Re: [PATCH v4 06/11] sched/fair: use load instead of runnable load in load_balance

[Mel Gorman]

On Fri, Oct 18, 2019 at 03:26:33PM +0200, Vincent Guittot wrote:
> runnable load has been introduced to take into account the case
> where blocked load biases the load balance decision which was selecting
> underutilized group with huge blocked load whereas other groups were
> overloaded.
> 
> The load is now only used when groups are overloaded. In this case,
> it's worth being conservative and taking into account the sleeping
> tasks that might wakeup on the cpu.
> 
> Signed-off-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>

Hmm.... ok. Superficially I get what you're doing but worry slightly
about groups that have lots of tasks that are frequently idling on short
periods of IO.

Unfortuntely when I queued this series for testing I did not queue a load
that idles rapidly for short durations that would highlight problems in
that area.

I cannot convince myself it's ok enough for an ack but I have no reason
to complain either.

-- 
Mel Gorman
SUSE Labs