[dm-devel] Re: [PATCH 22/24] io-controller: Per io group bdi congestion interface

[Gui Jianfeng]

Vivek Goyal wrote:
...
> +/* Set io group congestion on and off thresholds */
> +void elv_io_group_congestion_threshold(struct request_queue *q,
> +						struct io_group *iog)
> +{
> +	int nr;
> +
> +	nr = q->nr_group_requests - (q->nr_group_requests / 8) + 1;
> +	if (nr > q->nr_group_requests)
> +		nr = q->nr_group_requests;
> +	iog->nr_congestion_on = nr;
> +
> +	nr = q->nr_group_requests - (q->nr_group_requests / 8)
> +			- (q->nr_group_requests / 16) - 1;
> +	if (nr < 1)
> +		nr = 1;
> +	iog->nr_congestion_off = nr;

Vivek,

Since we determine whether io group is congenssed or not just by checking 
iog->nr_congestion_on, we can get rid of iog->nr_congestion_off here.

Signed-off-by: Gui Jianfeng <guijianfeng at cn.fujitsu.com>
---
 block/elevator-fq.c |    6 ------
 block/elevator-fq.h |    3 +--
 2 files changed, 1 insertions(+), 8 deletions(-)

diff --git a/block/elevator-fq.c b/block/elevator-fq.c
index 66b10eb..e73da31 100644
--- a/block/elevator-fq.c
+++ b/block/elevator-fq.c
@@ -1267,12 +1267,6 @@ void elv_io_group_congestion_threshold(struct request_queue *q,
 	if (nr > q->nr_group_requests)
 		nr = q->nr_group_requests;
 	iog->nr_congestion_on = nr;
-
-	nr = q->nr_group_requests - (q->nr_group_requests / 8)
-			- (q->nr_group_requests / 16) - 1;
-	if (nr < 1)
-		nr = 1;
-	iog->nr_congestion_off = nr;
 }
 
 static inline int elv_is_iog_congested(struct request_queue *q,
diff --git a/block/elevator-fq.h b/block/elevator-fq.h
index 0581e55..2815279 100644
--- a/block/elevator-fq.h
+++ b/block/elevator-fq.h
@@ -266,9 +266,8 @@ struct io_group {
 	/* Single ioq per group, used for noop, deadline, anticipatory */
 	struct io_queue *ioq;
 
-	/* io group congestion on and off threshold for request descriptors */
+	/* io group congestion on threshold for request descriptors */
 	unsigned int nr_congestion_on;
-	unsigned int nr_congestion_off;
 
 	/* request list associated with the group */
 	struct request_list rl;
-- 
1.5.4.rc3