Re: [lttng-dev] Lttng: display active threads in multiple cores.
you can use an ftrace-enabled kernel with lttng (maybe even just tracecompass) or perfetto to get that kind of trace https://archive.eclipse.org/tracecompass.incubator/doc/org.eclipse.tracecompass.incubator.ftrace.doc.user/User-Guide.html or https://ui.perfetto.dev/ On Wed, Mar 27, 2024, at 5:26 AM, Zvi Vered via lttng-dev wrote: > Hello, > > I have an application with 4 threads. > I'm required to display on the graph when thread starts working till it > blocks for the next semaphore. > > But without using the lttng userspace library. > > Is it possible ? > > Thank you, > Zvika > ___ > lttng-dev mailing list > lttng-dev@lists.lttng.org > https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev ___ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
Re: [lttng-dev] What is DEFINE_LTTNG_UST_SIGBUS_STATE for and other beginner questions
I got this one figured out. I used strace -fp -trace=connect on the target app to see why the connect was failing and it turns out there was a mismatch between sessiond's apps-socket paths and libust's. time to review my build environment I guess. It's very possible my docker container's path environment variables are non-standard. If I had a tiny bit of feedback to provide it would be to print out the errno and paths in the connect/bind commands in the DBG commands. I had to bust out strace to get that info. Small problem, but it could have saved me a few hours and some mailing list messages. Thank you for making this nice looking software available for free. Looking forward to playing with it some more. -Chris ___ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
Re: [lttng-dev] What is DEFINE_LTTNG_UST_SIGBUS_STATE for and other beginner questions
On Wed, Oct 4, 2023, at 3:04 PM, Kienan Stewart wrote: > Hi Chris, > > On 2023-10-04 12:56, Christopher Harvey via lttng-dev wrote: >> Hi all, >> >> I'm just getting started with lttng and have a couple of questions. My >> target is getting userspace tracepoints to work in a c++ application I >> control. I don't need kernel or system tracing. The target is running in a >> docker container I have control over as well. Running with --privileged is >> possible in my setup. I could run lttng inside the target container, outside >> on the host, or in another container on the same host. It's all the same to >> me. I don't know which setup is best, or if it even matters given that I >> don't need system or kernel traces. >> >> I am using: >> lttng-tools-2.13.11/ and lttng-ust-2.13.6/ >> with userspace-rcu-0.14.0/ >> >> There is a slight version mismatch there, I just downloaded the "-lastest" >> from the links in the guide. >> >> Here is my tracepoint provider header: >> - [SNIP] >> >> >> and the cpp: >> --- [SNIP] >> >> >> I'm suspicious of a couple of things in my setup. >> >> First, if I omit the DEFINE_LTTNG_UST_SIGBUS_STATE(); line, my program fails >> to compile with the following error: >> liblttng-ust-ctl.so: undefined reference to `lttng_ust_sigbus_state' >> > > I wasn't able to reproduce the compilation error you are seeing. Could > you describe in more detail how you are compiling and linking your > tracepoint provider and application? I just create a .o from the tracepoint provider compilation unit. I'm not making shared libraries or anything like that. More on this below. >> The getting started guide doesn't say anything about needing >> DEFINE_LTTNG_UST_SIGBUS_STATE so it makes me wonder if I have done something >> else wrong somewhere else. I ran a find *.so | xargs nm -D | grep >> lttng_ust_sigbus_state and nothing in lttng-ust provides that symbol, so it >> looks like the target application has to define it. Is that normal? >> > > If the application is actually using liblttng-ust-ctl, then it would be > normal to do the define. The header file explains that this is done to > avoid unnecessarily pre-allocating space in the thread-local storage. > https://github.com/lttng/lttng-ust/blob/master/include/lttng/ust-sigbus.h#L39 > > Traced applications typically don't link against liblttng-ust-ctl. > This ended up being one of the main problems. My final linking flags are -llttng-ust -llttng-ust-common -llttng-ust-tracepoint I didn't have a particular reason for linking against liblttng-ust-ctl before. It was a mistake. >> If I leave DEFINE_LTTNG_UST_SIGBUS_STATE in then my program compiles. If I >> run lttng-sessiond in the target container, then run lttng list --userspace >> I see no tracepoints in the list. >> > > Is your application actively running while you run `lttng list --userspace`? yes I was reading some lttng-sessiond source code and discovered -vvv as well as LTTNG_UST_DEBUG. I'm still not seeing the tracepoints show up in lttng list --userspace, but I found more hints as to why. Here is some output from my target application: liblttng_ust[454/467]: Info: sessiond not accepting connections to local apps socket (in ust_listener_thread() at lttng-ust-comm.c:1884) liblttng_ust[454/467]: Waiting for local apps sessiond (in wait_for_sessiond() at lttng-ust-comm.c:1758 These prints only happen periodically when lttng-sessiond is running. If I stop lttng-sessiond then the prints stop so there is clearly some communication happening. Apparently this gets printed when there is an ECONNREFUSED from lttng-sessiond. I haven't gotten much further than that right now. I have pasted the output from sessiond -vvv here: https://pastebin.com/raw/ayJJ2J9p thank you for your time, Chris ___ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
[lttng-dev] What is DEFINE_LTTNG_UST_SIGBUS_STATE for and other beginner questions
Hi all, I'm just getting started with lttng and have a couple of questions. My target is getting userspace tracepoints to work in a c++ application I control. I don't need kernel or system tracing. The target is running in a docker container I have control over as well. Running with --privileged is possible in my setup. I could run lttng inside the target container, outside on the host, or in another container on the same host. It's all the same to me. I don't know which setup is best, or if it even matters given that I don't need system or kernel traces. I am using: lttng-tools-2.13.11/ and lttng-ust-2.13.6/ with userspace-rcu-0.14.0/ There is a slight version mismatch there, I just downloaded the "-lastest" from the links in the guide. Here is my tracepoint provider header: - #undef LTTNG_UST_TRACEPOINT_PROVIDER #define LTTNG_UST_TRACEPOINT_PROVIDER my_provider #undef LTTNG_UST_TRACEPOINT_INCLUDE #define LTTNG_UST_TRACEPOINT_INCLUDE "./myLttngUstProvider.hpp" #if !defined(_TP_H) || defined(LTTNG_UST_TRACEPOINT_HEADER_MULTI_READ) #define _TP_H #include "lttng/tracepoint.h" LTTNG_UST_TRACEPOINT_EVENT( /* Tracepoint provider name */ my_provider, /* Tracepoint name */ test, /* Input arguments */ LTTNG_UST_TP_ARGS( int, arg1 ), /* Output event fields */ LTTNG_UST_TP_FIELDS( lttng_ust_field_integer(int, arg1, arg1) ) ) #endif /* _TP_H */ #include "lttng/tracepoint-event.h" and the cpp: --- #define LTTNG_UST_TRACEPOINT_CREATE_PROBES #define LTTNG_UST_TRACEPOINT_DEFINE #include "myLttngUstProvider.hpp" #include "lttng/ust-sigbus.h" DEFINE_LTTNG_UST_SIGBUS_STATE(); I'm suspicious of a couple of things in my setup. First, if I omit the DEFINE_LTTNG_UST_SIGBUS_STATE(); line, my program fails to compile with the following error: liblttng-ust-ctl.so: undefined reference to `lttng_ust_sigbus_state' The getting started guide doesn't say anything about needing DEFINE_LTTNG_UST_SIGBUS_STATE so it makes me wonder if I have done something else wrong somewhere else. I ran a find *.so | xargs nm -D | grep lttng_ust_sigbus_state and nothing in lttng-ust provides that symbol, so it looks like the target application has to define it. Is that normal? If I leave DEFINE_LTTNG_UST_SIGBUS_STATE in then my program compiles. If I run lttng-sessiond in the target container, then run lttng list --userspace I see no tracepoints in the list. I tried looking at the lttng source code but there is a lot there. I'm looking for some next steps for debugging this setup. What are some things I could check to make sure the lttng daemon is running properly? What is the mechanism for advertising tracepoints to the lttng daemon? Is it possible that docker has somehow interfered with the lttng ipc mechanism? It would be a tiny bit more convenient for me to simply deploy lttng-tools as a separate container, can I consider doing that instead? I'm not running anything as root, just a normal user. I appreciate any and all guidance. Looking forward to using this neat looking tool. -Chris ___ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
