Messages in this thread | | | Date | Sun, 7 Apr 2002 20:32:46 +0100 | From | John Levon <> | Subject | Re: Two fixes for 2.4.19-pre5-ac3 |
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On Sun, Apr 07, 2002 at 08:42:48PM +0100, Alan Cox wrote:
> > I'll genuinely take on board advice on how I can profile all the system > > via x86 perf counters efficiently without having to patch the kernel. > > The old way just uses sys_call_table. So what do I do now ? > > The obvious thing is to represent it as a device. I'm not familiar enough > with the existing perfctr work to know how well that works out.
The system call tracking is only used to associate a particular EIP with a particular offset in some binary image. There's no other efficient method to capture the mmap() calls for these images, for everything running. ptrace() is only really useful for a small number of processes, and is slow. Offline post-analysis isn't possible. There is no API for getting access to this information.
Removing sys_call_table from exports won't have any positive effect. Using it has always been "well, you're on your own" - if there is a really good reason it needs to be changed, fine; but just changing it because it's not supposed to be used isn't a good enough reason when there is actually a couple of niche cases where it's the only option.
imho, john
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