start working in the future also on non RT kernels, or at least if someone wants to try whether it's the case, they can do it easily. Same idea for the ARM64 thing above. But I should definitely mention this explicitly in the Kconfig entry not to confuse people.. > > And the monitor reports some errors on riscv64 with PREEMPT_RT=y: > > root@riscv:~/rv-tests# uname -a > Linux riscv 6.16.0-rc6-00054-g7590637d9ca2 #87 SMP PREEMPT_RT Wed Jul > 16 11:26:00 CEST 2025 riscv64 GNU/Linux > root@riscv:~/rv-tests# stress-ng --cpu-sched -1 > stress-ng: info: [452] defaulting to a 1 day run per stressor > stress-ng: info: [452] dispatching hogs: 4 cpu-sched > [ 614.390462] rv: monitor opid does not allow event irq_entry on > state in_irq > Mmh riscv.. I haven't tested it there, guess I need to start keeping a VM somewhere. Thanks, Gabriele
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