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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-01-25 11:28:28 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-02-26 11:57:29 -0800
commitc25197841efe53258abb22cfd894a729a272edf9 (patch)
tree2aee40a0447d3380378b9d0e77148c3a015c352f /Documentation/timers
parent89bf5d82ed451f02329bbbb06ac365e96b18804d (diff)
downloadlinux-c25197841efe53258abb22cfd894a729a272edf9.tar.bz2
documentation: Update NO_HZ_FULL interaction with POSIX timers
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>
Diffstat (limited to 'Documentation/timers')
-rw-r--r--Documentation/timers/NO_HZ.txt10
1 files 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