Re: [PATCH 1/2] tools, perf: Add a precise event qualifier v2

[Vince Weaver]

On Wed, 24 Jul 2013, Andi Kleen wrote:

> Sorry I meant flags as an alias of "the 64bits currently occupied by the
> bitfield". Perhaps the name choice was not very good.
> 
> "flags_bitfield" ?
> 
> So the tool would only need to know that, not every bit.
> 
> In theory it could be also generalized as a byte offset to perf_event,
> but that may be overengineered.

I somehow doubt this would be acceptable.  If it were, we could have had a 
somewhat better interface by just having the event fields be a list of 
values without involving format/* at all, something like

   config=0x58034;config1=0x20;precise_ip=0x4

For whatever reason things have to be human readable, and I don't think
just having an opaque 64-bit "flags" value will be accepted.  

I'm likely wrong though, I have a very low accuracy rate for predicting 
future perf_event design decisions.

This is all complicated by the intertwined nature of the perf_event ABI 
and the perf tool, and the way that there's at least three or four 
different ways to specify the same event from the perf tool command line.

Vince
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