On 08/05/2013 11:49 AM, Steven Rostedt wrote:
> On Mon, 2013-08-05 at 11:29 -0700, H. Peter Anvin wrote:
>
>> Traps nest, that's why there is a stack. (OK, so you don't want to take
>> the same trap inside the trap handler, but that code should be very
>> limited.) The trap instruction just becomes very short, but rather
>> slow, call-return.
>>
>> However, when you consider the cost you have to consider that the
>> tracepoint is doing other work, so it may very well amortize out.
>
> Also, how would you pass the parameters? Every tracepoint has its own
> parameters to pass to it. How would a trap know what where to get "prev"
> and "next"?
>
How do you do that now?
You have to do an IP lookup to find out what you are doing.
(Note: I wonder how much the parameter generation costs the tracepoints.)
-hpa
