mirror of
https://github.com/ceph/ceph
synced 2024-12-26 21:43:10 +00:00
170 lines
6.0 KiB
ReStructuredText
170 lines
6.0 KiB
ReStructuredText
=========================
|
|
Tracing Ceph With BlkKin
|
|
=========================
|
|
|
|
Ceph can use Blkin, a library created by Marios Kogias and others,
|
|
which enables tracking a specific request from the time it enters
|
|
the system at higher levels till it is finally served by RADOS.
|
|
|
|
In general, Blkin implements the Dapper_ tracing semantics
|
|
in order to show the causal relationships between the different
|
|
processing phases that an IO request may trigger. The goal is an
|
|
end-to-end visualisation of the request's route in the system,
|
|
accompanied by information concerning latencies in each processing
|
|
phase. Thanks to LTTng this can happen with a minimal overhead and
|
|
in realtime. The LTTng traces can then be visualized with Twitter's
|
|
Zipkin_.
|
|
|
|
.. _Dapper: http://static.googleusercontent.com/media/research.google.com/el//pubs/archive/36356.pdf
|
|
.. _Zipkin: https://zipkin.io/
|
|
|
|
|
|
Installing Blkin
|
|
================
|
|
|
|
You can install Markos Kogias' upstream Blkin_ by hand.::
|
|
|
|
cd blkin/
|
|
make && make install
|
|
|
|
or build distribution packages using DistroReadyBlkin_, which also comes with
|
|
pkgconfig support. If you choose the latter, then you must generate the
|
|
configure and make files first.::
|
|
|
|
cd blkin
|
|
autoreconf -i
|
|
|
|
.. _Blkin: https://github.com/marioskogias/blkin
|
|
.. _DistroReadyBlkin: https://github.com/agshew/blkin
|
|
|
|
|
|
Configuring Ceph with Blkin
|
|
===========================
|
|
|
|
If you built and installed Blkin by hand, rather than building and
|
|
installing packages, then set these variables before configuring
|
|
Ceph.::
|
|
|
|
export BLKIN_CFLAGS=-Iblkin/
|
|
export BLKIN_LIBS=-lzipkin-cpp
|
|
|
|
Blkin support in Ceph is disabled by default, so you may
|
|
want to configure with something like::
|
|
|
|
./do_cmake -DWITH_BLKIN=ON
|
|
|
|
Config option for blkin must be set to true in ceph.conf to get
|
|
traces from rbd through OSDC and OSD::
|
|
|
|
rbd_blkin_trace_all = true
|
|
|
|
|
|
Testing Blkin
|
|
=============
|
|
|
|
It's easy to test Ceph's Blkin tracing. Let's assume you don't have
|
|
Ceph already running, and you compiled Ceph with Blkin support but
|
|
you didn't install it. Then launch Ceph with the ``vstart.sh`` script
|
|
in Ceph's src directory so you can see the possible tracepoints.::
|
|
|
|
cd src
|
|
OSD=3 MON=3 RGW=1 ./vstart.sh -n
|
|
lttng list --userspace
|
|
|
|
You'll see something like the following:::
|
|
|
|
UST events:
|
|
-------------
|
|
PID: 8987 - Name: ./ceph-osd
|
|
zipkin:timestamp (loglevel: TRACE_WARNING (4)) (type: tracepoint)
|
|
zipkin:keyval_integer (loglevel: TRACE_WARNING (4)) (type: tracepoint)
|
|
zipkin:keyval_string (loglevel: TRACE_WARNING (4)) (type: tracepoint)
|
|
lttng_ust_tracelog:TRACE_DEBUG (loglevel: TRACE_DEBUG (14)) (type: tracepoint)
|
|
|
|
PID: 8407 - Name: ./ceph-mon
|
|
zipkin:timestamp (loglevel: TRACE_WARNING (4)) (type: tracepoint)
|
|
zipkin:keyval_integer (loglevel: TRACE_WARNING (4)) (type: tracepoint)
|
|
zipkin:keyval_string (loglevel: TRACE_WARNING (4)) (type: tracepoint)
|
|
lttng_ust_tracelog:TRACE_DEBUG (loglevel: TRACE_DEBUG (14)) (type: tracepoint)
|
|
|
|
...
|
|
|
|
Next, stop Ceph so that the tracepoints can be enabled.::
|
|
|
|
./stop.sh
|
|
|
|
Start up an LTTng session and enable the tracepoints.::
|
|
|
|
lttng create blkin-test
|
|
lttng enable-event --userspace zipkin:timestamp
|
|
lttng enable-event --userspace zipkin:keyval_integer
|
|
lttng enable-event --userspace zipkin:keyval_string
|
|
lttng start
|
|
|
|
Then start up Ceph again.::
|
|
|
|
OSD=3 MON=3 RGW=1 ./vstart.sh -n
|
|
|
|
You may want to check that ceph is up.::
|
|
|
|
./ceph status
|
|
|
|
Now put something in using rados, check that it made it, get it back, and remove it.::
|
|
|
|
./ceph osd pool create test-blkin 8
|
|
./rados put test-object-1 ./vstart.sh --pool=test-blkin
|
|
./rados -p test-blkin ls
|
|
./ceph osd map test-blkin test-object-1
|
|
./rados get test-object-1 ./vstart-copy.sh --pool=test-blkin
|
|
md5sum vstart*
|
|
./rados rm test-object-1 --pool=test-blkin
|
|
|
|
You could also use the example in ``examples/librados/`` or ``rados bench``.
|
|
|
|
Then stop the LTTng session and see what was collected.::
|
|
|
|
lttng stop
|
|
lttng view
|
|
|
|
You'll see something like:::
|
|
|
|
[15:33:08.884275486] (+0.000225472) ubuntu zipkin:timestamp: { cpu_id = 53 }, { trace_name = "op", service_name = "Objecter", port_no = 0, ip = "0.0.0.0", trace_id = 5485970765435202833, span_id = 5485970765435202833, parent_span_id = 0, event = "osd op reply" }
|
|
[15:33:08.884614135] (+0.000002839) ubuntu zipkin:keyval_integer: { cpu_id = 10 }, { trace_name = "", service_name = "Messenger", port_no = 6805, ip = "0.0.0.0", trace_id = 7381732770245808782, span_id = 7387710183742669839, parent_span_id = 1205040135881905799, key = "tid", val = 2 }
|
|
[15:33:08.884616431] (+0.000002296) ubuntu zipkin:keyval_string: { cpu_id = 10 }, { trace_name = "", service_name = "Messenger", port_no = 6805, ip = "0.0.0.0", trace_id = 7381732770245808782, span_id = 7387710183742669839, parent_span_id = 1205040135881905799, key = "entity type", val = "client" }
|
|
|
|
|
|
Install Zipkin
|
|
===============
|
|
One of the points of using Blkin is so that you can look at the traces
|
|
using Zipkin. Users should run Zipkin as a tracepoints collector and
|
|
also a web service. The executable jar runs a collector on port 9410 and
|
|
the web interface on port 9411
|
|
|
|
Download Zipkin Package::
|
|
|
|
git clone https://github.com/openzipkin/zipkin && cd zipkin
|
|
wget -O zipkin.jar 'https://search.maven.org/remote_content?g=io.zipkin.java&a=zipkin-server&v=LATEST&c=exec'
|
|
java -jar zipkin.jar
|
|
|
|
|
|
Show Ceph's Blkin Traces in Zipkin-web
|
|
======================================
|
|
Download babeltrace-zipkin project. This project takes the traces
|
|
generated with blkin and sends them to a Zipkin collector using scribe::
|
|
|
|
git clone https://github.com/vears91/babeltrace-zipkin
|
|
cd babeltrace-zipkin
|
|
|
|
Send lttng data to Zipkin::
|
|
|
|
python3 babeltrace_zipkin.py ${lttng-traces-dir}/${blkin-test}/ust/uid/0/64-bit/ -p ${zipkin-collector-port(9410 by default)} -s ${zipkin-collector-ip}
|
|
|
|
Example::
|
|
|
|
python3 babeltrace_zipkin.py ~/lttng-traces-dir/blkin-test-20150225-160222/ust/uid/0/64-bit/ -p 9410 -s 127.0.0.1
|
|
|
|
Check Ceph traces on webpage::
|
|
|
|
Browse http://${zipkin-collector-ip}:9411
|
|
Click "Find traces"
|