Re: [announce] Performance Counters for Linux, v6

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

Peter Zijlstra wrote:
> On Fri, 2009-02-20 at 14:38 -0800, Corey Ashford wrote:
>> There may be other non-event-related changes that will not be handled 
>> quite as well in this way.  In the original email I hinted at that we 
>> may want an option for mmap'd sample buffers at some point, and so I'm 
>> not clear how you'd provide an ABI to request mmap'd buffers (you would 
>> probably need to be able to request the size and get back a pointer to 
>> the mmap'd buffer).  Would this be done through a special 
>> sys_perf_counter_open call?  Or through a subsequent ioctl call on the 
>> group leader after an open (which requires the counters to be initially 
>> disabled), etc.
> 
> What's stopping a regular mmap() call using the fd obtained from
> sys_perf_counter_open() ?

Perhaps nothing.  I don't know why it didn't occur to me that this could 
be done.  If PCL supports this, great!

Thanks for your reply!

-- 
Regards,

- Corey

Corey Ashford
Software Engineer
IBM Linux Technology Center, Linux Toolchain
Beaverton, OR
503-578-3507
cjashfor@us.ibm.com