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Hi - Vara wrote: > [...] The main idea of a tapset as i see is, an expert in a given > subsystem knows what is important to understand the inner workings > of that subsystem. That expert will export such vital data in the > form of a tapset using one or more functions that can be called from > a probe. [...] Tapsets just like probes can be either PC based or > asynchronous timer based. [...] So far, it sounds like your concept of "tapsets" could be subsumed into the script library idea. Specifically, a domain expert could write some systemtap script fragments, as opposed to new C code that somehow needs to find its way into the kernel. Library script fragments would contain ordinary systemtap constructs to define probes, functions, global variables needed to instrument a target domain. Each probe would use an already supported probe-point syntax to identify a PC breakpoint or some other known event source. Communication with the user-specified script would take place through the globals and perhaps functions. For example, a probe script fragment that specializes in the scheduler could maintain a couple of global lookup tables that represent current state in a higher-level way: like a list of currently running processes, their cumulative run times, etc. A user script referring to these globals would automagically cause the related probes to be activated. We may encounter probe domains where the then-existing PC- or event-based probe insertion APIs will not be not enough. When that time comes, I expect we will need to extend the systemtap translator to support new probe-point constructs to refer to them. It would be great if someone could work out an example or two to see whether the idea of a script fragment library is or is not sufficient to express interesting cases. - FChE
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