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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-BeenThere: linux-mediatek@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 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.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 --- 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; } } -- 2.18.0 _______________________________________________ Linux-mediatek mailing list Linux-mediatek@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-mediatek