On 1/28/08, Andrew Morton <[EMAIL PROTECTED]> wrote: > Neither the changelog nor the newly-added documentation explain why Linux > needs this feature. What will it be used for??
There's a detailed discussion along with an example on this thread: http://lkml.org/lkml/2007/11/13/58 and a bit on: http://sourceware.org/ml/systemtap/2005-q3/msg00593.html The real advantage of this patch is in scenarios where some data (like function paramters, system time etc) needs to be shared between function entry and exit. E.g: Viewing the change in system time across a call to profile it. Here, we have a need to share data between the entry and exit events of a function call. Also, the correct association needs to be maintained between the corresponding function entry-exit pairs. This is already done using a 'return-instance' in kretprobes. This patch allows these instances to pouch some data as well. The patch also has a module example which does trivial function time-duration profiling using entry-handlers. It makes writing function profilers simpler using kretprobes. Currently, doing such a thing would require an extra kprobe to be planted at function entry-point and whose pre-handler must have all the complexity to do the function entry-exit data association. Also, using an entry-handler is optional, and is completely backward compatible. > > +1.3.2 Kretprobe entry-handler > > + > > +Kretprobes also provides an optional user-specified handler which runs > > I think "caller-specified" would be a better term here. Generally "user" > refers to Aunt Tillie sitting at the keyboard. Just followed suit from exising kprobes.txt which had quite a few references to such a 'user'. Cheerfully Acked by -> Aunt Tillie :-) -- Thanks, Abhishek -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/