From 8df2d75e6ee174017318148c5c643d093043c9d6 Mon Sep 17 00:00:00 2001 From: Changbin Du Date: Sat, 17 Feb 2018 13:39:48 +0800 Subject: [PATCH] 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 Signed-off-by: Changbin Du Signed-off-by: Jonathan Corbet --- ...{hwlat_detector.txt => hwlat_detector.rst} | 26 +++++++++++-------- Documentation/trace/index.rst | 1 + 2 files changed, 16 insertions(+), 11 deletions(-) rename Documentation/trace/{hwlat_detector.txt => hwlat_detector.rst} (83%) diff --git a/Documentation/trace/hwlat_detector.txt b/Documentation/trace/hwlat_detector.rst similarity index 83% rename from Documentation/trace/hwlat_detector.txt rename to 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