[RFC PATCH] Documentation/rv: Explain epoll and aborted sleeps
From: Chao Liu <hidden>
Date: 2026-07-22 04:57:28
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linux-doc, lkml
Subsystem:
documentation, runtime verification (rv), the rest, tracing · Maintainers:
Jonathan Corbet, Steven Rostedt, Gabriele Monaco, Linus Torvalds, Masami Hiramatsu
The rtapp sleep monitor accepts epoll_wait() as a valid sleeping reason, but the prose only discusses clock_nanosleep and futexes. Add epoll_wait to the list of valid sleeping reasons. ABORT_SLEEP represents a task restoring TASK_RUNNING before entering the scheduler, but its meaning is not described. Explain why the aborted sleep attempt is valid. This RFC is based on Nam Cao's pending "rv: rtapp monitor update" v2 series: https://lore.kernel.org/r/cover.1781852967.git.namcao@linutronix.de (local) Signed-off-by: Chao Liu <redacted> --- Documentation/trace/rv/monitor_rtapp.rst | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/Documentation/trace/rv/monitor_rtapp.rst b/Documentation/trace/rv/monitor_rtapp.rst
index 238b59395ff5..234ed4d581ac 100644
--- a/Documentation/trace/rv/monitor_rtapp.rst
+++ b/Documentation/trace/rv/monitor_rtapp.rst@@ -67,6 +67,8 @@ thread to sleep for one of the following reasons: variables as safe for real-time. As an alternative, the librtpi library exists to provide a conditional variable implementation that is correct for real-time applications in Linux. + - Real-time thread waiting for events using `epoll_wait`, which the monitor + accepts as a valid sleeping reason for real-time tasks. Beside the reason for sleeping, the eventual waker should also be real-time-safe. Namely, one of:
@@ -114,6 +116,10 @@ The monitor's specification is:: ALLOWLIST = BLOCK_ON_RT_MUTEX or FUTEX_LOCK_PI +`ABORT_SLEEP` represents a task restoring its state to `TASK_RUNNING` before +entering the scheduler. In this case, the task does not actually block, so the +monitor treats the aborted sleep attempt as valid. + Beside the scenarios described above, this specification also defines an allow list to handle some special cases:
base-commit: 248951ddc14de84de3910f9b13f51491a8cd91df prerequisite-patch-id: d8b6c952a954662852e6b0684e0a3386eaab7f41 prerequisite-patch-id: 940f7637aeabe4ba15a09c048c6f48138406f332 prerequisite-patch-id: b99812692691f76d825778e01a2e771e058febd6 prerequisite-patch-id: 512c300dce2cb74ac9cc007f9234aa507ef5c008 -- 2.54.0