summaryrefslogtreecommitdiff
path: root/Documentation/trace
diff options
context:
space:
mode:
authorChangbin Du <changbin.du@intel.com>2018-02-17 13:39:48 +0800
committerJonathan Corbet <corbet@lwn.net>2018-03-07 10:26:14 -0700
commit8df2d75e6ee174017318148c5c643d093043c9d6 (patch)
treec1c75e1dd053cfbf5428988de956aa96366e53d2 /Documentation/trace
parented657c1cbcf3a7a0daa89dff9be44c4f110e6a3d (diff)
trace doc: convert trace/hwlat_detector.txt to rst fromat
This converts the plain text documentation to reStructuredText format and add it into Sphinx TOC tree. No essential content change. Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Changbin Du <changbin.du@intel.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation/trace')
-rw-r--r--Documentation/trace/hwlat_detector.rst (renamed from Documentation/trace/hwlat_detector.txt)26
-rw-r--r--Documentation/trace/index.rst1
2 files changed, 16 insertions, 11 deletions
diff --git a/Documentation/trace/hwlat_detector.txt b/Documentation/trace/hwlat_detector.rst
index 3207717a0d1a..5739349649c8 100644
--- a/Documentation/trace/hwlat_detector.txt
+++ b/Documentation/trace/hwlat_detector.rst
@@ -1,4 +1,8 @@
-Introduction:
+=========================
+Hardware Latency Detector
+=========================
+
+Introduction
-------------
The tracer hwlat_detector is a special purpose tracer that is used to
@@ -28,7 +32,7 @@ Note that the hwlat detector should *NEVER* be used in a production environment.
It is intended to be run manually to determine if the hardware platform has a
problem with long system firmware service routines.
-Usage:
+Usage
------
Write the ASCII text "hwlat" into the current_tracer file of the tracing system
@@ -36,16 +40,16 @@ Write the ASCII text "hwlat" into the current_tracer file of the tracing system
redefine the threshold in microseconds (us) above which latency spikes will
be taken into account.
-Example:
+Example::
# echo hwlat > /sys/kernel/tracing/current_tracer
# echo 100 > /sys/kernel/tracing/tracing_thresh
The /sys/kernel/tracing/hwlat_detector interface contains the following files:
-width - time period to sample with CPUs held (usecs)
- must be less than the total window size (enforced)
-window - total period of sampling, width being inside (usecs)
+ - width - time period to sample with CPUs held (usecs)
+ must be less than the total window size (enforced)
+ - window - total period of sampling, width being inside (usecs)
By default the width is set to 500,000 and window to 1,000,000, meaning that
for every 1,000,000 usecs (1s) the hwlat detector will spin for 500,000 usecs
@@ -67,11 +71,11 @@ The following tracing directory files are used by the hwlat_detector:
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)
+ - 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
diff --git a/Documentation/trace/index.rst b/Documentation/trace/index.rst
index 4b3d690d15f3..eabbbafaa36e 100644
--- a/Documentation/trace/index.rst
+++ b/Documentation/trace/index.rst
@@ -18,3 +18,4 @@ Linux Tracing Technologies
events-nmi
events-msr
mmiotrace
+ hwlat_detector