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Date: Thu, 31 Aug 2017 13:43:27 -0300
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>, kan.liang@intel.com,
        mingo@redhat.com, linux-kernel@vger.kernel.org, jolsa@redhat.com,
        tglx@linutronix.de, eranian@google.com, ak@linux.intel.com,
        mpe@ellerman.id.au
Subject: Re: [PATCH V8] perf: Add PERF_SAMPLE_PHYS_ADDR
Message-ID: <20170831164327.GI4831@kernel.org>
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Em Tue, Aug 29, 2017 at 01:45:53PM +0200, Peter Zijlstra escreveu:
> On Tue, Aug 29, 2017 at 05:05:15PM +0530, Madhavan Srinivasan wrote:
> > 
> > 
> > On Tuesday 29 August 2017 06:22 AM, kan.liang@intel.com wrote:
> > > From: Kan Liang <kan.liang@intel.com>
> > > 
> > > For understanding how the workload maps to memory channels and hardware
> > > behavior, it's very important to collect address maps with physical
> > > addresses. For example, 3D XPoint access can only be found by filtering
> > > the physical address.
> > > 
> > > Add a new sample type for physical address.
> > > 
> > > perf already has a facility to collect data virtual address. This patch
> > > introduces a function to convert the virtual address to physical address.
> > > The function is quite generic and can be extended to any architecture as
> > > long as a virtual address is provided.
> > >   - For kernel direct mapping addresses, virt_to_phys is used to convert
> > >     the virtual addresses to physical address.
> > >   - For user virtual addresses, __get_user_pages_fast is used to walk the
> > >     pages tables for user physical address.
> > >   - This does not work for vmalloc addresses right now. These are not
> > >     resolved, but code to do that could be added.
> > > 
> > > The new sample type requires collecting the virtual address. The
> > > virtual address will not be output unless SAMPLE_ADDR is applied.
> > > 
> > > For security, the physical address can only be exposed to root or
> > > privileged user.
> > 
> > Tested-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>

You mean you tested this together with Kan's v2 perf tools patches? If
that is so I'll add this tested-by to those patches, ok?
 
> Thanks maddy!