Re: [PATCH 1/6] perf_counter: move the event overflow output bits to record_type

[Corey Ashford <cjashfor@linux.vnet.ibm.com>]

Peter Zijlstra wrote:
> On Thu, 2009-04-02 at 16:27 -0700, Corey Ashford wrote:
>> Whoops, nevermind.
>>
>> My misunderstanding on this one.  This enum is used for event type, not 
>> the record_type, and as such is makes sense for there to be exclusive 
>> mmap and munmap event records.
>>
>> Thinking about this a bit, I'm guessing that the idea is to track the 
>> loading and unloading of shared objects which uses mmap and munmap, so 
>> that that the ip can be related to a particular object that was mapped 
>> in at the time of the counter overflow interrupt.  Is that right?
> 
> Indeed, whenever a mmap/munmap happens of a PROT_EXEC range we record
> that information so that we can relate the userspace IPs to some file
> and hence the actual userspace code.

Ah, I see, PROT_EXEC identifies the executable code sections in particular.

Thanks :-)

- Corey