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Subject: Re: [announce] Performance Counters for Linux, v6
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org,
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Date: Fri, 20 Feb 2009 23:47:58 +0100
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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() ?