Hello Yordan, Thanks again for your precious answers! I got your point. Honestly, I would like to avoid to register the `sched_switch`. Because of my current needs, I prefer to record few things (with strong filters). So, often, I may have in my trace big temporal gaps in which I don't know whether a task X is still running with a function that I don't record, or a task Y that I don't record at all, or idle. In all these `uncertain` cases, I'd like to simply color the timebar with a gray shape. If that doesn't annoy you too much, may you give me some hints about writing a Kernelshark's plugin? Thanks! Matteo -----Original Message----- From: Yordan Karadzhov [mailto:y.karadz@xxxxxxxxx] Sent: Tuesday, September 6, 2022 8:01 PM To: Matteo Bertolino <matteo.bertolino@xxxxxxxxxx>; linux-trace-users@xxxxxxxxxxxxxxx Subject: Re: Kernelshark: funcgraph_exit events don't seem to exit? Hi Matteo, I confirm that the logic that you want can be implemented via plugin. However, there is even simpler way to accomplish what you want. When recording your trace, enable the 'sched_switch' events. This way in your data you will know exactly when the execution switches form one task to another (or to idle). The good thing here is that KernelShark already has a plugin for 'sched_switch' end you will see a the behavior that you expect. cheers, Y. On 9/6/22 14:57, Matteo Bertolino wrote: > Dear Yordan, > Thanks for your reply! > > I would like to do a double check to be sure that we're on the same rail. > Can you please take my screenshot again? Between 8.090000 and 8.130000 the trace doesn't provide any information. > > We don't know whether: > A) task1 continues after the end of foo1 running something else that > is not traced Or > B) The CPU is idle/a non-traced task is running. > > Today, the default behavior of kernelshark is A). Indeed, in my screenshot, the bar indicated by the light-blue arrow is red. > > Instead, I wish to code a plugin with a third option: > C) when we do not know what happens, just color with gray. > > Do your instructions cover this case? > If so, I would like to have some hints and I will try to implement it > :-) > > Best Regards, > Matteo > > -----Original Message----- > From: Yordan Karadzhov [mailto:y.karadz@xxxxxxxxx] > Sent: Tuesday, September 6, 2022 12:45 PM > To: Matteo Bertolino <matteo.bertolino@xxxxxxxxxx>; > linux-trace-users@xxxxxxxxxxxxxxx > Subject: Re: Kernelshark: funcgraph_exit events don't seem to exit? > > Hi Matteo, > Thanks for reporting this issue! > > I understand what you would like to see being visualized, but > unfortunately this is different from the implemented generic logic of > the visualization model that changes the color at the place of the > first event that belongs to the new task. Note that this generic logic > is expected to provide adequate visualization for all types of events, > while the behavior that you would like to see makes sense only for > very specific events. > > However, what you want is actually very easy to achieve. You just have > to write a kernelshark plugin for funcgraph_exit events. If you are > interested in contributing such plugin to kernelshark, I can send you > instructions what has to be done. It will be really trivial work. > > cheers, > Yordan > > > On 9/6/22 12:29, Matteo Bertolino wrote: >> Dear community, >> In order to explain my problem, I need to ask you to have a look to >> the visual trace in my github (I cannot attach it to the mail nor >> using an image uploading service): >> https://github.com/the-red-robin/trace-cmd-experiments/blob/main/READ >> ME.md >> >> In the trace, we have one CPU, CPU0. On it: >> - `Task3` runs `foo5()` at time 8.000000 cycles >> - `Task2` takes place running `foo3()` at time 8.010000 cycles. >> - `Task1` takes place running `foo1()` at time 8.060000 cycles. >> For now, everything OK. >> Then, I wish to `exit` the three tasks. >> >> - `Task1` exits at 8.090000 cycles. Here the trace does not show what I expect, namely `Task1` (in red) shall end at 8.090000 cycles. Instead, there is a red trace until the beginning of the next exit event, `Task2` at 8.130000. >> >> This doesn't seem an `exit` event. Do you have any suggestions to show what I wish on Kernelshark? >> >> Best Regards, >> Matteo
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