diff options
| author | Gabriele Monaco <gmonaco@redhat.com> | 2025-07-28 15:50:19 +0200 |
|---|---|---|
| committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2025-07-28 16:47:34 -0400 |
| commit | d0096c2f9cfcb4ce385698491604610fcc1a53b3 (patch) | |
| tree | 7d816e666ac7d4aff6b968447a715e7218017eeb /Documentation/trace/rv | |
| parent | adcc3bfa8806761ac21aa271f78454113ec6936e (diff) | |
rv: Replace tss and sncid monitors with more complete sts
The tss monitor currently guarantees task switches can happen only while
scheduling, whereas the sncid monitor enforces scheduling occurs with
interrupt disabled.
Replace the monitors with a more comprehensive specification which
implies both but also ensures that:
* each scheduler call disable interrupts to switch
* each task switch happens with interrupts disabled
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Nam Cao <namcao@linutronix.de>
Cc: Tomas Glozar <tglozar@redhat.com>
Cc: Juri Lelli <jlelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/20250728135022.255578-8-gmonaco@redhat.com
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'Documentation/trace/rv')
| -rw-r--r-- | Documentation/trace/rv/monitor_sched.rst | 87 |
1 files changed, 48 insertions, 39 deletions
diff --git a/Documentation/trace/rv/monitor_sched.rst b/Documentation/trace/rv/monitor_sched.rst index 24b2c62a3bc2..6c4c00216c07 100644 --- a/Documentation/trace/rv/monitor_sched.rst +++ b/Documentation/trace/rv/monitor_sched.rst @@ -40,26 +40,6 @@ defined in by Daniel Bristot in [1]. Currently we included the following: -Monitor tss -~~~~~~~~~~~ - -The task switch while scheduling (tss) monitor ensures a task switch happens -only in scheduling context, that is inside a call to `__schedule`:: - - | - | - v - +-----------------+ - | thread | <+ - +-----------------+ | - | | - | schedule_entry | schedule_exit - v | - sched_switch | - +--------------- | - | sched | - +--------------> -+ - Monitor sco ~~~~~~~~~~~ @@ -144,26 +124,55 @@ does not enable preemption:: | scheduling_contex -+ -Monitor sncid -~~~~~~~~~~~~~ - -The schedule not called with interrupt disabled (sncid) monitor ensures -schedule is not called with interrupt disabled:: +Monitor sts +~~~~~~~~~~~ - | - | - v - schedule_entry +--------------+ - schedule_exit | | - +----------------- | can_sched | - | | | - +----------------> | | <+ - +--------------+ | - | | - | irq_disable | irq_enable - v | - | - cant_sched -+ +The schedule implies task switch (sts) monitor ensures a task switch happens +only in scheduling context and up to once, as well as scheduling occurs with +interrupts enabled but no task switch can happen before interrupts are +disabled. When the next task picked for execution is the same as the previously +running one, no real task switch occurs but interrupts are disabled nonetheless:: + + irq_entry | + +----+ | + v | v + +------------+ irq_enable #===================# irq_disable + | | ------------> H H irq_entry + | cant_sched | <------------ H H irq_enable + | | irq_disable H can_sched H --------------+ + +------------+ H H | + H H | + +---------------> H H <-------------+ + | #===================# + | | + schedule_exit | schedule_entry + | v + | +-------------------+ irq_enable + | | scheduling | <---------------+ + | +-------------------+ | + | | | + | | irq_disable +--------+ irq_entry + | v | | --------+ + | +-------------------+ irq_entry | in_irq | | + | | | -----------> | | <-------+ + | | disable_to_switch | +--------+ + | | | --+ + | +-------------------+ | + | | | + | | sched_switch | + | v | + | +-------------------+ | + | | switching | | irq_enable + | +-------------------+ | + | | | + | | irq_enable | + | v | + | +-------------------+ | + +-- | enable_to_exit | <-+ + +-------------------+ + ^ | irq_disable + | | irq_entry + +---------------+ irq_enable References ---------- |