From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757245AbXD0VDF (ORCPT ); Fri, 27 Apr 2007 17:03:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757276AbXD0VDE (ORCPT ); Fri, 27 Apr 2007 17:03:04 -0400 Received: from gretel.pobox.com ([208.58.1.197]:60627 "EHLO gretel.pobox.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757245AbXD0VDB (ORCPT ); Fri, 27 Apr 2007 17:03:01 -0400 X-Greylist: delayed 1889 seconds by postgrey-1.27 at vger.kernel.org; Fri, 27 Apr 2007 17:03:01 EDT Message-ID: <46325A6F.4050705@pobox.com> Date: Fri, 27 Apr 2007 16:17:51 -0400 From: "Alan D. Brunelle" Reply-To: Alan.Brunelle@pobox.com User-Agent: Thunderbird 1.5.0.10 (X11/20070403) MIME-Version: 1.0 To: linux-kernel@vger.kernel.org Cc: Jens Axboe Subject: [PATCH linux-2.6-block.git] Fix blktrace trace ordering for plug branch Content-Type: multipart/mixed; boundary="------------020605070204010906010503" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This is a multi-part message in MIME format. --------------020605070204010906010503 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit The attached patch will correct the ordering of trace output between request queue insertions (I) and unplug calls (U). Right now the insert precedes the unplug, which just isn't right: 65,128 0 1 67.699868965 7882 Q R 0 + 1 [aiod] 65,128 0 2 67.699876462 7882 G R 0 + 1 [aiod] 65,128 0 3 67.699878286 7882 P W [aiod] 65,128 0 4 67.699880491 7882 I R 0 + 1 [aiod] 65,128 0 5 67.699887589 7882 U R [aiod] 1 65,128 0 6 67.699898317 54 D R 0 + 1 [kblockd/0] 65,128 2 153 67.700126590 0 C R 0 + 1 [0] With the patch provided the unplug comes first: 65,128 3 1 0.000000000 7045 Q R 0 + 1 [aiod] 65,128 3 2 0.000002295 7045 G R 0 + 1 [aiod] 65,128 3 3 0.000002617 7045 P W [aiod] 65,128 3 4 0.000003685 7045 U R [aiod] 1 65,128 3 5 0.000004107 7045 I R 0 + 1 [aiod] 65,128 3 6 0.000009491 57 D R 0 + 1 [kblockd/3] 65,128 2 1 0.000232447 0 C R 0 + 1 [0] Jens: If you agree, the patch can be applied to your plug branch for git://git.kernel.dk/data/git/linux-2.6-block.git Thanks, Alan --------------020605070204010906010503 Content-Type: text/x-patch; name="fix-unplug-order.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="fix-unplug-order.patch" From: Alan D. Brunelle Fix unplug/insert trace inversion problem. Signed-off-by: Alan D. Brunelle --- block/ll_rw_blk.c | 8 ++++---- include/linux/blkdev.h | 1 + 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c index 46d29f7..3bec97f 100644 --- a/block/ll_rw_blk.c +++ b/block/ll_rw_blk.c @@ -2981,6 +2981,7 @@ out_unlock: if (bio_data_dir(bio) == WRITE && ioc->qrcu_idx == -1) ioc->qrcu_idx = qrcu_read_lock(&q->qrcu); list_add_tail(&req->queuelist, &ioc->plugged_list); + ioc->plugged_list_len++; } out: @@ -3720,7 +3721,6 @@ void blk_unplug_current(void) struct io_context *ioc = current->io_context; struct request *req; request_queue_t *q; - int nr_unplug; if (!ioc) return; @@ -3735,19 +3735,19 @@ void blk_unplug_current(void) if (list_empty(&ioc->plugged_list)) goto out; - nr_unplug = 0; + blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL, ioc->plugged_list_len); + spin_lock_irq(q->queue_lock); do { req = list_entry_rq(ioc->plugged_list.next); list_del_init(&req->queuelist); add_request(q, req); - nr_unplug++; } while (!list_empty(&ioc->plugged_list)); + ioc->plugged_list_len = 0; spin_unlock_irq(q->queue_lock); queue_delayed_work(kblockd_workqueue, &q->delay_work, 0); - blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL, nr_unplug); out: /* diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index f8cdd44..848564c 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -113,6 +113,7 @@ struct io_context { */ int plugged; int qrcu_idx; + int plugged_list_len; struct list_head plugged_list; struct request_queue *plugged_queue; --------------020605070204010906010503--