From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 22 Sep 2016 11:56:03 -0700 From: Christoph Hellwig To: Jens Axboe Cc: axboe@kernel.dk, linux-block@vger.kernel.org, jbacik@fb.com Subject: Re: [PATCH 1/2] blk-mq: get rid of manual run of queue with __blk_mq_run_hw_queue() Message-ID: <20160922185603.GA32468@infradead.org> References: <1474555980-2787-1-git-send-email-axboe@fb.com> <1474555980-2787-2-git-send-email-axboe@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1474555980-2787-2-git-send-email-axboe@fb.com> List-ID: Ok, I looked into this a bit more, and while I'm still fine with the patch I think it's only half of what we should do here. There really is no point in doing the first non-blocking path in blk_mq_map_request either as bt_get itself already does the non-blocking pass, and also runs the queue when scheduling in the later loop as well. So to get towards what I had in my tree we also need something like this: --- >>From c69bf02929d9c37d193b004a4c3c85c1142fa996 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 22 Sep 2016 11:38:23 -0700 Subject: blk-mq: remove non-blocking pass in blk_mq_map_request bt_get already does a non-blocking pass as well as running the queue when scheduling internally, no need to duplicate it. Signed-off-by: Christoph Hellwig --- block/blk-mq.c | 14 +------------- 1 file changed, 1 insertion(+), 13 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index eae2f12..e9ebe98 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1210,20 +1210,8 @@ static struct request *blk_mq_map_request(struct request_queue *q, op_flags |= REQ_SYNC; trace_block_getrq(q, bio, op); - blk_mq_set_alloc_data(&alloc_data, q, BLK_MQ_REQ_NOWAIT, ctx, hctx); + blk_mq_set_alloc_data(&alloc_data, q, 0, ctx, hctx); rq = __blk_mq_alloc_request(&alloc_data, op, op_flags); - if (unlikely(!rq)) { - blk_mq_run_hw_queue(hctx, false); - blk_mq_put_ctx(ctx); - trace_block_sleeprq(q, bio, op); - - ctx = blk_mq_get_ctx(q); - hctx = q->mq_ops->map_queue(q, ctx->cpu); - blk_mq_set_alloc_data(&alloc_data, q, 0, ctx, hctx); - rq = __blk_mq_alloc_request(&alloc_data, op, op_flags); - ctx = alloc_data.ctx; - hctx = alloc_data.hctx; - } hctx->queued++; data->hctx = hctx; -- 2.1.4