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Date: Fri, 28 May 2010 17:57:20 +0200
From: Borislav Petkov <bp@amd64.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>, Borislav Petkov <bp@alien8.de>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       Steven Rostedt <rostedt@goodmis.org>,
       Arnaldo Carvalho de Melo <acme@redhat.com>,
       Lin Ming <ming.m.lin@intel.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] perf: Add persistent events
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From: Peter Zijlstra <peterz@infradead.org>
Date: Fri, May 28, 2010 at 05:17:40PM +0200

> On Fri, 2010-05-28 at 16:33 +0200, Ingo Molnar wrote:
> 
> > >  2) get these things a buffer, perf_events as created don't actually
> > >     have an output buffer, normally that is created at mmap() time, but
> > >     since you cannot mmap() a kernel side event, it doesn't get to have
> > >     a buffer. This could be done by extracting perf_mmap_data_alloc()
> > >     into a sensible interface.
> > 
> > #2 could be a new syscall: sys_create_ring_buffer or so?
> 
> No, they need a buffer in-kernel, syscalls aren't the ideal tool for
> that :-)

Yeah, I need a per-cpu buffer ready at event registration/enable time,
maybe even have perf_event_create_kernel_counter() take care of that
buffer allocation with a flag or similar prior to enabling the event...

> I've got patches refactoring the whole buffer stuff to make it more a
> self-contained entity.

Can I see those when you're done so that I can base my stuff on top?

Thanks.

-- 
Regards/Gruss,
Boris.

Operating Systems Research Center
Advanced Micro Devices, Inc.