b1bf66d1d5
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(). In addition, 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 the following 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 Link: https://lore.kernel.org/r/20200611101043.6379-1-stanley.chu@mediatek.com Fixes: a3cd5ec55f6c ("scsi: ufs: add load based scaling of UFS gear") Reviewed-by: Avri Altman <avri.altman@wdc.com> Signed-off-by: Stanley Chu <stanley.chu@mediatek.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.