From patchwork Wed Sep 2 20:19:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gabriel Krisman Bertazi X-Patchwork-Id: 11751721 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 56E8C161F for ; Wed, 2 Sep 2020 20:19:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3D46420BED for ; Wed, 2 Sep 2020 20:19:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726269AbgIBUTe (ORCPT ); Wed, 2 Sep 2020 16:19:34 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:44418 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726226AbgIBUTe (ORCPT ); Wed, 2 Sep 2020 16:19:34 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: krisman) with ESMTPSA id 1239429A1D3 From: Gabriel Krisman Bertazi To: Jens Axboe Cc: Ming Lei , linux-block , kernel@collabora.com Subject: [PATCH v2] block: Consider only dispatched requests for inflight statistic Organization: Collabora References: <20200831153127.3561733-1-krisman@collabora.com> <87wo1dpclt.fsf@collabora.com> Date: Wed, 02 Sep 2020 16:19:28 -0400 In-Reply-To: (Jens Axboe's message of "Tue, 1 Sep 2020 16:39:09 -0600") Message-ID: <87r1rkorsf.fsf_-_@collabora.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Jens Axboe writes: > We just need to decide if this makes sense or not. I think we should > apply this for 5.10, with Ming's suggestion of using > blk_mq_request_started(). Then I guess we'll see what happens... Hello, Here is the second version, then. But, instead of blk_mq_request_started as suggested on the review, this uses blk_mq_rq_state to access the state attribute, since we don't want to include MQ_RQ_COMPLETE. Also, improved the commit message a bit. Thanks, >8 According to Documentation/block/stat.rst, inflight should not include I/O requests that are in the queue but not yet dispatched to the device, but blk-mq identifies as inflight any request that has a tag allocated, which, for queues without elevator, happens at request allocation time and before it is queued in the ctx (default case in blk_mq_submit_bio). In addition, current behavior is different for queues with elevator from queues without it, since for the former the driver tag is allocated at dispatch time. A more precise approach would be to only consider requests with state MQ_RQ_IN_FLIGHT. This effectively reverts commit 6131837b1de6 ("blk-mq: count allocated but not started requests in iostats inflight") to consolidate blk-mq behavior with itself (elevator case) and with original documentation, but it differs from the behavior used by the legacy path. Signed-off-by: Gabriel Krisman Bertazi --- Changes Since v1: - Use blk_mq_rq_state to fetch req->state - Improve commit message block/blk-mq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 0015a1892153..bee55f80fb69 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -105,7 +105,7 @@ static bool blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx, { struct mq_inflight *mi = priv; - if (rq->part == mi->part) + if (rq->part == mi->part && blk_mq_rq_state(rq) == MQ_RQ_IN_FLIGHT) mi->inflight[rq_data_dir(rq)]++; return true;