[lttng-dev] Need help: Kernel tracer not available and can't find the lttng-probe-latency_tracker

[Kienan Stewart]

Hi Tao,

due to lack of financing, the latency_tracker project 
(https://github.com/efficios/latency-tracker/) isn't being actively 
maintained at this time.

Another option to get information on event latencies is to have 
"_entry"- and "_exit"-style events and perform post-processing of the 
traces with the Trace Compass Incubator "inandout" plugin.

https://git.eclipse.org/r/plugins/gitiles/tracecompass.incubator/org.eclipse.tracecompass.incubator/+/refs/heads/master/doc/org.eclipse.tracecompass.incubator.inandout.doc.user/doc/User-Guide.mediawiki

On 2023-10-25 02:41, 姜涛 Tao(AD) via lttng-dev wrote:
> Hi everyone, I have read this blog: 
> https://lttng.org/blog/2016/01/06/monitoring-realtime-latencies/ 
> <https://lttng.org/blog/2016/01/06/monitoring-realtime-latencies/>, and 
> I think latency_tracker project will be very useful in resovling my 
> problem under linux rt patch kernel 5.10, but it doesn't support linux 
> newer kernel, so I find the span-latency-tracker project later. But when 
> I use lttng create session，I get the error :
> Error: Event wakeup_latency: Kernel tracer not available (channel 
> channel0, session auto-20231024-134242)
> Error: Event block_latency: Kernel tracer not available (channel 
> channel0, session auto-20231024-134242)
> 
> 文本 描述已自动生成
> 
> And I find this tip: "To use the tracepoints provided by this module 
> with LTTng, you first have to connect LTTng probes to them. A patch 
> ready to be applied to the last lttng-modules is provided in extras/ 
> <https://github.com/adel-belkhiri/span-latency-tracker/blob/master/extras>. When installed, compiled, load the new probe module with modprobe lttng-probe-latency_tracker", but I can't find the "lttng-probe-latency_tracker" module in the lttng-module compiled modules or in the span-latency-tracker compiled modules.

This appears to be a fork of the latency_tracker project. We're not in a 
position to offer support for any changes that have been made there.

> 
> I also create the issue on the github: 
> https://github.com/adel-belkhiri/span-latency-tracker/issues/1 
> <https://github.com/adel-belkhiri/span-latency-tracker/issues/1>.
> Any help will be appreciated! Thanks!
> 
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thanks,
kienan