From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 02454C11F66 for ; Tue, 29 Jun 2021 13:41:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DB50D61DC8 for ; Tue, 29 Jun 2021 13:41:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233957AbhF2Nnn (ORCPT ); Tue, 29 Jun 2021 09:43:43 -0400 Received: from so254-9.mailgun.net ([198.61.254.9]:56506 "EHLO so254-9.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233605AbhF2Nnm (ORCPT ); Tue, 29 Jun 2021 09:43:42 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1624974075; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=530miHsQki4P/yb0X7Er46fBJDy8EGHKDfjCTh5c3A8=; b=n2QEwibvOIHzpVaYRzVt/wvB58HTGl+9tUeBP1Ph2oPGtBRytCzddnMjVeZHLNLooYZzxzE8 Ekb0k4X213fjQd2ze8qluuJbwBkR1RTy3JgmW+2PUr9+dIyiVbGJ/LDRnWo3M89papfUcT39 pwwt3T5ojwdh06v207n4rUC6oXE= X-Mailgun-Sending-Ip: 198.61.254.9 X-Mailgun-Sid: WyJlNmU5NiIsICJsaW51eC1zY3NpQHZnZXIua2VybmVsLm9yZyIsICJiZTllNGEiXQ== Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n02.prod.us-east-1.postgun.com with SMTP id 60db22e77b2963a2821d03ee (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Tue, 29 Jun 2021 13:40:55 GMT Sender: cang=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 9A508C43148; Tue, 29 Jun 2021 13:40:54 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: cang) by smtp.codeaurora.org (Postfix) with ESMTPSA id D9972C433D3; Tue, 29 Jun 2021 13:40:50 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Tue, 29 Jun 2021 21:40:50 +0800 From: Can Guo To: Bart Van Assche Cc: "Martin K . Petersen" , "James E . J . Bottomley" , Jaegeuk Kim , Bean Huo , Avri Altman , Asutosh Das , Vignesh Raghavendra , linux-scsi@vger.kernel.org, Alim Akhtar , Stanley Chu , Adrian Hunter Subject: Re: [PATCH] ufs: Increase the usable queue depth In-Reply-To: <20210513164912.5683-1-bvanassche@acm.org> References: <20210513164912.5683-1-bvanassche@acm.org> Message-ID: <76395c748b265b7e05bc07094260ed18@codeaurora.org> X-Sender: cang@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Hi Bart, On 2021-05-14 00:49, Bart Van Assche wrote: > With the current implementation of the UFS driver active_queues is 1 > instead of 0 if all UFS request queues are idle. That causes > hctx_may_queue() to divide the queue depth by 2 when queueing a request > and hence reduces the usable queue depth. > > The shared tag set code in the block layer keeps track of the number of > active request queues. blk_mq_tag_busy() is called before a request is > queued onto a hwq and blk_mq_tag_idle() is called some time after the > hwq > became idle. blk_mq_tag_idle() is called from inside > blk_mq_timeout_work(). > Hence, blk_mq_tag_idle() is only called if a timer is associated with > each > request that is submitted to a request queue that shares a tag set with > another request queue. Hence this patch that adds a > blk_mq_start_request() > call in ufshcd_exec_dev_cmd(). This patch doubles the queue depth on my > test setup from 16 to 32. > > In addition to increasing the usable queue depth, also fix the > documentation of the 'timeout' parameter in the header above > ufshcd_exec_dev_cmd(). > > Cc: Can Guo > Cc: Alim Akhtar > Cc: Avri Altman > Cc: Stanley Chu > Cc: Bean Huo > Cc: Adrian Hunter > Fixes: 7252a3603015 ("scsi: ufs: Avoid busy-waiting by eliminating tag > conflicts") > Signed-off-by: Bart Van Assche > --- > drivers/scsi/ufs/ufshcd.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c > index c96e36aab989..e669243354da 100644 > --- a/drivers/scsi/ufs/ufshcd.c > +++ b/drivers/scsi/ufs/ufshcd.c > @@ -2838,7 +2838,7 @@ static int ufshcd_wait_for_dev_cmd(struct ufs_hba > *hba, > * ufshcd_exec_dev_cmd - API for sending device management requests > * @hba: UFS hba > * @cmd_type: specifies the type (NOP, Query...) > - * @timeout: time in seconds > + * @timeout: timeout in milliseconds > * > * NOTE: Since there is only one available tag for device management > commands, > * it is expected you hold the hba->dev_cmd.lock mutex. > @@ -2868,6 +2868,9 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba > *hba, > } > tag = req->tag; > WARN_ON_ONCE(!ufshcd_valid_tag(hba, tag)); > + /* Set the timeout such that the SCSI error handler is not activated. > */ > + req->timeout = msecs_to_jiffies(2 * timeout); > + blk_mq_start_request(req); > > init_completion(&wait); > lrbp = &hba->lrb[tag]; We found a regression after this change gets merged - schedule blk_mq_get_tag __blk_mq_alloc_request blk_get_request ufshcd_exec_dev_cmd ufshcd_query_flag ufshcd_wb_ctrl ufshcd_devfreq_scale ufshcd_devfreq_target devfreq_set_target update_devfreq devfreq_monitor process_one_work worker_thread kthread ret_from_fork Since ufshcd_devfreq_scale() blocks scsi requests, when ufshcd_wb_ctrl() runs, if it cannot get a free tag (all tags are taken by normal requests), then ufshcd_devfreq_scale() gets stuck, thus scsi layer stays blocked, which leads to I/O hung. Maybe consider unblocking scsi requests before call ufshcd_wb_ctrl()? Thanks, Can Guo.