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Subject: Re: [RFC][PATCH 3/9] perf: export registerred pmus via sysfs
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To: Will Deacon <will.deacon@arm.com>
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Date: Tue, 11 May 2010 08:34:54 +0200
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On Mon, 2010-05-10 at 21:25 +0100, Will Deacon wrote:
> Another interesting ARM-ism is the vast potential for uncore event
> sources in SoC devices. The `node' terminology seems a bit confusing
> here, as there may be counters situated at various points of a bus
> hierarchy which monitor various types of transactions for example. I
> suppose these could live under /sys/devices/system/bus/... ?

Right there are more such systems, and yes hooking them into the
appropriate machine topology like PCI busses is exactly the intent.

I already mentioned the GPU PMUs living in the appropriate PCI device.
But yes, there are far more exotic configurations out there.

>  I would
> expect these kind of counters to be controlled via raw events because
> having a list of discrete events doesn't really make sense [for example,
> if I want to count all bursts of a given size, I can encode the burst
> size into the event number]. 

Raw is fine, its only once these things start to converge and show
common traits that adding a 'generic' event class becomes useful, and
this is something that can always be done later.