linux-kernel - Re: [PATCH v5] scsi: ufs: Fix imprecise load calculation in devfreq window

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Message-Id: <159227986423.24883.5364281872549678357.b4-ty@oracle.com>
Date:   Mon, 15 Jun 2020 23:59:59 -0400
From:   "Martin K. Petersen" <martin.petersen@...cle.com>
To:     linux-scsi@...r.kernel.org, jejb@...ux.ibm.com,
        avri.altman@....com, Stanley Chu <stanley.chu@...iatek.com>,
        asutoshd@...eaurora.org, alim.akhtar@...sung.com
Cc:     "Martin K . Petersen" <martin.petersen@...cle.com>,
        peter.wang@...iatek.com, beanhuo@...ron.com,
        matthias.bgg@...il.com, bvanassche@....org,
        linux-kernel@...r.kernel.org, andy.teng@...iatek.com,
        cc.chou@...iatek.com, cang@...eaurora.org,
        linux-arm-kernel@...ts.infradead.org, kuohong.wang@...iatek.com,
        chaotian.jing@...iatek.com, chun-hung.wu@...iatek.com,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH v5] scsi: ufs: Fix imprecise load calculation in devfreq window

On Thu, 11 Jun 2020 18:10:43 +0800, Stanley Chu wrote:

> 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.
> 
> [...]

Applied to 5.9/scsi-queue, thanks!

[1/1] scsi: ufs: Fix imprecise load calculation in devfreq window
      https://git.kernel.org/mkp/scsi/c/b1bf66d1d5a8

-- 
Martin K. Petersen	Oracle Linux Engineering