Date: Wed, 25 Mar 2009 17:17:00 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Ray Lee <ray-lk@madrabbit.org>
Cc: mingo@redhat.com, hpa@zytor.com, ego@in.ibm.com,
       linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl,
       dhaval@linux.vnet.ibm.com, balbir@in.ibm.com,
       bharata@linux.vnet.ibm.com, suresh.b.siddha@intel.com,
       tglx@linutronix.de, nickpiggin@yahoo.com.au, svaidy@linux.vnet.ibm.com,
       linux-tip-commits@vger.kernel.org
Subject: Re: [tip:sched/balancing] sched: Add comments to
	find_busiest_group() function
Message-ID: <20090325161700.GA1411@elte.hu>
References: <20090325091427.13992.18933.stgit@sofia.in.ibm.com> <tip-b7bb4c9bb01941fe8feb653f3410e7ed0c9bb786@git.kernel.org> <2c0942db0903250904x799271b5s78a1007d0fdbbb77@mail.gmail.com>
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* Ray Lee <ray-lk@madrabbit.org> wrote:

> This commit says it's just adding comments, but...
> 
> On Wed, Mar 25, 2009 at 5:30 AM, Gautham R Shenoy <ego@in.ibm.com> wrote:
> > Commit-ID: ?b7bb4c9bb01941fe8feb653f3410e7ed0c9bb786
> > Gitweb: ? ? http://git.kernel.org/tip/b7bb4c9bb01941fe8feb653f3410e7ed0c9bb786
> > Author: ? ? Gautham R Shenoy <ego@in.ibm.com>
> > AuthorDate: Wed, 25 Mar 2009 14:44:27 +0530
> > Committer: ?Ingo Molnar <mingo@elte.hu>
> > CommitDate: Wed, 25 Mar 2009 13:28:30 +0100
> >
> > sched: Add comments to find_busiest_group() function
> >
> > Impact: cleanup
> >
> > Add /** style comments around find_busiest_group(). Also add a few
> > explanatory comments.
> 
> ...but there are actual code changes. Hard to know if you intended to
> do that and forgot to changelog it, or if it's an unexpected hunk that
> accidentally got included:
> 
> > ? ? ? ?if (balance && !(*balance))
> > ? ? ? ? ? ? ? ?goto ret;
> >
> > - ? ? ? if (!sds.busiest || sds.this_load >= sds.max_load
> > - ? ? ? ? ? ? ? || sds.busiest_nr_running == 0)
> > + ? ? ? if (!sds.busiest || sds.busiest_nr_running == 0)
> > + ? ? ? ? ? ? ? goto out_balanced;
> > +
> > + ? ? ? if (sds.this_load >= sds.max_load)
> > ? ? ? ? ? ? ? ?goto out_balanced;
> >
> > ? ? ? ?sds.avg_load = (SCHED_LOAD_SCALE * sds.total_load) / sds.total_pwr;
> >
> > - ? ? ? if (sds.this_load >= sds.avg_load ||
> > - ? ? ? ? ? ? ? ? ? ? ? 100*sds.max_load <= sd->imbalance_pct * sds.this_load)
> > + ? ? ? if (sds.this_load >= sds.avg_load)
> > + ? ? ? ? ? ? ? goto out_balanced;
> > +
> > + ? ? ? if (100 * sds.max_load <= sd->imbalance_pct * sds.this_load)
> > ? ? ? ? ? ? ? ?goto out_balanced;
> >
> > ? ? ? ?sds.busiest_load_per_task /= sds.busiest_nr_running;

yeah.

Note that it does not actually change the resulting logic, it splits 
out an over-long (and hard to read) series of conditions into an 
equivalent set of two if() statements. [the first one changes the 
order of two conditions - but that is harmless]

It indeed would have been nice to declare this in the changelog 
though.

	Ingo
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