linux-kernel - Re: [PATCH V2] scsi: ufs: ufs-qcom: Update UFS devfreq Parameters

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Message-ID: <20230720082602.GA4863@thinkpad>
Date:   Thu, 20 Jul 2023 13:56:02 +0530
From:   Manivannan Sadhasivam <mani@...nel.org>
To:     Nitin Rawat <quic_nitirawa@...cinc.com>
Cc:     quic_cang@...cinc.com, stanley.chu@...iatek.com,
        bvanassche@....org, quic_asutoshd@...cinc.com, avri.altman@....com,
        martin.petersen@...cle.com, beanhuo@...ron.com,
        konrad.dybcio@...aro.org, linux-scsi@...r.kernel.org,
        linux-kernel@...r.kernel.org, agross@...nel.org,
        andersson@...nel.org, jejb@...ux.ibm.com,
        linux-arm-msm@...r.kernel.org, quic_ziqichen@...cinc.com
Subject: Re: [PATCH V2] scsi: ufs: ufs-qcom: Update UFS devfreq Parameters

On Sun, Jul 16, 2023 at 01:19:07PM +0530, Nitin Rawat wrote:
> To support the periodic polling mode without stop caused by CPU idle
> state, enable delayed timer as default instead of deferrable timer
> for qualcomm platforms.

How about,

"Devfreq uses the default DEVFREQ_TIMER_DEFERRABLE mode which uses the deferred
timer for scheduling the devfreq load monitor function. This causes the load
monitoring to be done only with non-idle CPUs and not making use of the idle
CPUs. Hence, use the DEVFREQ_TIMER_DELAYED mode which uses the delayed timer
thereby making use of idle CPUs as well for load monitoring."

> And change UFS devfreq downdifferential threshold to 65 for less
> aggressive downscaling.
> 

This change needs to be done in a separate patch. Also please provide any
benchmark if available to justify the patch.

> Signed-off-by: Nitin Rawat <quic_nitirawa@...cinc.com>
> Signed-off-by: Asutosh Das <quic_asutoshd@...cinc.com>

Your signed-off-by should come last, as you are the one sending this patch.

- Mani

> ---
> 
> Changes in v2:
> - Realigned the commit text
> 
>  drivers/ufs/host/ufs-qcom.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
> index 82d02e7f3b4f..a15815c951ca 100644
> --- a/drivers/ufs/host/ufs-qcom.c
> +++ b/drivers/ufs/host/ufs-qcom.c
> @@ -1388,8 +1388,9 @@ static void ufs_qcom_config_scaling_param(struct ufs_hba *hba,
>  					struct devfreq_simple_ondemand_data *d)
>  {
>  	p->polling_ms = 60;
> +	p->timer = DEVFREQ_TIMER_DELAYED;
>  	d->upthreshold = 70;
> -	d->downdifferential = 5;
> +	d->downdifferential = 65;
>  }
>  #else
>  static void ufs_qcom_config_scaling_param(struct ufs_hba *hba,
> --
> 2.17.1
> 

-- 
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