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| author | Frederic Weisbecker <fweisbec@gmail.com> | 2012-12-18 20:32:19 +0400 |
|---|---|---|
| committer | Frederic Weisbecker <fweisbec@gmail.com> | 2013-03-21 18:38:33 +0400 |
| commit | a831881be220358a1d28c5d95d69449fb6d623ca (patch) | |
| tree | 769ab069e2837a9bd3613046110468cd87c8c3fa /Documentation/kernel-parameters.txt | |
| parent | a8d7ad52a7befbde896276d05c75c90fed48b5bf (diff) | |
| download | linux-a831881be220358a1d28c5d95d69449fb6d623ca.tar.xz | |
nohz: Basic full dynticks interface
For extreme usecases such as Real Time or HPC, having
the ability to shutdown the tick when a single task runs
on a CPU is a desired feature:
* Reducing the amount of interrupts improves throughput
for CPU-bound tasks. The CPU is less distracted from its
real job, from an execution time and from the cache point
of views.
* This also improve latency response as we have less critical
sections.
Start with introducing a very simple interface to define
full dynticks CPU: use a boot time option defined cpumask
through the "nohz_extended=" kernel parameter. CPUs that
are part of this range will have their tick shutdown
whenever possible: provided they run a single task and
they don't do kernel activity that require the periodic
tick. These details will be later documented in
Documentation/*
An online CPU must be kept outside this range to handle the
timekeeping.
Suggested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Gilad Ben Yossef <gilad@benyossef.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'Documentation/kernel-parameters.txt')
| -rw-r--r-- | Documentation/kernel-parameters.txt | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 4609e81dbc37..231698feaddc 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1913,6 +1913,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Valid arguments: on, off Default: on + nohz_extended= [KNL,BOOT] + In kernels built with CONFIG_NO_HZ_EXTENDED=y, set + the specified list of CPUs whose tick will be stopped + whenever possible. You need to keep at least one online + CPU outside the range to maintain the timekeeping. + noiotrap [SH] Disables trapped I/O port accesses. noirqdebug [X86-32] Disables the code which attempts to detect and |