Messages in this thread | | | Date | Tue, 7 Sep 2010 17:32:58 +0530 | From | Srikar Dronamraju <> | Subject | Re: [PATCHv11 2.6.36-rc2-tip 5/15] 5: uprobes: Uprobes (un)registration and exception handling. |
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> On Mon, Sep 06, 2010 at 11:16:42PM +0530, Srikar Dronamraju wrote: > > > You don't have to, but you can. The problem I have with this stuff is > > > that it makes the pid thing a primary interface, whereas it should be > > > one of many filter possibilities. > > > > I think the otherway, > > Why instrument a process and filter it out, if we are not interested in it. > > While instrumenting kernel, we dont have this flexibility. So > > having a pid based filter is the right thing to do for kernel > > based tracing. > > > > If we can get the per process based tracing right, we can build > > higher lever stuff including the file based tracing easily. > > > > All tools/debuggers in the past have all worked with process based > > tracing. > > I have the feeling that you guys are at least partially talking past > each other. > > For the "perf probe --add" interface the only sane interface is one by > filename and then symbol / liner number / etc.
Agree, probing by file name is a requirement and I am working towards that end. > > But that is just the interface - these probes don't nessecarily have to > be armed and cause global overhead once they are define. If the > implenmentation is smart enough it will defer arming the probe until > we actually use it, and that will be per-process quite often.
Agree, That why I am trying to build file-based probing on pid-based probing.
> > Which btw, brings up two more issues, one in uprobes and one in perf. > For one even in userspace I think the dynamic probes will really just > be the tip of the iceberg and we'll get more bang for the buck from > static traces, which is something that's no supported in uprobes yet. > As a start supporting the dtrace-style sdt.h header would be a great > help, and then we can decide if we need somthing even better on top.
Yes, Static tracing using dtrace style sdt.h is a cool thing to do. Already SystemTap has this facility. However I think its probably better done at perf user interface level.
The way I look at it is perf probe decodes the static markers and asks uprobes to place probepoints over there. Do you see a different approach? If yes can you tell what you were looking at?
-- Thanks and Regards Srikar
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