[RFD 0/5] Add latency histogram

From: Daniel Wagner
Date: Thu Apr 30 2015 - 06:06:35 EST


I would like to discuss a possible way of getting the feature of the
latecy_hist.patch [1] added to mainline.

"Latency histograms are primarily relevant in the context of real-time
enabled kernels (CONFIG_PREEMPT/CONFIG_PREEMPT_RT)and are used in the
quality management of the Linux real-time capabilities."

Steven pointed out that this might be doable based on Tom Zanussi's
"[PATCH v4 0/7] tracing: 'hist' triggers" [2].

Here are my findings. It was not too complicated to get it working,
though I had to add some hacks. I have added comments to each patch.


[2] https://lkml.org/lkml/2015/4/10/591
[1] https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit/?h=v3.14-rt-rebase&id=56d50cc34943bbba12b8c5942ee1ae3b29f73acb

Daniel Wagner (4):
tracing: Add support to sort on the key
tracing: Add option to quantize key values
tracing: Deference pointers without RCU checks
tracing: Add trace_irqsoff tracepoints

Tom Zanussi (1):
tracing: 'hist' triggers

include/linux/rculist.h | 36 +++++++++++++++++++++++++++++
include/linux/tracepoint.h | 4 ++--
include/trace/events/latency.h | 40 ++++++++++++++++++++++++++++++++
kernel/trace/trace_events_hist.c | 46 +++++++++++++++++++++++++++++++++----
kernel/trace/trace_events_trigger.c | 18 +++++++++------
kernel/trace/trace_irqsoff.c | 38 ++++++++++++++++++++++++++++++
6 files changed, 168 insertions(+), 14 deletions(-)
create mode 100644 include/trace/events/latency.h


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