Hi, On 2017-09-20 05:12 AM, liguang li wrote: > > > On Tue, Sep 19, 2017 at 10:57 PM, Jonathan Rajotte-Julien > <[email protected] > <mailto:[email protected]>> wrote: > > On Tue, Sep 19, 2017 at 03:53:27PM +0800, liguang li wrote: > > Hi, > > On Mon, Sep 18, 2017 at 11:18 PM, Jonathan Rajotte-Julien > > <[1][email protected] > <mailto:[email protected]>> wrote: > > > > Hi, > > On Mon, Sep 18, 2017 at 11:32:07AM +0800, liguang li wrote: > > > Hi, > > > > > > Create a session in live-reading mode, run a application which > > having very > > > high event throughput, then prints > > > the events with babeltrace. We found the live trace viewer are > > viewing > > > events a few seconds ago, and as time > > > > Could you provide us the version used for babeltrace, lttng-tools > and > > lttng-ust? > > > > Babeltrace: 1.5.1 > > Update to babeltrace 1.5.3. > > > Lttng-tools: 2.8.6 > > Update to lttng-tools 2.8.8 > > > Lttng-ust: 2.8.2 > > > > > goes on, the delay will be bigger and bigger. > > > > A similar issues was observed a couple months ago, which implicated > > multiple delayed ack > > problems during communication between lttng-relayd and babeltrace. > > > > The following fixes were merged: > > > > [1] > > > [2]https://github.com/lttng/lttng-tools/commit/b6025e9476332b75eb8184345c3eb3e924780088 > > <https://github.com/lttng/lttng-tools/commit/b6025e9476332b75eb8184345c3eb3e924780088> > > [2] > > > [3]https://github.com/efficios/babeltrace/commit/de417d04317ca3bc30f59685a9d19de670e4b11d > > <https://github.com/efficios/babeltrace/commit/de417d04317ca3bc30f59685a9d19de670e4b11d> > > [3] > > > [4]https://github.com/efficios/babeltrace/commit/4594dbd8f7c2af2446a3e310bee74ba4a2e9d648 > > <https://github.com/efficios/babeltrace/commit/4594dbd8f7c2af2446a3e310bee74ba4a2e9d648> > > > > In the event that you are already using an updated version of > babeltrace > > and > > lttng-tools, it would be pertinent to provide us with a simple > > reproducer so we > > can assess the issue. > > The version you are using does not include the mentioned fixes. Please > update > and redo your experiment. > > > Test this issue in the version you have listed, the issue still exists.
Given that previous versions had a major timing problem there I would expect to have some improvement. In that case, we will need a lot more information on your benchmarking strategy. We will need a simple reproducer, your benchmark code (r,gnuplot etc.), your overall methodology to be able to reproduce the issue locally. Otherwise, it will be very hard to come to any conclusion. > > > Cheers > > > > > > > Steps: > > lttng create session --live -U net://* > > lttng enable-channel -s session -u ch1 > > lttng enable-event -s session -c ch1 -u -a > > lttng start > > > > Run a high event throughput application, which is multithreaded > > application> > > In the multithreaded application, each tracepoint will have the wall > time of the system,then we can easily reproduce this issue through > comparing the time of recorded event and the system wall time. > > > > babeltrace -i lttng-live net://* > > > > After a while, we found the timestamp of the event in the > babeltrace is > > different with the time in host > > which run the application. And the delay will be bigger and bigger > with > > time goes. > > > > > > Cheers > > > I checked the source code, found Babeltrace in live-reading > mode > > will read > > > the recorded events in the CTF > > > files, and then parse and print it in a single thread. The > process > > is a > > > little slow, do you have any ideas to > > > improve the process. > > > From my understanding of the source code, the process of parse and > print event will consume a lot of time. For example, the multithreaded > application will consume 3 CPUs, in a specified time,3 subbuffers will > be filled and sent to lttng-relayd daemon, recorded into the CTF files. > If in the specified time, babeltrace only handled 2 subbuffers' event, > thenthe issue will happens. Did you perform a bisection for where the delay come from? Reception of packet? formatting of event? What is the throughput of the application? How many tracepoint definition? Does babeltrace catch up if a quiescent period is given? Could you provide us with statistics, timing data, etc.? What type of delay are we talking about? -- Jonathan R. Julien Efficios _______________________________________________ lttng-dev mailing list [email protected] https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
