From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com,
bobby.prani@gmail.com,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 3/6] documentation: Update NO_HZ_FULL interaction with POSIX timers
Date: Tue, 3 Mar 2015 08:37:37 -0800 [thread overview]
Message-ID: <1425400660-6380-3-git-send-email-paulmck@linux.vnet.ibm.com> (raw)
In-Reply-To: <1425400660-6380-1-git-send-email-paulmck@linux.vnet.ibm.com>
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
POSIX timers are no longer starved on adaptive-ticks CPUs. Instead, they
prevent affected CPUs from entering adaptive-ticks mode. This commit
therefore updates the NO_HZ.txt documentation.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
Documentation/timers/NO_HZ.txt | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/Documentation/timers/NO_HZ.txt b/Documentation/timers/NO_HZ.txt
index cca122f25120..6eaf576294f3 100644
--- a/Documentation/timers/NO_HZ.txt
+++ b/Documentation/timers/NO_HZ.txt
@@ -158,13 +158,9 @@ not come for free:
to the need to inform kernel subsystems (such as RCU) about
the change in mode.
-3. POSIX CPU timers on adaptive-tick CPUs may miss their deadlines
- (perhaps indefinitely) because they currently rely on
- scheduling-tick interrupts. This will likely be fixed in
- one of two ways: (1) Prevent CPUs with POSIX CPU timers from
- entering adaptive-tick mode, or (2) Use hrtimers or other
- adaptive-ticks-immune mechanism to cause the POSIX CPU timer to
- fire properly.
+3. POSIX CPU timers prevent CPUs from entering adaptive-tick mode.
+ Real-time applications needing to take actions based on CPU time
+ consumption need to use other means of doing so.
4. If there are more perf events pending than the hardware can
accommodate, they are normally round-robined so as to collect
--
1.8.1.5
next prev parent reply other threads:[~2015-03-03 16:37 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-03 16:37 [PATCH tip/core/rcu 0/6] Documentation updates for 3.21^W4.1 Paul E. McKenney
2015-03-03 16:37 ` [PATCH tip/core/rcu 1/6] documentation: Update rcutree.kthread_prio for grace-period kthread use Paul E. McKenney
2015-03-03 16:37 ` [PATCH tip/core/rcu 2/6] documentation: Update based on on-demand vmstat workers Paul E. McKenney
2015-03-03 16:37 ` Paul E. McKenney [this message]
2015-03-03 16:37 ` [PATCH tip/core/rcu 4/6] documentation: Update per-CPU kthreads documentation Paul E. McKenney
2015-03-03 16:37 ` [PATCH tip/core/rcu 5/6] documentation: Clarify memory-barrier semantics of atomic operations Paul E. McKenney
2015-03-03 16:37 ` [PATCH tip/core/rcu 6/6] documentation: Clarify control-dependency pairing Paul E. McKenney
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