Re: [PATCH] perf, p4: Add format attributes

[Peter Zijlstra <peterz@infradead.org>]

On Wed, 2012-03-28 at 02:03 +0400, Cyrill Gorcunov wrote:
> On Tue, Mar 27, 2012 at 07:12:50PM +0400, Cyrill Gorcunov wrote:
> > 
> > Ah, I see thanks for the reference, Peter!
> > 
> > > I've still not actually read the P4-PMU specs, so I don't know if
> > > there's anything more convenient we can do on P4. If there's a
> > > better/more useful format representation possible, don't hesitate to
> > > send a patch! :-)
> > 
> > Sure, I'll try to find some time tonight to read this brand
> > new stuff. And if I find something -- will send out. At moment
> > your patch should be more than enough ;)
> 
> Hi, Peter, sorry for delay,
> 
> after looking some more I think ht bit might be dropped from
> the format, it's used internally by the kernel in attmept to
> eliminate redundant msr poking if new event runs on the same
> thread as previous one, and it's always cleared before real
> write to msr happens, which means user-space might set or
> clear it, but it never be considered by the kernel.
> 
> (still my earlier reviewed-by is valid because this ht bit
>  is harmless ;)

So does that make escr:32-62 or should that become 32-63 ?