[PATCH v4 0/3] *** Latency histograms - IRQSOFF,PREEMPTOFF ***
From: Binoy Jayan
Date: Tue Aug 30 2016 - 06:29:00 EST
Hi,
Thank you Daniel for reviewing v3 throroughly.
These set of patches [v4] capture latency events caused by interrupts and
premption disabled in kernel. The patches are based on the hist trigger
feature developed by Tom Zanussi.
v3: https://lkml.org/lkml/2016/8/29/50
v2: https://lkml.org/lkml/2016/8/24/296
Mount Debugfs
mount -t debugfs nodev /sys/kernel/debug
Examples of triggers:
echo 'hist:key=latency.log2:val=hitcount:sort=latency' > /sys/kernel/debug/tracing/events/latency/latency_preempt/trigger
echo 'hist:key=cpu,latency:val=hitcount:sort=latency if cpu==1' > /sys/kernel/debug/tracing/events/latency/latency_preempt/trigger
echo 'hist:key=ltype,cpu:val=latency:sort=ltype,cpu if ltype==0' > /sys/kernel/debug/tracing/events/latency/latency_preempt/trigger
Histogram output:
cat /sys/kernel/debug/tracing/events/latency/latency_preempt/hist
Changes from v3 as per comments from Daniel
- A few coding style changes
- Dropped the field 'cpu' from the event format fields.
TODO:
1. perf interface. Not sure if this is needed
2. Latency histograms - process wakeup latency
Binoy
Binoy Jayan (2):
tracing: Add trace_irqsoff tracepoints
tracing: Histogram for missed timer offsets
Daniel Wagner (1):
tracing: Deference pointers without RCU checks
include/linux/hrtimer.h | 3 ++
include/linux/rculist.h | 36 +++++++++++++++++++++
include/linux/tracepoint.h | 4 +--
include/trace/events/latency.h | 64 +++++++++++++++++++++++++++++++++++++
kernel/time/hrtimer.c | 40 +++++++++++++++++++++++
kernel/trace/trace_events_filter.c | 4 +--
kernel/trace/trace_events_trigger.c | 6 ++--
kernel/trace/trace_irqsoff.c | 42 ++++++++++++++++++++++++
8 files changed, 192 insertions(+), 7 deletions(-)
create mode 100644 include/trace/events/latency.h
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