Messages in this thread | | | Date | Fri, 18 Jan 2008 15:20:21 -0800 | From | Arjan van de Ven <> | Subject | Re: [patch 2/3] Latencytop instrumentations part 1 |
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Frank Ch. Eigler wrote: > Hi - > > On Fri, Jan 18, 2008 at 02:33:34PM -0800, Arjan van de Ven wrote: >> [...] >>> Can you suggest of some reason why all this instrumentation could >>> not be in the form of standard markers (perhaps conditionally >>> compiled out if necessary)? >> sure. Every instrumentation you see is of the nested kind (since the lowest level >> of nesting is already automatic via wchan). >> If markers can provide me the following semantics, I'd be MORE than happy to use markers: >> [...] >> If markers can provide that semantics ... you sold me. > > Further to what acme said, markers are semantics-free. Callback > functions that implement your entry & exit semantics can be attached > at run time, at your pleasure. (So can systemtap probes, for that > matter.) The main difference would be that these callback functions > would have manage the per-thread LIFO data structures themselves, > instead of allocating backpointers on the kernel stack. (Bonus marks > for not modifying task_struct. :-)
modifying task struct to have storage space is no big deal...
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