linux-kernel - Re: [PATCH 11/24] io-controller: Introduce group idling

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Date:	Fri, 28 Aug 2009 09:12:57 +0800
From:	Gui Jianfeng <guijianfeng@...fujitsu.com>
To:	Vivek Goyal <vgoyal@...hat.com>
CC:	linux-kernel@...r.kernel.org,
	containers@...ts.linux-foundation.org, dm-devel@...hat.com,
	jens.axboe@...cle.com, ryov@...inux.co.jp,
	balbir@...ux.vnet.ibm.com, righi.andrea@...il.com,
	nauman@...gle.com, dpshah@...gle.com, lizf@...fujitsu.com,
	mikew@...gle.com, fchecconi@...il.com, paolo.valente@...more.it,
	fernando@....ntt.co.jp, s-uchida@...jp.nec.com, taka@...inux.co.jp,
	jmoyer@...hat.com, dhaval@...ux.vnet.ibm.com,
	m-ikeda@...jp.nec.com, agk@...hat.com, akpm@...ux-foundation.org,
	peterz@...radead.org, jmarchan@...hat.com
Subject: Re: [PATCH 11/24] io-controller: Introduce group idling

Vivek Goyal wrote:
...
> @@ -2201,13 +2362,44 @@ void elv_ioq_completed_request(struct request_queue *q, struct request *rq)
>  		 * mean seek distance, give them a chance to run instead
>  		 * of idling.
>  		 */
> -		if (elv_ioq_slice_used(ioq) || elv_ioq_class_idle(ioq))
> +		if (elv_ioq_slice_used(ioq) || elv_ioq_class_idle(ioq)) {
> +			/*
> +			 * This is the last empty queue in the group and it
> +			 * has consumed its slice. If we expire it right away
> +			 * group might loose its share. Wait for an extra
> +			 * group_idle period for a request before queue
> +			 * expires.
> +			 */
> +			if (elv_iog_should_idle(ioq)) {
> +				elv_iog_arm_slice_timer(q, iog, 1);
> +				goto done;
> +			}
> +

Hi Vivek,

I think we shouldn't arm idle timer on iog again, if it's already on.

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

diff --git a/block/elevator-fq.c b/block/elevator-fq.c
index a4161c2..04f646f 100644
--- a/block/elevator-fq.c
+++ b/block/elevator-fq.c
@@ -3116,7 +3116,8 @@ void elv_ioq_completed_request(struct request_queue *q, struct request *rq)
 			 * group_idle period for a request before queue
 			 * expires.
 			 */
-			if (elv_iog_should_idle(ioq)) {
+			if (elv_iog_should_idle(ioq) &&
+			    !elv_iog_wait_busy(iog)) {
 				elv_iog_arm_slice_timer(q, iog, 1);
 				goto done;
 			}
-- 
1.5.4.rc3



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