Re: [PATCH 1/5] cfq-iosched: Do not idle if slice_idle=0

[Jeff Moyer <jmoyer@redhat.com>]

Vivek Goyal <vgoyal@redhat.com> writes:

> o do not idle either on cfq queue or service tree if slice_idle=0. User does
>   not want any queue or service tree idling. Currently even if slice_idle=0,
>   we were waiting for request to finish before expiring the queue and that
>   can lead to lower queue depths.

Hm, I submitted a similar patch that was supposed to make .35.  Oh well,

Acked-by: Jeff Moyer <jmoyer@redhat.com>

>
> Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> ---
>  block/cfq-iosched.c |    5 ++++-
>  1 files changed, 4 insertions(+), 1 deletions(-)
>
> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
> index eb4086f..8830569 100644
> --- a/block/cfq-iosched.c
> +++ b/block/cfq-iosched.c
> @@ -1839,6 +1839,9 @@ static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
>  	BUG_ON(!service_tree);
>  	BUG_ON(!service_tree->count);
>  
> +	if (!cfqd->cfq_slice_idle)
> +		return false;
> +
>  	/* We never do for idle class queues. */
>  	if (prio == IDLE_WORKLOAD)
>  		return false;
> @@ -1879,7 +1882,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
>  	/*
>  	 * idle is disabled, either manually or by past process history
>  	 */
> -	if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq))
> +	if (!cfq_should_idle(cfqd, cfqq))
>  		return;
>  
>  	/*