Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933596AbXHHKRt (ORCPT ); Wed, 8 Aug 2007 06:17:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751128AbXHHKRh (ORCPT ); Wed, 8 Aug 2007 06:17:37 -0400 Received: from relay.2ka.mipt.ru ([194.85.82.65]:47928 "EHLO 2ka.mipt.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751145AbXHHKRe (ORCPT ); Wed, 8 Aug 2007 06:17:34 -0400 Date: Wed, 8 Aug 2007 14:17:09 +0400 From: Evgeniy Polyakov To: Jens Axboe Cc: Daniel Phillips , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Peter Zijlstra Subject: [1/1] Block device throttling [Re: Distributed storage.] Message-ID: <20070808101708.GA23815@2ka.mipt.ru> References: <20070731171347.GA14267@2ka.mipt.ru> <200708051423.45484.phillips@phunq.net> <20070807120523.GX5245@kernel.dk> <200708071124.56859.phillips@phunq.net> <20070807205538.GB5245@kernel.dk> <20070808095448.GA3440@2ka.mipt.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070808095448.GA3440@2ka.mipt.ru> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3456 Lines: 123 This throttling mechanism allows to limit maximum amount of queued bios per physical device. By default it is turned off and old block layer behaviour with unlimited number of bios is used. When turned on (queue limit is set to something different than -1U via blk_set_queue_limit()), generic_make_request() will sleep until there is room in the queue. number of bios is increased in generic_make_request() and reduced either in bio_endio(), when bio is completely processed (bi_size is zero), and recharged from original queue when new device is assigned to bio via blk_set_bdev(). All oerations are not atomic, since we do not care about precise number of bios, but a fact, that we are close or close enough to the limit. Tested on distributed storage device - with limit of 2 bios it works slow :) Signed-off-by: Evgeniy Polyakov diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c index c99b463..1882c9b 100644 --- a/block/ll_rw_blk.c +++ b/block/ll_rw_blk.c @@ -1851,6 +1851,10 @@ request_queue_t *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug; q->backing_dev_info.unplug_io_data = q; + q->bio_limit = -1U; + q->bio_queued = 0; + init_waitqueue_head(&q->wait); + mutex_init(&q->sysfs_lock); return q; @@ -3237,6 +3241,16 @@ end_io: */ void generic_make_request(struct bio *bio) { + request_queue_t *q; + + BUG_ON(!bio->bi_bdev) + + q = bdev_get_queue(bio->bi_bdev); + if (q && q->bio_limit != -1U) { + wait_event_interruptible(q->wait, q->bio_queued + 1 <= q->bio_limit); + q->bio_queued++; + } + if (current->bio_tail) { /* make_request is active */ *(current->bio_tail) = bio; diff --git a/fs/bio.c b/fs/bio.c index 093345f..0a33958 100644 --- a/fs/bio.c +++ b/fs/bio.c @@ -1028,6 +1028,16 @@ void bio_endio(struct bio *bio, unsigned int bytes_done, int error) bio->bi_size -= bytes_done; bio->bi_sector += (bytes_done >> 9); + if (!bio->bi_size && bio->bi_bdev) { + request_queue_t *q; + + q = bdev_get_queue(bio->bi_bdev); + if (q) { + q->bio_queued--; + wake_up(&q->wait); + } + } + if (bio->bi_end_io) bio->bi_end_io(bio, bytes_done, error); } diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index db5b00a..7ce0cd7 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -467,6 +467,9 @@ struct request_queue struct request *orig_bar_rq; unsigned int bi_size; + wait_queue_head_t wait; + unsigned int bio_limit, bio_queued; + struct mutex sysfs_lock; }; @@ -764,6 +767,30 @@ extern long nr_blockdev_pages(void); int blk_get_queue(request_queue_t *); request_queue_t *blk_alloc_queue(gfp_t); request_queue_t *blk_alloc_queue_node(gfp_t, int); + +static inline void blk_queue_set_limit(request_queue_t *q, unsigned int limit) +{ + q->bio_limit = limit; +} + +static inline void blk_set_bdev(struct bio *bio, struct block_device *bdev) +{ + request_queue_t *q; + + if (!bio->bi_bdev) { + bio->bi_bdev = bdev; + return; + } + + q = bdev_get_queue(bio->bi_bdev); + if (q) { + q->bio_queued--; + wake_up(&q->wait); + } + + bio->bi_bdev = bdev; +} + extern void blk_put_queue(request_queue_t *); /* -- Evgeniy Polyakov - 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/