Re: [PATCH] ufs: core: Improve IOPS

["Peter Wang (王信友)" <peter.wang@mediatek.com>]

On Wed, 2025-08-13 at 10:10 -0700, Bart Van Assche wrote:
> Measurements have shown that IOPS improve by 2% - 3% on my UFS 4 test
> setup every time a ktime_get() call is removed from the UFS driver
> command processing path. Hence this patch that modifies
> ufshcd_clk_scaling_start_busy() such that ktime_get() is only called
> if the returned value will be used.
> 
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---
>  drivers/ufs/core/ufshcd.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index b20f262fc8e4..9579e2481062 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -2231,11 +2231,13 @@ 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();
> +       ktime_t curr_t;
> 
>         if (!ufshcd_is_clkscaling_supported(hba))
>                 return;
> 
> +       curr_t = ktime_get();
> +
>         guard(spinlock_irqsave)(&hba->clk_scaling.lock);
> 
>         if (!hba->clk_scaling.active_reqs++)

Hi Bart,

Although this may not cause any errors, it is clearly a 
coding defect that impacts performance.
Have you considered adding a "Fixes" and "Cc" tag to 
address this issue?

Thanks.
Peter