Re: [RFC PATCH 11/11] sched: Add comments to find_busiest_group()function.

From: Ingo Molnar
Date: Wed Mar 25 2009 - 08:29:36 EST



* Gautham R Shenoy <ego@xxxxxxxxxx> wrote:

> On Wed, Mar 25, 2009 at 02:44:27PM +0530, Gautham R Shenoy wrote:
> > Add /** style comments around find_busiest_group(). Also add a few explanatory
> > */
>
> <snip>
>
> > static struct sched_group *
> > find_busiest_group(struct sched_domain *sd, int this_cpu,
> > @@ -3593,17 +3613,31 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
> > update_sd_lb_stats(sd, this_cpu, idle, sd_idle, cpus,
> > balance, &sds);
> >
> > + /* Cases where imbalance does not exist from POV of this_cpu */
> > + /* 1) this_cpu is not the appropriate cpu to perform load balancing
> > + * at this level.
> > + * 2) There is no busy sibling group to pull from.
> > + * 3) This group is the busiest group.
> > + * 4) This group is more busy than the avg busieness at this
> > + * sched_domain.
> > + * 5) The imbalance is within the specified limit.
> > + * 6) Any rebalance would lead to ping-pong
> > + */
> > if (balance && !(*balance))
> > goto ret;
> >
> > - if (!sds.busiest || sds.this_load >= sds.max_load
> > - || sds.busiest_nr_running == 0)
> > + if (!sds.busiest || sd.busiest_nr_running == 0)
> ^^^^^^^^^^^^^^^^^^^^
> should have been sds.busiest_nr_running. Hence the build failure on tip.
>
> I think I missed compile testing this last patch.
>
> Ingo, could you revert commit 7b6340ef884aff69a54f8a530c73ad9da0a7c388 in
> tip/balancing and commit the following patch instead?

sure - i've amended it and started testing it locally. If it passes
testing it should show up in tip:master.

Ingo
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