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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 5A348C433ED for ; Tue, 6 Apr 2021 05:43:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E68B613B3 for ; Tue, 6 Apr 2021 05:43:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231861AbhDFFnu (ORCPT ); Tue, 6 Apr 2021 01:43:50 -0400 Received: from so254-9.mailgun.net ([198.61.254.9]:14849 "EHLO so254-9.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231710AbhDFFnu (ORCPT ); Tue, 6 Apr 2021 01:43:50 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1617687823; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=8fMoin8EECddFTnxPjCHC3sjKD+IeeTDtKRJyMFadhg=; b=Bq93JfoHcWjUmi5Rk/pwcHxqOSOCzMfteucyJJTWfmLiP1iMF5f/O3FLY1SPKKuUh6CnwsTd 1G5klvWml47fYgCclQah3/KM9aZsxk/74BlUAXnYE4/dArIKFzUBI/RIJ0LJeITpo1JUML3S WoADC8r8JCRhNjDg1Fc2KbYORkw= 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-n05.prod.us-east-1.postgun.com with SMTP id 606bf5068166b7eff74a3c35 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Tue, 06 Apr 2021 05:43:34 GMT Sender: cang=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 4A58FC43466; Tue, 6 Apr 2021 05:43:33 +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 35E35C433CA; Tue, 6 Apr 2021 05:43:32 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Tue, 06 Apr 2021 13:43:32 +0800 From: Can Guo To: daejun7.park@samsung.com Cc: asutoshd@codeaurora.org, nguyenb@codeaurora.org, hongwus@codeaurora.org, linux-scsi@vger.kernel.org, kernel-team@android.com, ALIM AKHTAR , Avri Altman , "James E.J. Bottomley" , "Martin K. Petersen" , Stanley Chu , Bean Huo , Jaegeuk Kim , Adrian Hunter , Kiwoong Kim , Satya Tangirala , open list Subject: Re: [PATCH 1/2] scsi: ufs: Introduce hba performance monitor sysfs nodes In-Reply-To: References: <1617257704-1154-2-git-send-email-cang@codeaurora.org> <1617257704-1154-1-git-send-email-cang@codeaurora.org> <1891546521.01617683881598.JavaMail.epsvc@epcpadp4> Message-ID: X-Sender: cang@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 2021-04-06 13:37, Can Guo wrote: > Hi Daejun, > > On 2021-04-06 12:11, Daejun Park wrote: >> Hi Can Guo, >> >>> +static ssize_t monitor_enable_store(struct device *dev, >>> + struct device_attribute *attr, >>> + const char *buf, size_t count) >>> +{ >>> + struct ufs_hba *hba = dev_get_drvdata(dev); >>> + unsigned long value, flags; >>> + >>> + if (kstrtoul(buf, 0, &value)) >>> + return -EINVAL; >>> + >>> + value = !!value; >>> + spin_lock_irqsave(hba->host->host_lock, flags); >>> + if (value == hba->monitor.enabled) >>> + goto out_unlock; >>> + >>> + if (!value) { >>> + memset(&hba->monitor, 0, sizeof(hba->monitor)); >>> + } else { >>> + hba->monitor.enabled = true; >>> + hba->monitor.enabled_ts = ktime_get(); >> >> How about setting lat_max to and lat_min to KTIME_MAX and 0? > > lat_min is already 0. What is the benefit of setting lat_max to > KTIME_MAX? > >> I think lat_sum should be 0 at this point. > > lat_sum is already 0 at this point, what is the problem? > >> >>> + } >>> + >>> +out_unlock: >>> + spin_unlock_irqrestore(hba->host->host_lock, flags); >>> + return count; >>> +} >> >> >>> +static void ufshcd_update_monitor(struct ufs_hba *hba, struct >>> ufshcd_lrb *lrbp) >>> +{ >>> + int dir = ufshcd_monitor_opcode2dir(*lrbp->cmd->cmnd); >>> + >>> + if (dir >= 0 && hba->monitor.nr_queued[dir] > 0) { >>> + struct request *req = lrbp->cmd->request; >>> + struct ufs_hba_monitor *m = &hba->monitor; >>> + ktime_t now, inc, lat; >>> + >>> + now = ktime_get(); >> >> How about using lrbp->compl_time_stamp instead of getting new value? > > I am expecting "now" keeps increasing and use it to update > m->busy_start_s, > but if I use lrbp->compl_time_stamp to do that, below line ktime_sub() > may > give me an unexpected value as lrbp->compl_time_stamp may be smaller > than > m->busy_start_ts, because the actual requests are not completed by the > device > in the exact same ordering as the bits set in hba->outstanding_tasks, > but driver > is completing them from bit 0 to bit 31 in ascending order. Sorry, I missunderstood your point... Yes, we can use lrbp->compl_time_stamp. Thanks, Can Guo. > >> >>> + inc = ktime_sub(now, m->busy_start_ts[dir]); >>> + m->total_busy[dir] = ktime_add(m->total_busy[dir], >>> inc); >>> + m->nr_sec_rw[dir] += blk_rq_sectors(req); >>> + >>> + /* Update latencies */ >>> + m->nr_req[dir]++; >>> + lat = ktime_sub(now, lrbp->issue_time_stamp); >>> + m->lat_sum[dir] += lat; >>> + if (m->lat_max[dir] < lat || !m->lat_max[dir]) >>> + m->lat_max[dir] = lat; >>> + if (m->lat_min[dir] > lat || !m->lat_min[dir]) >>> + m->lat_min[dir] = lat; >> >> This if statement can be shorted, by setting lat_max / lat_min as >> default value. > > I don't quite get it, can you show me the code sample? > > Thanks, > Can Guo > >> >>> + >>> + m->nr_queued[dir]--; >>> + /* Push forward the busy start of monitor */ >>> + m->busy_start_ts[dir] = now; >>> + } >>> +} >> >> Thanks, >> Daejun