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| author | Steven Rostedt (Red Hat) <rostedt@goodmis.org> | 2016-07-15 21:48:56 +0200 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2016-09-02 18:47:54 +0200 |
| commit | 0330f7aa8ee63d0c435c0cb4e47ea06235ee4b7f (patch) | |
| tree | 67fa852b52a5c4c09ec74f6ba38c7b44f14af180 /Documentation/trace | |
| parent | tracing: Add documentation for hwlat_detector tracer (diff) | |
| download | linux-0330f7aa8ee63d0c435c0cb4e47ea06235ee4b7f.tar.xz linux-0330f7aa8ee63d0c435c0cb4e47ea06235ee4b7f.zip | |
tracing: Have hwlat trace migrate across tracing_cpumask CPUs
Instead of having the hwlat detector thread stay on one CPU, have it migrate
across all the CPUs specified by tracing_cpumask. If the user modifies the
thread's CPU affinity, the migration will stop until the next instance that
the tracer is instantiated. The migration happens at the end of each window
(period).
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'Documentation/trace')
| -rw-r--r-- | Documentation/trace/hwlat_detector.txt | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/trace/hwlat_detector.txt b/Documentation/trace/hwlat_detector.txt index c02e8ef800cf..3207717a0d1a 100644 --- a/Documentation/trace/hwlat_detector.txt +++ b/Documentation/trace/hwlat_detector.txt @@ -69,5 +69,11 @@ in /sys/kernel/tracing: tracing_threshold - minimum latency value to be considered (usecs) tracing_max_latency - maximum hardware latency actually observed (usecs) + tracing_cpumask - the CPUs to move the hwlat thread across hwlat_detector/width - specified amount of time to spin within window (usecs) hwlat_detector/window - amount of time between (width) runs (usecs) + +The hwlat detector's kernel thread will migrate across each CPU specified in +tracing_cpumask between each window. To limit the migration, either modify +tracing_cpumask, or modify the hwlat kernel thread (named [hwlatd]) CPU +affinity directly, and the migration will stop. |