Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755745Ab1C3KQQ (ORCPT ); Wed, 30 Mar 2011 06:16:16 -0400 Received: from 0122700014.0.fullrate.dk ([95.166.99.235]:48607 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754925Ab1C3KQO (ORCPT ); Wed, 30 Mar 2011 06:16:14 -0400 Message-ID: <4D9302ED.4030807@kernel.dk> Date: Wed, 30 Mar 2011 12:16:13 +0200 From: Jens Axboe MIME-Version: 1.0 To: Tejun Heo CC: Vivek Goyal , Jeff Moyer , Mike Snitzer , Markus Trippelsdorf , Sergey Senozhatsky , linux-kernel@vger.kernel.org, Chris Mason Subject: Re: [PATCH] block: eliminate ELEVATOR_INSERT_REQUEUE References: <20110325185455.GA2969@redhat.com> <4D8CF202.9010809@kernel.dk> <20110326042156.GB28458@redhat.com> <20110328082321.GC16530@htj.dyndns.org> <20110328221547.GA1118@redhat.com> <20110329175458.GE24485@redhat.com> <20110330074123.GA17523@htj.dyndns.org> <20110330075752.GC17523@htj.dyndns.org> <4D92E2CD.6000909@kernel.dk> <20110330080203.GD17523@htj.dyndns.org> In-Reply-To: <20110330080203.GD17523@htj.dyndns.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4863 Lines: 135 On 2011-03-30 10:02, Tejun Heo wrote: > Hello, Jens. > > On Wed, Mar 30, 2011 at 09:59:09AM +0200, Jens Axboe wrote: >> Pure front insert should be used for requeue and internal commands (like >> spin up this drive, or get error information). Flush should append to >> the dispatch list. > > Yeah, right. The reason I used REQUEUE/FRONT was because BACK > insertion involves draining the elevator and then appending the > request at the end of the dispatch queue, which is unnecessary and > inefficient. So, front insertion was a quick work around that. If > we're removing elv_insert(), we can just append directly to the > dispatch queue from flush code. How does this look? It's really two patches, but rolled up into one for easier posting here. diff --git a/block/blk-flush.c b/block/blk-flush.c index 93d5fd8..6a16fea 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -261,7 +261,7 @@ static bool blk_kick_flush(struct request_queue *q) q->flush_rq.end_io = flush_end_io; q->flush_pending_idx ^= 1; - elv_insert(q, &q->flush_rq, ELEVATOR_INSERT_REQUEUE); + __elv_add_request(q, &q->flush_rq, ELEVATOR_INSERT_FLUSH); return true; } @@ -281,7 +281,7 @@ static void flush_data_end_io(struct request *rq, int error) * blk_insert_flush - insert a new FLUSH/FUA request * @rq: request to insert * - * To be called from elv_insert() for %ELEVATOR_INSERT_FLUSH insertions. + * To be called from __elv_add_request() for %ELEVATOR_INSERT_FLUSH insertions. * @rq is being submitted. Analyze what needs to be done and put it on the * right queue. * @@ -312,7 +312,7 @@ void blk_insert_flush(struct request *rq) */ if ((policy & REQ_FSEQ_DATA) && !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) { - list_add(&rq->queuelist, &q->queue_head); + list_add_tail(&rq->queuelist, &q->queue_head); return; } diff --git a/block/elevator.c b/block/elevator.c index c387d31..0cdb4e7 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -610,7 +610,7 @@ void elv_requeue_request(struct request_queue *q, struct request *rq) rq->cmd_flags &= ~REQ_STARTED; - elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); + __elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE); } void elv_drain_elevator(struct request_queue *q) @@ -655,12 +655,25 @@ void elv_quiesce_end(struct request_queue *q) queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); } -void elv_insert(struct request_queue *q, struct request *rq, int where) +void __elv_add_request(struct request_queue *q, struct request *rq, int where) { trace_block_rq_insert(q, rq); rq->q = q; + BUG_ON(rq->cmd_flags & REQ_ON_PLUG); + + if (rq->cmd_flags & REQ_SOFTBARRIER) { + /* barriers are scheduling boundary, update end_sector */ + if (rq->cmd_type == REQ_TYPE_FS || + (rq->cmd_flags & REQ_DISCARD)) { + q->end_sector = rq_end_sector(rq); + q->boundary_rq = rq; + } + } else if (!(rq->cmd_flags & REQ_ELVPRIV) && + where == ELEVATOR_INSERT_SORT) + where = ELEVATOR_INSERT_BACK; + switch (where) { case ELEVATOR_INSERT_REQUEUE: case ELEVATOR_INSERT_FRONT: @@ -722,24 +735,6 @@ void elv_insert(struct request_queue *q, struct request *rq, int where) BUG(); } } - -void __elv_add_request(struct request_queue *q, struct request *rq, int where) -{ - BUG_ON(rq->cmd_flags & REQ_ON_PLUG); - - if (rq->cmd_flags & REQ_SOFTBARRIER) { - /* barriers are scheduling boundary, update end_sector */ - if (rq->cmd_type == REQ_TYPE_FS || - (rq->cmd_flags & REQ_DISCARD)) { - q->end_sector = rq_end_sector(rq); - q->boundary_rq = rq; - } - } else if (!(rq->cmd_flags & REQ_ELVPRIV) && - where == ELEVATOR_INSERT_SORT) - where = ELEVATOR_INSERT_BACK; - - elv_insert(q, rq, where); -} EXPORT_SYMBOL(__elv_add_request); void elv_add_request(struct request_queue *q, struct request *rq, int where) diff --git a/include/linux/elevator.h b/include/linux/elevator.h index d93efcc445..21a8ebf 100644 --- a/include/linux/elevator.h +++ b/include/linux/elevator.h @@ -101,7 +101,6 @@ extern void elv_dispatch_sort(struct request_queue *, struct request *); extern void elv_dispatch_add_tail(struct request_queue *, struct request *); extern void elv_add_request(struct request_queue *, struct request *, int); extern void __elv_add_request(struct request_queue *, struct request *, int); -extern void elv_insert(struct request_queue *, struct request *, int); extern int elv_merge(struct request_queue *, struct request **, struct bio *); extern int elv_try_merge(struct request *, struct bio *); extern void elv_merge_requests(struct request_queue *, struct request *, -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/