[lttng-dev] Relayd trace drops

Aravind HT aravind.ht at gmail.com
Wed Dec 9 04:34:59 EST 2015


Sorry about that, not sure how it got missed.
Here it is.


# This needs a two node set up (1. local current node 2. remote node )
# relayd runs on the current node where traces are captured from the remote
node
# remote node runs test applications which generate traces.
# the launch_script_RN is executed on the current node and uses ssh  to
execute commands on the remote node. So this part may not work in every
case and may prompt for a password.
# if experiencing problems with ssh , kindly check
http://serverfault.com/questions/241588/how-to-automate-ssh-login-with-password

# ====================       To Run        =============================
launch_script_RN.py self_profile -c /tmp/configFile.txt



# configFile.txt is the file which has configuration params that
launchScript
# needs to configure lttng sessions. Below is an explanation of the
different options.
# ===================     configFile.txt   =============================

[section1]
# final out put file path
OutputFile = /tmp/Final_report.txt
# the remote node hostname on which test applications run and the test
sessions will be created; this should be something that could be used with
ssh. Traces will be transported from this node to the lttng_relayd running
on the current node.
Node = MY_REMOTE_NODE
# Sub buffer size to start this with
SubBufSize = 16k
# Sub buffer count
SubBufCount = 4
# per uid buffer
BufferScheme = --buffers-uid
# yes
EnableTracing = yes
# Bit rate of the test applications. Comman seperated example "1, 3, 3, 50"
sayss 4 test applications producing 1, 3, 3, and 50 Kb/s traces.
# So with the below, we just start with 1 test application producing 10 kb/s
TestApps = 10
# session life time in seonds
TestTime = 10
# Max number of successive sessions to configure. if n then n-1 sessions
are run, ex MaxRun = 2 will run 1 session.
MaxRun = 100


# ====================  Place the following files under ===============

# /tmp on the remote node
clean_RemNode_apps.sh
report_lttng_script.sh

# rest of the scripts under /usr/sbin on the current local node on which
lttng_realyd runs
# Define a trace point MY_TRACE to take a single string arg with
LOG_TEST_APP_PROFILING as the provider, compile test lttng_testApp and
place it under /usr/sbin of the remote host

# in launch_script_RN.py change currentNodeIP to the IP address on which
relayd is receiving, default ports are used.

# lttng_relayd is started as
/usr/bin/lttng-relayd -o /var/log/lttng-traces -d

# lttng_sessiond is started as
/usr/bin/lttng-sessiond --consumerd32-path
/usr/lib/lttng/libexec/lttng-consumerd --consumerd32-libdir /usr/lib/
--consumerd64-path /usr/lib64/lttng/libexec/lttng-consumerd
--consumerd64-libdir /usr/lib64/ -b --no-kernel




Regards,
Aravind.

On Wed, Dec 9, 2015 at 12:57 AM, Jonathan Rajotte Julien <
Jonathan.rajotte-julien at efficios.com> wrote:

> Hi Aravind,
>
> There is no README in the archive you sent.
>
> Cheers
>
> On 2015-12-08 07:51 AM, Aravind HT wrote:
>
>> Hi,
>>
>> I am trying to upgrade in parallel, but this issue may still be present
>> after I upgrade or may be temporarily masked. So I need to find the root
>> cause for this and then see if its available on the latest before
>> committing to upgrade.
>>
>> There is another issue i'm hitting, the lttng list command hangs after
>> lttng destroy session when running the profiling.
>>
>> I found that consumerd 64 goes into an infinite loop waiting to flush
>> metadata in lttng_ustconsumer_recv_metadata() :: while
>> (consumer_metadata_cache_flushed(channel, offset + len, timer)) .
>> In consumer_metadata_cache, channel->metadata_stream->endpoint_status is
>> CONSUMER_ENDPOINT_ACTIVE, metadata_stream->ust_metadata_pushed is 0 with
>> offset having some value. This call always returns a 1 from the last else{}
>> block resulting in an infinite loop. Upon searching the forum, I found the
>> same issue being reported here :
>> https://www.mail-archive.com/lttng-dev@lists.lttng.org/msg07982.html
>>
>> Regards,
>> Aravind.
>>
>>
>> On Tue, Dec 8, 2015 at 12:43 AM, Jonathan Rajotte <
>> jonathan.r.julien at gmail.com> wrote:
>>
>>     Hi Aravind,
>>
>>     Did you have the chance to upgrade to 2.6.1.If so where you able
>>     to reproduce?
>>
>>     Cheers
>>
>>     On Mon, Dec 7, 2015 at 1:07 PM, Aravind HT <aravind.ht at gmail.com>
>>     wrote:
>>
>>         Hi,
>>
>>         I have attached the complete profiling scripts here, its a bit
>>         shabby, im new to python.
>>
>>         There is a README which has the details on how to execute it.
>>         Im using a Yocto 1.6 on x86_64 platforms on both the nodes.
>>
>>
>>         Running this script when there are other sessions running
>>         seems to reproduce this problem easily.
>>         Please try it and let me know if you have any issues
>>         reproducing the problem.
>>
>>         Regards,
>>         Aravind.
>>
>>         On Sat, Dec 5, 2015 at 5:23 PM, Jérémie Galarneau
>>         <jeremie.galarneau at efficios.com
>>         <mailto:jeremie.galarneau at efficios.com>> wrote:
>>
>>             On Fri, Dec 4, 2015 at 11:06 PM, Aravind HT
>>             <aravind.ht at gmail.com <mailto:aravind.ht at gmail.com>> wrote:
>>             > I am using 2.6.0 .I will try to share the code that I'm
>>             using here in some
>>             > time. If there are any specific fixes that are relevant
>>             to this issue, see
>>             > if you can provide a link to them. I would ideally like
>>             to try them out
>>             > before trying a full upgrade to the latest versions.
>>
>>             Hi,
>>
>>             Can you provide more information on the system? Which
>>             distribution,
>>             architecture, kernel version?
>>
>>             The verbose sessiond logs might help pinpoint any
>>             unexpected behaviour
>>             here (are all applications registering as expected?).
>>
>>             Jérémie
>>
>>             >
>>             > On Fri, Dec 4, 2015 at 6:11 PM, Jérémie Galarneau
>>             > <jeremie.galarneau at efficios.com
>>             <mailto:jeremie.galarneau at efficios.com>> wrote:
>>             >>
>>             >> Hi Aravind,
>>             >>
>>             >> Can't say I have looked at everything you sent yet, but
>>             as a
>>             >> preemptive question, which version are we talking about
>>             here? 2.6.0 or
>>             >> 2.6.1? 2.6.1 contains a lot of relay daemon fixes.
>>             >>
>>             >> Thanks,
>>             >> Jérémie
>>             >>
>>             >> On Thu, Dec 3, 2015 at 7:01 AM, Aravind HT
>>             <aravind.ht at gmail.com> wrote:
>>             >> > Hi,
>>             >> >
>>             >> > I am trying to obtain the performance characteristics
>>             of lttng with the
>>             >> > use
>>             >> > of test applications. Traces are being produced on a
>>             local node and
>>             >> > delivered to relayd that is running on a separate
>>             node for storage.
>>             >> >
>>             >> > An lttng session with the test applications producing
>>             an initial bit
>>             >> > rate of
>>             >> > 10 kb/s is started and run for about 30 seconds. The
>>             starting sub-buffer
>>             >> > size is kept at 128 kb and sub-buf count at 4. The
>>             session is then
>>             >> > stopped
>>             >> > and destroyed and traces are analyzed to see if there
>>             are any drops.
>>             >> > This is
>>             >> > being done in a loop with every subsequent session
>>             having an increment
>>             >> > of 2
>>             >> > kb/s as long as there are no drops. If there are
>>             drops, I increase the
>>             >> > buffer size by a factor of x2 without incrementing
>>             the bit rate.
>>             >> >
>>             >> > I see trace drops happening consistently with test
>>             apps producing traces
>>             >> > at
>>             >> > less than 40 kb/s, it doesnt seem to help even if I
>>             started with 1mb x 4
>>             >> > sub-buffers.
>>             >> >
>>             >> > Analysis :
>>             >> >
>>             >> > I have attached the lttng_relayd , lttng_consumerd_64
>>             logs and the
>>             >> > entire
>>             >> > trace directory, hope you will be able to view it.
>>             >> > I have modified lttng_relayd code to dump the traces
>>             being captured in
>>             >> > the
>>             >> > lttng_relayd logs along with debug info.
>>             >> >
>>             >> > Each test app is producing logs in the form of  :
>>             >> > "TraceApp PID - 31940 THID - 31970 @threadRate - 1032
>>             b/s appRate - 2079
>>             >> > b/s
>>             >> > threadTraceNum - 9 appTraceNum - 18  sleepTime - 192120"
>>             >> >
>>             >> > The test application PID, test application thread id,
>>             thread bit rate,
>>             >> > test
>>             >> > app bit rate, thread trace number and application
>>             trace number s are
>>             >> > part of
>>             >> > the trace. So in the above trace, the thread is
>>             producing at 1 kb/s and
>>             >> > the
>>             >> > whole test app is producing at 2 kb/s.
>>             >> >
>>             >> > If we look at the babeltrace out put, we see that the
>>             Trace with
>>             >> > TraceApp
>>             >> > PID - 31940 appTraceNum 2 is missing , with 1, 3, 4,
>>             5 and so on being
>>             >> > successfully captured.
>>             >> > I looked at the lttng_relayd logs and found that
>>             trace of "appTraceNum
>>             >> > 2" is
>>             >> > not delivered/generated by the consumerd to the
>>             relayd in sequence with
>>             >> > other traces. To rule out that this is not a test
>>             application problem,
>>             >> > you
>>             >> > can look at line ltttng_relayd log : 12778 and see
>>             traces from
>>             >> > appTraceNum -
>>             >> > 1 to appTraceNum - 18 including the appTraceNum 2 are
>>             "re-delivered" by
>>             >> > the
>>             >> > consumerd to the relayd.
>>             >> > Essentially, I see appTraceNum 1 through appTraceNum
>>             18 being delivered
>>             >> > twice, once individually where appTraceNum 2 is
>>             missing and once as a
>>             >> > group
>>             >> > at line 12778 where its present.
>>             >> >
>>             >> >
>>             >> > Request help with
>>             >> > 1. why traces are delivered twice, is it by design or
>>             a genuine problem
>>             >> > ?
>>             >> > 2. how to avoid traces being dropped even though
>>             buffers are
>>             >> > sufficiently
>>             >> > large enough ?
>>             >> >
>>             >> >
>>             >> > Regards,
>>             >> > Aravind.
>>             >> >
>>             >> > _______________________________________________
>>             >> > lttng-dev mailing list
>>             >> > lttng-dev at lists.lttng.org
>>             >> >
>> http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
>>             >> >
>>             >>
>>             >>
>>             >>
>>             >> --
>>             >> Jérémie Galarneau
>>             >> EfficiOS Inc.
>>             >> http://www.efficios.com
>>             >
>>             >
>>
>>
>>
>>             --
>>             Jérémie Galarneau
>>             EfficiOS Inc.
>>             http://www.efficios.com
>>
>>
>>
>>         _______________________________________________
>>         lttng-dev mailing list
>>         lttng-dev at lists.lttng.org <mailto:lttng-dev at lists.lttng.org>
>>         http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
>>
>>
>>
>>
>>     --     Jonathan Rajotte Julien
>>
>>
>>
>>
>> _______________________________________________
>> lttng-dev mailing list
>> lttng-dev at lists.lttng.org
>> http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
>>
>
> --
> Jonathan R. Julien
> Efficios
>
>
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