linux-kernel - Re: [RFC][PATCH 10/14] x86: generic aperf/mperf code.

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Date:	Fri, 4 Sep 2009 10:22:12 -0400
From:	Dave Jones <davej@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Thomas Renninger <trenn@...e.de>, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org, Gautham R Shenoy <ego@...ibm.com>,
	Andreas Herrmann <andreas.herrmann3@....com>,
	Balbir Singh <balbir@...ibm.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>,
	Yanmin <yanmin_zhang@...ux.intel.com>,
	Len Brown <len.brown@...el.com>,
	Yinghai Lu <yhlu.kernel@...il.com>, cpufreq@...r.kernel.org
Subject: Re: [RFC][PATCH 10/14] x86: generic aperf/mperf code.

On Fri, Sep 04, 2009 at 11:27:19AM +0200, Peter Zijlstra wrote:
 > On Fri, 2009-09-04 at 11:25 +0200, Peter Zijlstra wrote:
 > > On Fri, 2009-09-04 at 11:19 +0200, Thomas Renninger wrote:
 > > > You still use struct perf_pair split/hi/lo members in #ifdef __i386__ 
 > > > case which you deleted above.
 > > 
 > > > >               shift_count = fls(h);
 > > > >  
 > > > > -             cur.aperf.whole >>= shift_count;
 > > > > -             cur.mperf.whole >>= shift_count;
 > > > > +             cur.aperf >>= shift_count;
 > > > > +             cur.mperf >>= shift_count;
 > > > >       }
 > > > >  
 > > > >       if (((unsigned long)(-1) / 100) < cur.aperf.split.lo) {
 > > > Same here, possibly still elsewhere.
 > > > Is this only x86_64 compile tested?
 > > 
 > > Of course, who still has 32bit only hardware anyway ;-)
 > > 
 > > Will fix, thanks for spotting that.
 > 
 > Hrmm, on that, does it really make sense to maintain the i386 code path?
 > 
 > How frequently is that code called and what i386 only chips support
 > aperf/mperf, atom?

any 64-bit cpu that supports it can have a 32bit kernel installed on it.
(and a significant number of users actually do this).

	Dave
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