Messages in this thread | | | Date | Tue, 08 Aug 2006 18:28:28 +0100 | From | Paulo Marques <> | Subject | Re: [PATCH 1/3] Kprobes: Make kprobe modules more portable |
| |
Christoph Hellwig wrote: > On Tue, Aug 08, 2006 at 09:34:00AM -0700, Stephen Hemminger wrote: >> Okay, does this makes kprobe's the first reflective kernel interface. > > Actually kallsyms_lookup_name was the first interface like that. And lots > of external kprobes used it like that - in fact tcp_probe.c is the first > one I've seen doing it differently. But kallsyms_lookup_name is a really > awkward lowlevel buildingblock that's almost impossible to use correctly, > so this patch hides it behind the proper kprobes interface.
Just one side note: kallsyms_lookup_name is _really_ inefficient. The kallsyms structure is tailored so that kallsyms_lookup (the most frequently used function) is really fast. Doing it the other way around involves a O(N) search, uncompressing every symbol name as it goes :P
I don't think this is really a performance problem for users like kprobes, but I just wanted people to keep in mind that there is a penalty involved in calling kallsyms_lookup_name.
-- Paulo Marques - www.grupopie.com
"The face of a child can say it all, especially the mouth part of the face." - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |