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Wed, 10 Jun 2020 21:29:23 -0800 Received: from MTKMBS02N2.mediatek.inc (172.21.101.101) by MTKMBS62N1.mediatek.inc (172.29.193.41) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 10 Jun 2020 22:21:11 -0700 Received: from MTKCAS06.mediatek.inc (172.21.101.30) by mtkmbs02n2.mediatek.inc (172.21.101.101) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 11 Jun 2020 13:21:11 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by MTKCAS06.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Thu, 11 Jun 2020 13:21:09 +0800 From: Stanley Chu To: , , , , , Subject: [PATCH v4] scsi: ufs: Fix imprecise load calculation in devfreq window Date: Thu, 11 Jun 2020 13:21:09 +0800 Message-ID: <20200611052109.22700-1-stanley.chu@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-TM-SNTS-SMTP: 15808926AE20E5473D36ADD8ADA4232D6CE1F132A283B18C20BE289C9826830A2000:8 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200610_222935_053533_089ACEA9 X-CRM114-Status: GOOD ( 10.72 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.4 on bombadil.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 0.0 MIME_BASE64_TEXT RAW: Message text disguised using base64 encoding 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.0 UNPARSEABLE_RELAY Informational: message has unparseable relay lines X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: bvanassche@acm.org, andy.teng@mediatek.com, cc.chou@mediatek.com, chun-hung.wu@mediatek.com, kuohong.wang@mediatek.com, linux-kernel@vger.kernel.org, cang@codeaurora.org, linux-mediatek@lists.infradead.org, peter.wang@mediatek.com, matthias.bgg@gmail.com, Stanley Chu , chaotian.jing@mediatek.com, linux-arm-kernel@lists.infradead.org, beanhuo@micron.com Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org The UFS load calculation is based on "total_time" and "busy_time" in a devfreq window. However, the source of time is different for both parameters: "busy_time" is assigned from "jiffies" thus has different accuracy from "total_time" which is assigned from ktime_get(). Besides, the time of window boundary is not exactly the same as the starting busy time in this window if UFS is actually busy in the beginning of the window. A similar accuracy error may also happen for the end of busy time in current window. To guarantee the precision of load calculation, we need to 1. Align time accuracy of both devfreq_dev_status.total_time and devfreq_dev_status.busy_time. For example, use "ktime_get()" directly. 2. Align below timelines, - The beginning time of devfreq windows - The beginning of busy time in a new window - The end of busy time in the current window Fixes: a3cd5ec55f6c ("scsi: ufs: add load based scaling of UFS gear") Signed-off-by: Stanley Chu Reviewed-by: Avri Altman --- drivers/scsi/ufs/ufshcd.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index ad4fc829cbb2..bf5aaf334ccd 100644 --- a/drivers/scsi/ufs/ufshcd.c +++ b/drivers/scsi/ufs/ufshcd.c @@ -1314,6 +1314,7 @@ static int ufshcd_devfreq_get_dev_status(struct device *dev, unsigned long flags; struct list_head *clk_list = &hba->clk_list_head; struct ufs_clk_info *clki; + ktime_t curr_t; if (!ufshcd_is_clkscaling_supported(hba)) return -EINVAL; @@ -1321,6 +1322,7 @@ static int ufshcd_devfreq_get_dev_status(struct device *dev, memset(stat, 0, sizeof(*stat)); spin_lock_irqsave(hba->host->host_lock, flags); + curr_t = ktime_get(); if (!scaling->window_start_t) goto start_window; @@ -1332,18 +1334,17 @@ static int ufshcd_devfreq_get_dev_status(struct device *dev, */ stat->current_frequency = clki->curr_freq; if (scaling->is_busy_started) - scaling->tot_busy_t += ktime_to_us(ktime_sub(ktime_get(), + scaling->tot_busy_t += ktime_to_us(ktime_sub(curr_t, scaling->busy_start_t)); - stat->total_time = jiffies_to_usecs((long)jiffies - - (long)scaling->window_start_t); + stat->total_time = ktime_to_us(curr_t) - scaling->window_start_t; stat->busy_time = scaling->tot_busy_t; start_window: - scaling->window_start_t = jiffies; + scaling->window_start_t = ktime_to_us(curr_t); scaling->tot_busy_t = 0; if (hba->outstanding_reqs) { - scaling->busy_start_t = ktime_get(); + scaling->busy_start_t = curr_t; scaling->is_busy_started = true; } else { scaling->busy_start_t = 0; @@ -1877,6 +1878,7 @@ static void ufshcd_exit_clk_gating(struct ufs_hba *hba) static void ufshcd_clk_scaling_start_busy(struct ufs_hba *hba) { bool queue_resume_work = false; + ktime_t curr_t = ktime_get(); if (!ufshcd_is_clkscaling_supported(hba)) return; @@ -1892,13 +1894,13 @@ static void ufshcd_clk_scaling_start_busy(struct ufs_hba *hba) &hba->clk_scaling.resume_work); if (!hba->clk_scaling.window_start_t) { - hba->clk_scaling.window_start_t = jiffies; + hba->clk_scaling.window_start_t = ktime_to_us(curr_t); hba->clk_scaling.tot_busy_t = 0; hba->clk_scaling.is_busy_started = false; } if (!hba->clk_scaling.is_busy_started) { - hba->clk_scaling.busy_start_t = ktime_get(); + hba->clk_scaling.busy_start_t = curr_t; hba->clk_scaling.is_busy_started = true; } }