linux-kernel - Re: [PATCH] ufs: core: add caps UFSHCD_CAP_MCQ

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Message-ID: <d78b244b-e032-4d6f-b6bf-87be2a98693d@acm.org>
Date: Mon, 21 Apr 2025 23:57:23 -0700
From: Bart Van Assche <bvanassche@....org>
To: Huan Tang <tanghuan@...o.com>, peter.wang@...iatek.com
Cc: James.Bottomley@...senPartnership.com, alim.akhtar@...sung.com,
 avri.altman@....com, ebiggers@...gle.com, linux-kernel@...r.kernel.org,
 linux-scsi@...r.kernel.org, manivannan.sadhasivam@...aro.org,
 martin.petersen@...cle.com, minwoo.im@...sung.com,
 opensource.kernel@...o.com, quic_nguyenb@...cinc.com
Subject: Re: [PATCH] ufs: core: add caps UFSHCD_CAP_MCQ_EN


On 4/21/25 11:25 PM, Huan Tang wrote:
> I found that using low-end UFS in SoCs that support MCQ may cause
> device latency to reach extreme values.

Hi Huan,

What is the root-cause of the high latency? If it is the time spent in
UFS interrupt handlers, please try to switch to threaded interrupt
handlers instead of disabling MCQ. See also
https://lore.kernel.org/linux-scsi/20250407-topic-ufs-use-threaded-irq-v3-0-08bee980f71e@linaro.org/

Bart.