From patchwork Thu Jun 11 10:10:43 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stanley Chu X-Patchwork-Id: 11599683 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 CD44014B7 for ; Thu, 11 Jun 2020 10:10:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B085820801 for ; Thu, 11 Jun 2020 10:10:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mediatek.com header.i=@mediatek.com header.b="A1BCONdo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727023AbgFKKKx (ORCPT ); Thu, 11 Jun 2020 06:10:53 -0400 Received: from mailgw01.mediatek.com ([210.61.82.183]:39543 "EHLO mailgw01.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726864AbgFKKKx (ORCPT ); Thu, 11 Jun 2020 06:10:53 -0400 X-UUID: 11bf0e1ac7714195b6b7c71141af5c4a-20200611 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Transfer-Encoding:Content-Type:MIME-Version:Message-ID:Date:Subject:CC:To:From; bh=x7vUWQFpnR/ub7QdtwzOjPmOJYfIbVlXp6l4yBKYLHw=; b=A1BCONdoKjTbjvHdJerYczh7j+rXqtvTg8MmZCQBg56NrqMNX1n5k0zxv+p402jied5+fdkwJhTvYJwo6tuj2loRuXS0kdM2yUxXmRFdFsmhKRP8p0CSLpZikVD14uBqDrXjzBW+AKtQrrYgBJPAlhw9qVNWeywCRggFSY95kmQ=; X-UUID: 11bf0e1ac7714195b6b7c71141af5c4a-20200611 Received: from mtkcas06.mediatek.inc [(172.21.101.30)] by mailgw01.mediatek.com (envelope-from ) (Cellopoint E-mail Firewall v4.1.10 Build 0809 with TLS) with ESMTP id 1225472788; Thu, 11 Jun 2020 18:10:50 +0800 Received: from mtkcas07.mediatek.inc (172.21.101.84) by mtkmbs08n2.mediatek.inc (172.21.101.56) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 11 Jun 2020 18:10:42 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas07.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Thu, 11 Jun 2020 18:10:42 +0800 From: Stanley Chu To: , , , , , CC: , , , , , , , , , , , , , Stanley Chu Subject: [PATCH v5] scsi: ufs: Fix imprecise load calculation in devfreq window Date: Thu, 11 Jun 2020 18:10:43 +0800 Message-ID: <20200611101043.6379-1-stanley.chu@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-TM-SNTS-SMTP: 63D7B33707924DB214DD98270AC3D06C1753746E0E6DE21450E38B69674B86C92000:8 X-MTK: N Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.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 | 18 ++++++++++-------- drivers/scsi/ufs/ufshcd.h | 2 +- 2 files changed, 11 insertions(+), 9 deletions(-) diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index ad4fc829cbb2..7a344658325d 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->busy_start_t)); + scaling->tot_busy_t += ktime_us_delta(curr_t, + scaling->busy_start_t); - stat->total_time = jiffies_to_usecs((long)jiffies - - (long)scaling->window_start_t); + stat->total_time = ktime_us_delta(curr_t, scaling->window_start_t); stat->busy_time = scaling->tot_busy_t; start_window: - scaling->window_start_t = jiffies; + scaling->window_start_t = 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 = 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; } } diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h index bf97d616e597..16187be98a94 100644 --- a/drivers/scsi/ufs/ufshcd.h +++ b/drivers/scsi/ufs/ufshcd.h @@ -411,7 +411,7 @@ struct ufs_saved_pwr_info { struct ufs_clk_scaling { int active_reqs; unsigned long tot_busy_t; - unsigned long window_start_t; + ktime_t window_start_t; ktime_t busy_start_t; struct device_attribute enable_attr; struct ufs_saved_pwr_info saved_pwr_info;