Frank Ch. Eigler wrote: > Hi - > >>> As you might expect, in systemtap we've had to figure out this area >>> some time ago. We use another utrace consumer called "task finder" [...] >> >> So, could you tell us how the task-finder works and is implemented? > > The code may be found at runtime/task_finder* in the systemtap sources. > There is a simple interest-registration structure/API that identifies > processes / shared libraries of interest, and a set of callbacks to be > invoked when said processes/shared libraries are mapped or unmapped. > > It is implemented in terms of utrace callbacks for process/thread > lifetime monitoring, and utrace syscall callbacks for tracking shared > library segments being mapped and unmapped. > > http://sourceware.org/git/?p=systemtap.git;a=tree;f=runtime
Nice! so we can set a probe by the relative address in the library segments. >> I think we'd better clarify what functions are required for uprobes >> and pmu, and I think we may be able to re-implement improved pmu on >> utrace. > > I don't see any collision between pmu / perf / utrace, so nothing is > really "required" for them or simple usage of uprobes. If you wish to > track dynamic process/shared-library lifetimes, then you need extra > code somewhere to respond to those changes. And that code we can find in runtime/task_finder*, right? :-) > Layering this dynamic > capability seems like the natural way to go, and is easily done with > utrace and/or tracepoints. Sure, and I think that will allow us to use uprobe events as trace-events, because we can set probes before executing programs. :-) Thank you! -- Masami Hiramatsu Software Engineer Hitachi Computer Products (America), Inc. Software Solutions Division e-mail: mhira...@redhat.com
