On Sun, Sep 29, 2002 at 04:29:14AM +0200, Andi Kleen wrote:
> Can you explain what you need the context switch hook for ?
Hmm, I tried to explain this in comments in the patch ...
> I don't think it's a good idea to put a hook at such a critical place.
... but I obviously didn't do a very good job.
We need a context to look up the EIP against when we process each sample
in buffer_sync.c. We could just log current at sample time along with
EIP/event, but why would it be preferrable to just logging the same
information once when it's needed ?
Basically it's a matter of :
task_struct *
EIP/Event
EIP/Event
EIP/Event
EIP/Event
....
versus
task_struct */EIP/Event
task_struct */EIP/Event
task_struct */EIP/Event
task_struct */EIP/Event
task_struct */EIP/Event
....
Where task_struct is the same as the previous entry for the vast
majority of entries.
> 2.4 oprofile worked without such a hook, no ?
Sure, but it was ugly as hell (and worked completely differently)
regards
john
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