diff options
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-01-25 11:28:28 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-02-26 11:57:29 -0800 |
| commit | c25197841efe53258abb22cfd894a729a272edf9 (patch) | |
| tree | 2aee40a0447d3380378b9d0e77148c3a015c352f /Documentation/timers/NO_HZ.txt | |
| parent | 89bf5d82ed451f02329bbbb06ac365e96b18804d (diff) | |
| download | lwn-c25197841efe53258abb22cfd894a729a272edf9.tar.gz lwn-c25197841efe53258abb22cfd894a729a272edf9.zip | |
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/NO_HZ.txt')
| -rw-r--r-- | Documentation/timers/NO_HZ.txt | 10 |
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 |